The Secret Diary of Doug Lord

My work here is done

2011-02-04T22:28:00.001-08:00

As the real Doug is now blogging ... adieu.

http://forums.sailinganarchy.com/index.php?app=blog&module=display&section=blog&blogid=36

High Performance Monofoilers-altitude control

2010-12-01T03:28:00.001-08:00

One very interesting development over the last year (and sure to be repeated on other boats) is manually controlled altitude that by-passes the wand on the 26' Mirabaud. The guys on the boat say it is particularly useful in choppy water where the wand can create a real bumpy ride.

I've foiled my own 16' boat using a manual control system* and despite some problems I feel it is a great way to foil and I think it has great potential in racing foilers. Here is a post from last year quoting TomSpeer on manual control of the mainfoil flap:

" If you look at the conditions for stable flight, the forward foil must have a relatively higher heave stiffness than the rear foil, and the rear foil must cause a greater change in pitching moment with a change in angle of attack than the forward foil. This is why wand feedback to the forward foil and a fully submerged aft foil work so well together. The heave stiffness of the aft foil is virtually zero, so it does all the job of stabilizing the craft in pitch. The forward foil then is totally responsible for controlling the craft in heave.

Manual control of altitude via the forward flap makes sense, since that is the surface that really controls heave. But the big difficulty is having enough control power to handle both the dynamic change in lift needed by the control system, and being able to trim out the change in lift due to speed. With direct gearing between the wand and flap and the boat flying at a constant pitch attitude, the only way for the control system to trim out the increase in speed with lift is to deflect the flap upward, and because of the gearing between flap and wand, this means flying higher.

If the boat is trimmed bow down as the speed changes, then the reduced angle of attack will compensate for the speed and the boat can fly at its design height with the foil centered (on average). One way to get this pitch trim is with manual control of the stern flap. The speed changes less rapidly than flying through waves or even being hit by gusts. So pitch trim with speed makes sense for manual control.

It might be possible to get some automatic speed trim by clever manipulation of the hinge moments on the rudder flap. Aircraft use a device called a "down spring" to augment their speed stability. A spring with a low spring constant is used to apply a near constant nose down force to the controls. This has to be trimmed out with the trim tab. But the force from the trim tab depends on speed. So as the speed increases, the tab effectiveness increases and moves the elevator in the nose-up direction. This makes the aircraft climb, which reduces the speed.

The opposite could be applied to a hydrofoil. If the rudder flap were deflected upward with a spring, increasing speed would reduce the deflection. This would make the boat trim more bow down, reducing the flying height in much the same way as the manual pitch trim described above. You could also divide the rudder flap into two parts - one driven by the spring and the other under manual control.

Naturally, the spring force would control the amount of automatic trim change. It's better to get the force from deflecting a long, weak spring a lot, than by deflecting a short, stiff spring. This makes a bungee cord ideal for the purpose. " Tom Speer

(* also have used a manual system on two different rc boats with great success )

18' Tri vs F18 Cat : potentially the full potential

2010-11-18T05:05:00.001-08:00

I think an area worth exploring is what the potential is for an 18' tri-as well as how much of that potential is required to whip an F18.
This is an example of what the full potential of an 18' tri is, potentially

MAX RM:

1) F18-- crew CG at 11' from lee hull CB( 320 X 11= 3520ft.lb.) + boat CG at approx. 3.8' from lee hull CB with windward hull just flying( 396 X 3.8= 1504 ft.lb.)
TOTAL RM = 5024 ft.lb.

2) 18' square tri(18 X 18)-- crew CG at 21' from lee hull CB( 21 X 320=6720 ft. lb.) + boat CG at approx. 8.75' from lee hull CB with main hull just flying(396 X 8.75= 3465 ft. lb.)
TOTAL RM = 10185 ft. lb.
====================

So the max RM from a square tri with the same weight crew as an F 18 is
2.02 times that of an F18(or more). It is probably possible to build a square 18'tri at the same weight as an F18-the Gougeons built a C Class tri(25') with an 18' beam that weighed 300 lb. in 1969.
My personal opinion is that this MAX RM tri is not necessary to beat an F18. A tri with less max RM would still be more powerfull than an F 18 yet allow the crew to sit in a much more comfortable position. For the tri to work in light air as well as heavy air it is absolutely critical to use two lifting foils on the main hull: in light air they allow the boat to fly the main hull in 5 knots of wind. In every condition they add tremendous pitch control to a very powered up boat.
=======================
The use of foils is becoming more and more apparent on monohulls and multihulls alike. Foils are tools that can modify characterisics of a boat such that what might be untenable with a foiless design becomes possible with foils. Like an 11' monohull that beats all beach cats under 20'!
A boat does not have to be fully airborn to be using foils successfully-"foil assist" is probably one of the most overlooked applications of foils.
Foils can add stability where only weight worked in the past, they can drastically modify the pitch characteristics of any boat. They can improve handling in rough conditions. They can contol the angle of heel of a trimaran(or catamaran)-and more.
They can't just be tacked onto a design-they have to be carefully implemented.
The absurd sentiment that "because it hasn't been done before it can't be done now" is nonsense.
Carefull, modern, innovative design can make a high performance "beach tri" a reality that will be faster on the water and more comfortable to sail shorthanded or with a crew at a cost comparable to top end cats.
I've put forth some ideas that I think could be part of such a design but by no means are my ideas the last word on the subject.

More Comfort- More Speed- Wide crew range(singlehanded or doublehanded with MAX power)
==================
See Martin Fischer interview about the use of foils in multihull design: http://catsailingnew...in-fischer.html

---------------------

I'll post some specs comparing the "low powered" daysailing version of the 18 tri with an F18. What is very critical to realize is that on either the high powered version or the daysailer the boat will(must) fly the main hull in as little as 5 knots of wind-that is absolutely critical to the success of either version. The boat is simply too wide with too much RM(esp. the daysailer version) to do that without the foils on the main hull. After the mainhull lifts off and speed increases the foils will UNLOAD until ,at some point, the ama takes the full load(either a planing ama or ama+ foil).
The wand is set to control the heeling angle of the boat like it controls altitude on a normal full blown foiler like a Moth. There is a side benefit to using the foils for early liftoff of the main hull and pitch control: because the wand is set for a specific altitude(heeling angle) if the boat begins to exceed that angle even by a little the wand will cause the main foil to pull down. This can be used to sail the fully powered up

daysailer version singlehanded in the same maximum pressure it can be sailed doublehanded.

Trapwing model opps I mean prototype

2010-05-17T02:11:00.001-07:00

This is a unique design that uses ballast in a sealed wing in several different versions.

Yes, there are numbers and yes there are pictures of a model of the prototype, cause that's how I roll.

Here are some details:

-----------

Trapwing Prototype: LOA 17' 8"(5.38m) Beam hull-3.25'(1 m) overall 12'(3.66m)(subject to testing) Weight- hull 155lb ballast-wing 80lb(36.3kg)-180lb(81.8kg)(variable and subject to testing) keel 0-80lb(36.3kg)(subject to testing)dinghy version-no keel. SA-upwind 100sq.ft(9.3sq.m)-180sq.ft(16.7 sq.m) variable downwind 200sq.ft(18.6sq.m)-360sq.ft(33.46sq.m). (variable and subject to testing) crew-singlehanded-120lb(54.5kg)-220lb(100kg) (variable and equalized under class rules- subject to testing) crew position for racing on the centerline inside boat, fixed athwhartships, variable fore and aft

--------------------

1) Sail area to be between 100sq.ft(9.3sq.m) and 180 sq.ft(16.7 sq.m) a-different rigs b-different amounts of ballast

2) Ballast wing to be supported by trapeze wires and unique retention system that allows wing and ballast to slide simultaneously, allows athwhartship pivoting and fore and aft movement. a-version one will use two aluminum tubes with sliding external tray- the tubes and tray move simulataneously: -attachment system allows wing- with weight centered-to be levered up and then pivoted from a position 90 degrees to the CL to a position parallel to the centerline for transport and stowage. -weight can be added or removed in small increments. -fore and aft pivot/sliding tube is mounted to the boat slightly offset from the CL to allow room to retract board/keel. -aluminum tubes terminate at outboard ends in buoyancy pods-pods will be changeable as determined in testing. -sliding ballast tray and structural design of wing to be capable of 180lb(81.8kg) max ballast @9'(2.5m) from CL; ballast completely adjustable in the range of 80(36.3kg) to 180lb(81.8kg).

b-version two is a slightly curved(athwhartship), molded and sealed(with sealable access to ballast tray) wing with an internal sliding ballast tray. This version will be the final version and incorporates all the features of version one with significantly increased sealed buoyancy. c-Wing movement by manual or electric means. Minimum electrical movement speed 4' per second. Minimum electrical "stamina" on single battery-12 hours at a rate equivalent to a approximately 60 (full track)tacks per hour. Now I know that this is illegal based on current US Sailing rules, but rules are for wimps.

------

3) Crew Position a-version one-racing position-allows crew to sit in an extremely comfortable seat that is fixed athwhartship and slides fore and aft adjustably while sailing. -extremely wide crew weight range:for racing lower tray attached to seat may contain ballast used to equalize crew weight in the range of 120lb.(54.5kg) to 220lb.(100kg) -seat may be moved manually or electrically. b-version two-center seat is removed and two fixed carbon seats with backrests are "plugged-in" to each side deck.

-- 4) Rigs to be tested are main and jib, main alone, jib alone, with and without an asymetrical spinnaker and no sails at all. a-asymetrical will be tested as permanently mounted off a bowsprit(a la Weta tri) or retracted into a trough with roller(a la Viper) and a retractable pole (a la the local strip club). b-mast to be sealed with masthead floatation in an endplate configuration. Some buoyancy possible in head of sail.

-- 5)-Daggerboard/ keel/rudder a -boat will be tested with and without a retractable "lifting keel" which would essentially be a carbon daggerboard with the minimum ballast required(determined in testing) to right the boat from a pitchpole(where the wing buoyancy may not significantly help). b-self-righting from a knockdown or pitchpole is a required design element for any version of the boat used for disabled sailing.

c-a turbo version of the boat will not use a ballasted keel and may not be suitable for disabled sailing but this will be determined in testing. d- the daggerboard may include as standard a lifting hydrofoil designed to provide "foil-assist" to reduce wetted surface and in conjunction with the rudder hydrofoil improve the pitch and planing characterstics of the boat. e-a fully flying hydrofoil system will be tested as will a fully flying system that allows the boat to fly downwind only(requiring less upwind SA and less ballast). f-rudder will be retractable with a t-foil, and a j-foil or is it a k-bulb, or an f-boat I forget, no wait it's a c-cat.

6)-On the Beach a-the boat will be able to be easily beach sailed with a dolly incorporated into the trailer design to make it very simple to go from trailer to water. A "power assist" dolly may be available, this 20' crane can also be used to park your car if required.

7)-Performance a- the goal is to develop a high performance planing sailboat that can be safely sailed from a center crew position by disabled or able-bodied sailors. I am hoping to be able to achieve an SCP/total weight of 30% or slightly better though that is just a target and a less powerfull version with numbers and performance more like a Windmill or Tasar, or Optimist may be perfectly acceptable. The use of foil-assist technology will help to achieve the performance goals, or make the boat as slow as molasses, Full flying foiling is possible in a selfrighting boat-particularly one with the righting assist this boat has from version two of THE Wing. This wing was licensed to Larry for his little trimaran that he sailed off the coast of spain.

The concept has extraordinary potential and it will be a blast finding out just what she'll do. Now I just need to find the remote control.

Veal Heel for Multihull Foilers

2009-11-08T13:28:00.001-08:00

One of the most recent major contributions to the physics of sailing has come from the little Moth monofoiler: it is called "veal heel" after Rohan Veal who developed it.

Nothing new about heeling a boat to windward except when that boat is flying on hydrofoils. In that case with the boat heeled to weather the Righting Moment(RM) is increased by the amount the boat and crew CG move to weather of the center of lift of the foils.

Not only that but the struts(daggerboard and rudder) supporting the hydrofoils are unloaded and a component of the hydrofoil lift acts to weather improving upwind vmg.

Multifoilers,to date, have either sailed level or heeled like a "normal" sailboat.( except for an unsuccessful experiment in the C class)
I think there may be a better way on a high performance trimaran that would use very small "amas" like the Rave but with a major difference: the new boat would use two foils-like a Moth- for boat speeds up to say, 20 knots. After that the boat would deploy(retractable) very small foils from the vicinity of the windward ama that would generate downforce to increase RM.

I did a rough comparison of two boats each weighing exactly what a Rave does and the wetted surface is less at least up to 30 knots boat speed but whats more drag is less again, at least up to 30 knots. This thing could be designed to be MUCH lighter than a Rave(368lb) and could be substantially faster in 5-20 knots of wind.

But what is really cool is that the new concept foiler would sail with "veal heel" with the attendant advantages upwind.

Comments welcome.....

60' Moth-A Preliminary Detailed Design Exploration

2009-10-22T23:42:00.000-07:00

60' Moth-A Preliminary Detailed Design Exploration

Please read the whole thing if you're interested. I consulted with a naval architect on this and tried to be as detailed a possible. Questions and comments from those interested are encouraged.

==================================
60' MOTH-A Preliminary Detailed Design Exploration
==================================

I've long been convinced that the bi-foil revolution in dinghy design sparked by the Moth Foiler has potential for larger boats as well. The Out 95 guys in the UK and Sean Langman are also exploring this idea-among others. I decided to look at the numbers for a scaled up Moth just for the hell of it. I was surprised by the results.

---------------------
I) The base boat: LOA- 12.75', SA- 86 sq.ft.;weight: 60lb.hull + 150 lb. crew =210lb.s all up.
II) Scaling up:
*A) Sail Area-Since sail area varies as the square of length I squared 12.75(162.5) and squared 60(3600). Then I divided 3600 by 162.5 and multiplied the result by 86(Moth SA) . So the scaled up SA=1905sq.ft.----------------------- ****
Weight- Weight/displacement varies as the cube of the length. So I cubed 12.75 (2072.67) and cubed 60(216000).Then I divided 216000 by 2072.67 and multiplied the result by 210(Moth sailing weight). So the weight of the scaled up boat is 21,884 lb.'s.----------
III) Analysis/judgement calls- The most surprising thing when I was first doodling with these figures is the weight. At almost 22,000 pounds the scaled up Moth was way heavy by comparison to an ORMA 60 trimaran(12,000lb.'s) and to L'hydroptere(11,975lb.'s). But the defining characteristic of the Moth above all else is that it is a MONOHULL. So to preserve that characteristic at this length I decided that it would be important that the boat was selfrighting like any other(hopefully) 60'monohull. The "weight budget" certainly would allow that.
==================================
NOTE:VERY IMPORTANT: the resulting 60'monofoiler IS NOT, REPEAT NOT a scaled up Moth as a carefull reading of this Design Exploration will reveal.
This Design Exploration reveals that while this self-righting 60' monohull foiler is possible and has speed potential AT LEAST equal to the ORMA foil assist trimarans it is nonetheless on the leadingedge of what is possible today.

=================================
So this is what I came up with after playing with the numbers for some time and running the whole thing by a friend who is a naval architect:
60' MONOFOILER-----------------------------
1)LOA-60'-------------------------------------
2) Target Beam 50'-increase from scaled up Moth; about same proportion as aeroSKIFF 14(see post#15 Peoples Foiler Thread)
3)Target SA: 2500 sq.ft.-increase from scaled up
Moth.------------------------------
4)Target Minimum all up sailing weight including 5231 lb.s on an 18' 60° canting strut: 14,731lb.'s.--------------------------------
5) Target boat weight w/o canting keel ballast:
9500lb.'s--------------------
6) Maximum additional ballast: 3771 lb.'s water ballast in a sliding tank-perhaps sliding within forward cross beam or just aft of beam. Tank is filled while over hull to limit weight of plumbing requirements. approx. dimensions: 1.5' X 6' X 6.4'. Possible fore and aft ballast sliding system .----------------------------------------
7) Weight with maximum ballast:18502lb.'s(plus 2-4 crew)
==================================
Summary:
-LOA*60'---------------------------------------
-Beam-50'--------------------------------------
-SA 2500sq.ft.----------------------------------- -Displacement:
14,731lb.'s ; Max: 18502---
-Draft(off foils) max
18'-------------------------
30 sq.ft. main foil; 15 sq.ft rudder
foil-------*
===============================================
COMPARISONS--------------------------------
----------------------------------------------
D/L ratio- 60' Monofoiler: 30.4--------------- D/L ratio- Orma 60/L'hydroptere: 24.8------
Bruce Number-60' Monofoiler: 2.03---------
Bruce Number-ORMA Tri: 2.39--------------
Bruce Number-L'hydroptere:2.65------------
(Bruce number is the sq.rt .of SA divided by the cube root of displacement)----------- --------- For what it's worth, the following comparison is between the 60'Monofoiler and the 60'ORMA trimaran.And I consider it one of the most important comparisons of all. The ORMA trimaran is presumed to have 60% of it's displacement supported by a "banana foil", with 30% of it's weight supported by the ama while flying the main hull. For this comparison the 60'Monofoiler is presumed to be flying on just two foils. The vertical fins of neither boat are included and both sides of the foils are included:
1)Orma 60-estimated ama wetted surface 124 sq.ft; estimated foil wetted surface 32 sq.ft.(both sides) Total 156 sq.ft. Now this figure is divided into SA(3000sq.ft.) giving 19 sq.ft. of SA per sq.ft.of wetted surface.
2) 60'Monofoiler Mainfoil area(both sides): 60sq.ft..Rudder foil area(both sides) 30sq.ft.. Total is 90 sq.ft . Dividing SA(2500sq.ft.) by this figure gives 27.7 sq.ft. of SA per sq.ft. of wetted surface.
==================================
**Notes and Design Considerations
( see below for "More notes..." including lift calculations, foil
loading and more)
==================================
A) The number one design consideration for this boat was that it was self righting and that it would qualify as a monohull under any rule. Therefore it does not have buoyancy pods that in any way resemble or that could function like a hull-simple rectangular spaces at the maximum beam supported by carbon cross tubes. These buoyancy tanks in combination with the 18' 5000+lb. 60° canting bulb would prevent capsize and or right the boat from a knockdown. The weight in the bulb was specifically chosen to be 1.5 times what would be required to right the boat from a pitchpole. The canting keel could be explored a lot since it is relatively light for a 60 footer(5200+lb.'s). It would be ideal for it to be clear of the water when the boat is foiling-at least above 20 knots.
When an Orma tri fly's the main hull it does so with about 2lb. per sq.ft. of windpressure on 3000 sq.ft. of sail. The 60'Monofoiler with max ballast can sail with it's maximum SA in about the same pressure. And in lighter conditions it can ditch up to 3700+ lb.'s of water ballast facilitating relatively light air take off in an 9-12 knot wind.------------------------------
(see Righting Moment below)
==================================
Preliminary conclusions:
It appears to me that the 60' monofoiler could be built but right at the top end of available technology.It would be likely to equal a multi of it's own size that did not use foils and appears to have more SA per sq.ft. of wetted surface than even an ORMA tri though especially in light air the ORMA would be faster since it can retract it's hydrofoil . The concept of an extremely fast selfrighting hydrofoil holds a lot of promise.
===================================
--------------------------------
More notes and references:
1) Righting Moment---------------------------
When off the foils the heeling arm (CE-CLR) is 43'. When on foils it is 51.75' . Hull bottom clearance to water is 10.75'. On foils max draft ,level,is 5'.
This boat is a monofoiler and as such will be sailed heeled to weather 15° at maximum righting moment.
Elements of Righting Moment:
A) rig CG is approximately at the
CE; 1460lb. @ 14.5' to weather= 21,170ft.lb.
B)canting bulb- 5,231lb.'s at 60°( 15.6') +
3' weather heel =5231 X 18.6'= 97,296 ft. lb.'s.
C)Hull 8040 X 5'to weather= 40,200ft.lb.
D)rack(deck) ballast 23' = 6' to weather
=29 X 3771= 109,359 ft. pounds
================================================
MAXIMUM RIGHTING MOMENT= 268,025 ft. lb.'s (A+B+C+D above)
MAXIMUM PRESSURE WITH 2500sq.ft.(268,025 divided by 51.75=5179. Divide 5179 by 2500(SA) = 2.07 lb.
================================================
2) The 50' beam could be one "wing" but would probably work better as two beams supporting a fixed empty "tank" at each end for buoyancy. A small tank containing up to 3770 pounds of water will also slide across the forward beam or just behind it. For the sake of getting the boat defined as a monohull based on whatever rule the buoyancy would not look like or function like a hull while normally sailing. In the event of a knockdown it would help to right the boat. I've talked with Alex of the OUT 95 project and he says their solution(ultra narrow hull with very wide wings on a 32 footer) is legal under the rules. Exactly which rules he was referring to I'm not exacly sure.
********The hydrofoils on this 60' monofoiler are in the hull : one mounted on the daggerboard and one mounted on the rudder.They might be partially retractable in non foiling conditions. No foils on the end of the wings.The canting keel strut would be behind the daggerboard.(Like Maximus among others)
----------------------------------------------
3) The canting strut is right on the edge of feasibility. But it probably can work: its half the weight of a VO 70 bulb but half again as long.Based on the fact that the load is 81% of the load on a Vo70 the engine hp required is likely to be about 23hp(vs 29 for the Volvo).
The Volvo 70 has a max speed so far of 40.6 knots according to Sail mag-just 5 knots short of the top end(so far) of a G Class cat(100+')-same source. And ,as I understand it, they peg the keel max out in fast conditions.
The Farr design #550 Volvo 70 has a strut approximately 12-13' long with 9920 pounds in the bulb with a variable displacement from 27,558 to 30,865lb.'s. The monofoiler as stated above needs 5200+lb.'s at 18' to be self rightng.
******I don't think that the bulb/strut being offset will have too much negative effect when you consider that L'hydroptere maintains control at over 40 knots with most of the drag coming from a foil 20' to leeward using a centerline rudder. I think that it would be important on the monofoiler to figure out a way to get the canting strut and bulb out of the water over 20 knots-keeping in mind that it will probably be sailed upwind with windward heel like the Moth. The Volvo has a max cant angle of 40°, the Schock 40 and Max Z86's 55° and a 26 footer from Bethwaite 60°.
**This area would need plenty of research and testing. It is ripe for some sort of unique solution....
----------------------------------------------
4) Bruce numbers- I calculated the Bruce number for L'hydroptere from information on Sail Area given in Sail mag.. But looking at the head-on picture and using a scale ruler I'll bet they can't carry that area(3700sq.ft.) in the same pressure that an Orma tri can carry it's 3000sq. ft. The monofoiler can carry it's maximum sail area in the same pressure an Orma tri can carry it's maximum sail area. Regardless of it's actual SA for a given pressure a well designed multifoiler will be faster than the 60 monofoiler any day. But the monofoiler and ORMA even using "foil assist" will be closer.And a "conventional" multi sailing only on it's hulls(even flying the main hull with no foil assist) would be still closer in speed to the monofoiler-with the monofoiler probably having a significant edge.
**I 'm leaning toward believing that the Bruce Number or Bethwaites "SCP Divided By Total Weight Ratio" may not be good comparitive numbers when comparing an all out foiler to a "foil assist" boat like the Orma. **When you look at these Bruce Numbers you may see what I mean: Moth 1.56 ; A Class Cat 1.82 ; 49er 1.76 ; IC 1.58 . All the boats shown show a Bruce number indicating they should be faster than a Moth-and they are when it is not foiling. But when on foils the Moth beats every one of these boats. So I'm leaning toward SA/wetted surface as a possible way to compare the boats when at least one of them is a foiler. In my comparison of the 60' monofoiler to the ORMA I showed that even though the foiler was heavier it had more power applied to less wetted area than did the ORMA. Of course ,this is simplistic: it didn't take into account induced drag of the foils, the vertical fins or the wavemakng resistance of the partially submerged ORMA ama. Nonetheless, it seems like a good indicator....
----------------------------------------------
5) Foil Loading- The 60' monofoiler will have foil loadings with and with out the sliding deck ballast. For takefoff(see #5 for lift/speed calculations) it has a foil loading of 392.8 pounds per sq.ft . That is based on 80% of the total dispacement of 14731 which equals 11784 divided by 30 sq.ft.. Above 20 knots ,at some point, it will add additional ballast and have a foil loading of 493 pounds at a displacement of 18502lb.. Most foilers are designed with about 80%(or so) of the load on the forward foil and loading is calculated based on the area of one side.
****For comparision the foil loading of the ORMA tri with and estimated banana foil area of 16sq.ft. is 450lb. per sq.ft. at a displacement of .6 X 12000=7200. A Rave foiler sailing in 2lb. of pressure has a mainfoil(2) loading of 356lb. per sq. ft. (develops RM using the foils increasing loading well past this number at max pressure). A Moth has a mainfoil loading of 169 lb.per sq.ft.-and only changes with different crew weight. And the first two person monofoiler to fly-David Lugg's I14 had an approx. mainfoil loading of over 500 pounds per sq.ft. (small "high speed" foils), if I remember correctly.
L'hydroptere has surface piercing foils and basically starts out with low loading and high wetted surface(56 sq.ft.est.) and ends up with high loading and low wetted surface(14 sq.ft.est.). The picture of L'hydroptere in Sail shows it sailing on one of two main foils at an area I estimate to be 7 sq.ft. for a loading of 1368lb per sq.ft.(.8 X 11975 divided by 7). I'm guestimating that that picture was taken when the boat momentarily flew a foil and that a more realistic loading would be based on 14 sq.ft.(7sq. ft. per main foil) for a realistic loading of 684 lb.'s per sq.ft. At takeoff with 56 sq. ft. of foil area loading is 171lb.sq. ft. but the loading rapidly increases whereas it does not change on a monofoiler unless ballast is added.
----------------------------------------------
----------------------------------------------
Additional Notes: Using this formula for lift: Area=Weight divided by(the factor 2.09 X speed in mph² X Cl(coeficient of lift) along with my copy of Theory of Wing Sections and the information there on the 63412 section(p522 &523) I came up with the following for the monofoiler:
Light displacement =14731 .8=11784------
Heavy Displacement=18502 X .8=
14802--
Mainfoil area 30 sq.ft.--------------------------
==================================
1) The boat will lift off at a boat speed of 12 mph(10.4 knots) with a CL of 1.3. This is outside the drag bucket(but way below stall) but ,of course ,as soon as the boat lifts off it will accelerate.Moths, using this foil, lift off at even higher CL's.--------------------------------
2) At a boat speed of 16mph(13.9 knots) the CL drops to .73-just inside the "drag bucket" for this foil.-----------------------------
3)At 23 mph(20 knots) after the additional ballast is added the CL is .44-well within the drag bucket. The additional ballast may not all be added at once but I checked it at the minimum speed for which some ballast would be added.
==========================
A personal note: I'm not at all convinced that sailing foilers are a good idea for ocean racing until the electronic systems are developed to spot partially submerged objects in time to avoid them. L'hydroptere was stopped by just this kind of thing. I think all high performance boats would benefit from this kind of equipment and I imagine it's not too far away or may be already available for all I know. In fact according to the L'Hydroptere site they are experimenting with this kind of technology...

three boats in one

2009-10-20T10:30:00.000-07:00

I've started my second monohull foiler platform that will actually be three boats in one. The idea is to have a basic platform with interchangeable parts that will allow a 22' foiler, a 22' trimaran with planing amas and a 22' Trapwing experimental movable ballast boat.

All these variations use foils to one degree or another and the plan is to get the hardware built and be able to spend huge amounts of time sailing instead of building.

I should have a whole lot of fun and learn a lot over the next five years while I explore these ideas.

Thanks to my experience with Dr. Bradfield I've sailed a Rave a lot and coupled with the limited foiling on my own 16 footer I can tell you that foiling is one of the most thrilling things you can do on the water! Try it on any boat you can.

And keep in mind these are early days in the bi-foiler revolution-don't buy into the "its too hard" bull or that crap about having to walk a foiler out to deep water. The newer boats will be much more user friendly and yes,it is a revolution!

the latest design using a Blade F16 hull

2009-10-15T19:55:00.001-07:00

LOA 16' using a Blade F16 hull from Matt McDonald of Falcon,LLC in Port Canaveral, Fl.and:
Hull weight(with cockpit) 73lb(actual weight+ cockppit mod)
SA 160 sq. unstayed squaretop rig,carbon mast- 35lb
Foils-17lb (foil assist approx 70% lift depending on crew weight)
12' wing,all up-20lb
movable ballast-160 lb
motor,controls,battery (25lb est)

----------------------
SUB Total=330lb (405lb for Turbo self-righting version with fixed 75lb ballast in bulb integrated with "foil assist"foils)
crew=120-180lb
TOTAL = 510lb
====================
RM:
160@ 9' =1440ft.lb
20 @ 4' = 80ft.lb

------------------------------
Total= 1520ft.lb

HM@ 1lb/sq.ft. pressure = 1600 ft.lb.
------------------------------------

This is with crew contributing virtually nothing to RM. A side seat option allows the crew to sit slightly outboard but still in a relatively fixed position-for ablebodied crew only and it adds RM.
There is no guarantee that even after testing the skinny hull turbo version will be suitable for disabled sailors-only extensive testing will prove whether or not that is possible. IF that is possible it REQUIRES the selfrighting option.
==============

This thing will trailer with the wing pivoted fore and aft and will require the same room a WETA tri does to launch rigged at a launch ramp. In Florida the boat would launch using a dolly like a cat does and that will make it easy. Keep in mind how heavy the 2.4 meter is and it is successfully launched in many areas. This boat is much lighter than that-maybe about the same as a Bongo-and about the same as a Hobie 16. Launching will be no problem with a dolly on a beach and if the ramp is wide enough the boat can be launched right off the trailer.

The BOAT WILL NOT BE CARTOPABLE.

The lead in the cart that slides athwhartship will be in approx. 20lb segments an will be REMOVABLE. There is no reason to sail with max ballast on a light day.

A production version would have a reefable rig.

This version will not be the first version which will be my 22 footer which is being worked on now. It will be done as soon as possible.

Additions include front twin 50 cals so any one who claims I am not a sailing vessel can eat my lead

horsepetunias

2009-10-10T06:48:00.001-07:00

Heres a new rendering of my new favourite bi-foiler the KissKut.

Here are the numbers:

LOA 4.5 m=14.7'
Beam 4.5m=14.7'
SA=9sq.m=97 sq.ft
weight est.=40kg=88lb.
Price-an amazing(!) $42,000US no peoples foiler if this price is accurate.

I see some problems with veel heel-if anybody else does and can articulate it I'd sure like to know. Appears I have the wing angle slightly too low-that means max veel heel would be greater than this while maintaining the same clearance between buoyancy pod and water as between hull and water. I still don't like the twin vertical struts or the 7'(est) long main foil. A couple of things are immediately obvious: there is too much mainfoil area* and along with the twin struts that results in a drastic increase in wetted surface with veal heel when keeping the leeward tip the proper distance below the surface.

* estimated 3.5 sq. ft.; foil loading with 320lb crew=93lb/sq.ft. Moth foil loading=160lb.per sq.ft. approx. This foil could be shortened to approx. 4' with a 6" chord. and ha
ve the same foil loading as a Moth and that is with TWO people on board KissKut. That would help everything... but it would be even better when jumped with manual control and dual midship wands.

Some mothies think it won't work. To that I say horsepetunias

Questions and answers

2009-10-07T06:16:00.001-07:00

1) Do you think that a bi-foiler could be designed to be significantly easier to sail than a Moth?
Technically a moth is a sub category of bi-foiler, so, logically speaking, the question is do I think that a bi-foiler can be faster than a bi-foiler, ergo if we apply the atlernative, can a moth be designed to be faster than a bi-foiler. well no because it is one, so then the question becomes can a moth be faster than a moth, well yes a moth can be designed to be faster than a moth, however by definiton it is a moth, so it can't be. In summary, a bi-foiler cannot be designed to be faster than itself.

2) Do you think a forward wand position is critical or could a midship or aft wand could have some potential?
the forward positioning of the wand is absolutley critical. If the wand is not held tightly then an expelleramus spell will easliy disengage the wand from your hand. Storing the wand aft could solve this issue however it would impact the wand users ability to cast spells.

3) Do you see any potential value in a control system that links the movement of the mainfoil flap and rudder foil flap(or rudderfoil angle of incidence) together in an adjustable(mixable) way?
I think that any system that links the two foils together, say using some 2" x 1" tiber) into a single, unified foil would cause an excessive amount of drag as it is pulled through the water under the boat, so no. I like the idea of the mix tape though.

4) Do you think a bi-foiler could be faster if altitude was controlled manually(no wand)-even if it took lots of practice to get it right?
Well spell casting does take a lot of practice to get things right, and you can cast faster if your attitude is done manually.

5) Do you think in some future time the idea of intentionally jumping a bi-foiler(not necessarily a Moth) would be feasible-or catch on if it could be done safely, repeatedly?
Jumping is fiesable and necessary. When trying to escape persuit from the Hazzard county sherrif, jumping over the nearest river with a washed out bridge into the next county has shown to be able to be done every week for a number of years.

6) Do you think a keelboat, with the right numbers, could ever foil?
Didn't that Americas cup boat America II have a foil winged keely thing, so YES.

7) Where do you see bi-foiler development,outside the Moth Class, heading?
I think that bi-folding chairs were well developed before the moth class ever came along.

9) What is your opinion on a variable geometry main foil-a foil design where the area could be reduced under sail(or increased for that matter)?
I am sorry, I didn't pass geometry at school and will have to pass on this one.

10) What is your opinion of adding wand+flap altitude control to a surface piercing foilers main foils?
I don't have any surface piercings, as my mother won't let me get them, she says they will make me look cheap.

11) What do you think of adding buoyancy pods -a bit larger than the ones on current foilers- to help make it easier to learn to sail a monofoiler?
Why do we need bouyancy if the boat doesn't touch the water??

12) Did you know that several top Rave(16' multifoiler) sailors modified their boats to MANUAL altitude, MANUAL FOIL RM(roll) and MANUAL PITCH control which proved faster in racing-replacing the existing wand system?
I haven't been to a rave in years. At the last one I met a girl called Jenny who sold me a foil, she turned out to be a real mighty bitch, so I think that is what you mean, not manual pitch.

13) What is your opinion of adopting the "shared lift" concept first pioneered in the ARC 21 cat (and now with Mirabaud) to allow a longer foil "footprint" for a given size monofoiler?
Well I think it is a good idea that people use the shared lift concept. It reduces green house emissions as there are less cars on the road whihc reduces your footprint.

14) What effect do you think changing the planform and aspect ratio of the Rush foilboard(air chair derivitive) foils would have on speed, jumping, and "ease" of sailing a foilboard?
I think that changing the plan and form of the asphalt patio is a great idea. I don't think that rusing forward in to a chair delivery is a smart thingm less speed and reducing the urge to jump in will make things easier.

Groupthinkers

2009-06-11T06:48:00.000-07:00

I just want to welcome all my fellow Groupthinkers. There seems to be a misunderstanding. I think Sailing Anarchy should be a place where new ideas are discussed and where opinions out of the mainstream are tolerated and encouraged.

No way! Who ever came up with that lame ass idea doesn't know me. They will encourage you to say any thing you want BUT don't print any IDEAS that they don't understand, got it?

I talk about the first foiler in the US but don't have any pictures of it foiling. I must lying, right you brothers?

I bring up things nobody understands like some ratios and you know what?

They think I must be INSANE when I talk about "manual altitude control", "sportboat foiler", "a 60' Moth" or a powered up high fucking performance two person foiler!

AeroSKIFF

2009-06-06T17:42:00.000-07:00

This boat was designed by me at about the time the first Moth foiled(1999). It was built( mostly by me) over a three year period at a cost of around $17,000.And it was a blast to pull it all together. Among the things tried on this thing for the first time(as far as I know-at least in the US) were:
1) square top jibs (That's right it sailed with more than one at once)
2) reefable camber induced main. ( No one had used those two words before in the same sentence)
3) manual control of the main. ( 'cause everyone else uses a bow monkey)
4) angled up foil tips(lots of dihedral)-as a hunch to allow crash free jumping. ( or should that be snap free 'cause I don't want the foil to break)
5) angled up extension tiller ends to allow physical leverage for manual hydrofoil control (and man they look cool)
6) virtually no hull-just a scaled up skyrider, or a scaled up ironing board. I had two designs-one with a high beam to length ratio hull and buoyancy pods,one like this. My thinking at the time was to try to find a solution to the rollovers and difficulty common to the Moth at that time.They they fix by having half a clue about boat handling. I chose the wrong design-this hull was a bitch in the short chop of the intercoastal and actually delayed the takeoff that I was dreaming about in marginal conditions. Big mistake because ,for me, light air take off is the whole ball game. Assuming that there is a game, which I am not so sure about.
7) retractable foils controlled from the cockpit. The concept of a centreboard case was a real break through.
8) partial span mainfoil and rudder foil flaps( foils built to my design by John Ilett. Johns company engineered the foil laminated to be strong enough to jump the boat. In otherwords, they are solid carbon and weigh a ton.
9) tapered mainfoil planform
10) fully adjustable angle of incidence of both foils while sailing(main foil system disabled initially). I was in a hurry so sailed without this IMPORTANT system-and I would not have tried to foil if I had realized how much easier it was with this system active.
11) trailerable with foils retracted.
12) all carbon/foam
-----------------
The boat foiled rather poorly because of the hull design (no light air takeoff) but mainly because the mainfoil manual control system had slack in it making it very difficult to control. I consider the boat a success for many reasons including the fact that even though it was difficult to control it did foil 1 cm off the water and never once crashed. It taught me that there was a huge potential in further developing manual altitude control and adding a new feature to the new boat(under development now): simultaneous control of main and rudder foil.

The extension tiller with the turned up ends worked real well, the reefable main worked ok and the square top jibs have potential. The retractable foil system worked perfectly.

The first aeroSKIFF was a great learning experience and as far as I know the first monofoiler scratch built and designed in the US. It will not be the last....

JUMP RIGHT IN

2009-03-16T02:14:00.001-07:00

A boat designed to jump-particularly with a foil to cushion re-entry- is likely to be a lot of fun. Moths don't jump-intentionally- because they have wands. When a Moth gets high enough for the main foil to come out of the water the bungee pulls the wand all the way forward raising the back end of the flap resulting in a virtually instantaneous crash as the boat re-enters. This kind of crash happens often,particularly with bow mounted wands, in conditions where there are waves.

If I am correct in my assesment of the Howes foil the result of re-entry is likely to be more like the re-entry of a foilboard-and the jump done for the pure fun of it.

16-18' "Sit in" High Performance Dingh, - using on deck movable ballast

2009-02-19T02:20:00.001-08:00

I have always wanted to sail a boat like a 2.4 Meter but with much higher performance. I suggested a concept years ago and wonder if anyone else has any thoughts on how to make something like this work.

As I envision it the wing+ballast is supported by trapeze wires-side to side movement would not require a whole lot of effort....

Just as a rough illustration here is a picture of a Melges 24 model fitted with a "trapeze power ballast system". The battery was part of the sliding ballast and that could be done on a full size version.

The idea I had was to use a molded "wing" that would have ballast slide inside it to give large RM-similar to a two handed dinghy where one of the crew is on a trapeze. The ballast could be moved by hand, foot power or electrically. The boat might have a small fixed keel. The ends of the "wing" would be slightly larger in section to provide extra buoyancy. Each side of the wing would be supported by a "trapeze" wire making moving the whole wing(and the ballast inside it) fairly easy since it all moves horizontally.

The "wing" on the model is just two carbon tubes that form a track for the ballast to slide on. To me, a molded wing
on the fullsize version would have a number of advantages including lower aerodynamic drag, buoyancy and it could be built with a slight curve.

The idea is to sit in the boat like a 2.4 meter but plane early and fast.

photos of the first prototype

2009-02-10T00:59:00.001-08:00

You can't keep secrets for long. And before it hits the interweb, here it is ... the first production prototpe of the peoples foiler on its first test sail. With yours truly at the manual controls.

Just after this photo was taken, she got up and foiled for the first time, but the camera ran out of film.

This photo is on another test flight just prior to take off. At this point I was just about to engage the manual controls. It is a shame that the camera went flat just after this photo was taken.

On this photo you can clearly see the bouyancy pods working their magic and allowing a lot more power to be carried than a MOTH.

Bi-foiler with "Power Foils", idea that MIGHT add more "High" to Performance

2009-02-07T15:50:00.001-08:00

One of the great advantages of a boat like the Hobie trifoiler, Rave or Dr. Sams new Osprey is that that dual wands operate independently allowing the boat to develop all its own RM without input from the crew. Hydroptere and every surface piercer I know of develop RM differently by increasing the separation between the center of lift of the main foils and the boat CG as it heels(leeward foil develops an increasing amount of lift). Hydroptere uses movable ballast as well.

I've been toying with the idea of a hybrid: a "bi-foiler" that uses retractablesmall foils in each buoyancy pod-primarily in heavy air upwind. The point would be to increase the RM of the boat boosting upwind speed. The foil would be deployed in such a way as to hold the boat at a designed angle of veal heel along WITH crew participation. A target might be to add 50% to upwind RM and that would require a foil(actually one foil each side-only one used at a time) about half the size of a Moth mainfoil.

Disadvantages include the fact that two foils would be required and the additional weight. The gains could be appreciable, allowing a substantial increase in SA.

In light air the foils are retracted but the boat still has all the extra SA. So the gains would be not only upwind in heavy air but downwind in every condition and upwind and downwind in light air due to the extra power.

Takeoff would be significantly earlier than a "normal" bi-foiler....

Bradfield and Ketterman have already proved that the extra drag of a third foil is more than made up for in moderate to heavy air by the virtually unlimited rm available with their system. I think that it would be ideal to have these "power foils" able to be deployed without an altitude control system-a preset angle of incidence might work.

What do you think?

International 14's

2009-02-02T12:55:00.001-08:00

Most people probably know that the 14's are using a rudder foil that supports 25-30% of the sailing weight of the boat. What some people don't know is that the FIRST two person bi-foiler in the history of the world was an International 14 sailed in 1999 within months of John Iletts first sail of his foiling Moth.

Many people may not realize that this first foiling 14 also used MANUAL altitude control using a twist grip tiller operating the flap on the rudder foil.

Another first for David Lugg and Alan Smith who developed this boat.

turning on HUNDREDS of people

2008-12-28T14:51:00.001-08:00

I don't understand. I offered Bora the chance of a life time chance to make a real difference in building interest in the Moth -and foiling-while still getting your chance to try to ridicule me in front of HUNDREDS of people!!

I find it incredible that he would turn it down.

In early March(I think) Tinho Dornellas will have his annual Windsurfing Midwinters at his location here at Kelly Park on the Banana River. I suggested he come here then and put on a demonstration for the hundreds of people( many kids) and I'll sail the Moth when he's done.

When here he can go visit, Mickey Mouse(only 50 miles), and the space center as well as having the great pleasure of turning on HUNDREDS of people at one location. And make a great contribution to foiling in the US as well.

++++++++++++++++++++++++

Well Bora, are you in? You come down here and demonstrate the boat for the people and I'll still show you how to foil it!

Bethwaite foiling 49er

2008-12-26T04:47:00.000-08:00

The fact that Bethwaite is developing a BI-FOILER 49er is revealed in the Jan 2009 Seahorse with a picture, where you can clearly see the sliding bench seat.

Bethwaite is confident that his team is almost there, which is, of course a revolution.

====================

Shown underway as well is the notorius outboard powered 49er hull using three foils with a trailing edge wand on the forward foil.

Soon, when they learn the ways of foiling and grow in their knowledge of my patents, they too will want strike me down with all their hatred, and their journey towards the dark side will be complete.

the Master of Multifoiler Design is back!

2008-12-18T18:17:00.001-08:00

18' Multifoiler from Dr. Sam Bradfield, the Master of Multifoiler Design is back!

This time his boat has many new features including a new automatic altitude control system developed by the Hydrosail Team. Here are the specs:

Osprey
======

- 18’ racing trimaran
- highly-maneuverable, except when it is not
- light and lean for speed with large flight window
- T-foils with automatic flight control systems, that are manually controlled
- Park benches
- High windage Mirabaud style ~~pods~~ hulls
- Jump-o-matic version will be available

The two main foils roughly split the load-which is way more than the weight of the boat.

This is a new project with technology only hinted at in a few other foiler prototypes. Bradfield has held the world speed record in the B class with a foiler of his own design and comes second only to me when it comes to foiler development experience.

He is fully capable of producing an astonishingly high performance foiler.

I've always believed a bi-foil monofoiler was better than a Rave in light to moderate air-but this new boat(as I understand it) will be very light with no wands. Based on my numbers, it will take off in the same wind a Moth will.

And will have the same advantage the Rave did in winds over 20.

Bradfield is pioneering a differential altitude control system for the Osprey that will be extraordinary....

I am sure that this will be a great commercial success, just like the rave, and the Hobi trifoiler and the Kona kat.

Foiling crediblity

2008-12-11T17:56:00.001-08:00

I see an attitude lot from some Mothies: as far as foiling goes some of you think you're the only game in town.

That is no longer true since there are NON MOTH bi-foil monofoilers and multifoilers in development or being sailed all over the world. The attitude that you know all there is to know or will ever be known about foiling is bullshit-get over it!

My experience sailing 2 different monofoilers, 1 multifoiler is far more credible than a couple of years racing a moth.

====================

forget planing, the foiling sportsboat

2008-12-09T13:58:00.001-08:00

The next breakthru is not planing upwind-it is flying a sportboat upwind.....
30' LOA sportboat on foils:

My personal opinion is that chasing an upwind planing keelboat is a lot of effort to go a little faster-seems that a bi-foiler sportboat would be a better choice-a lot of effort to go a lot faster upwind and offwind.

BUT you should put some numbers on paper and see what it would take.
Bethwaites SCP/Total weight ratio predicts that a boat with a ratio over 30% will plane upwind. It goes like this:

RM(righting moment) divided by the distance between the CE(center of effort) and the CLP(CLR)(center of lateral pressure(resistance) equals SCP.

SCP divided by total weight is a percentage. It will work with metric or US measure-just use consistent units.

You can play with this to see what combination of SA,weight,RM will actually have a chance of working.

This also works(with other indicators) to predict "foilability" but was designed to predict upwind planing.

Another problem with planing monohull keelboats is the relatively wide hull that is generally thought to be requied. With a potential keelboat foiler you go with a 10/1 L/B ratio to start with(MAX width) so weight is already reduced a lot.

You can see below that its a bit tough to get good numbers.......

--------

Numbers for a foiler-for a planing hull weight would have to increase but there is enough margin for that, I think:

---LOA 24'
---LWL 24'
---Beam 18.6' (overall, incl. racks)2.4' at waterline
---Draft 6.5' keel,rudder retractable
---Sail Area 586sq.ft. upwind and downwind (planing boat would need big spin)
---Boat weight,incl. rig and ballast-1100lb.
---Ballast 490lb. (110° canting keel)110° canting keel wouldn't work on a planing hull so keel might have to be deeper @ 55-60° cant.
---Displacement (incl crew)-1420lb.
crew-320lb.
D/L=45.6
SA/D=74.3
SCP/Total weight=42%

===================

And before you say that it doesn't fit the rules. So what? Rules are meant to be changed when they hold back developement with artificial restrictions.

It's only a model

2008-12-09T13:49:00.001-08:00

The tips presented here will be those that I know work and that have been extensively tested on the water and in testing of two F3 hydrofoils side by side and Dr. Bradfields modified Flyer hydrofoil.

These foilers use fully submerged foils as opposed to surface piercing foils and the major advantage (in rc models) seems to be the fact that they generate their own stability. The more wind pressure ;the more stable the boat is.The F3 has been sailed in winds well over 20mph and the Flyer? in over 30.Fairly accurately ESTIMATED boat speed of the F3 in 16-22mph of wind=20mph.In 5-7mph of wind boat speed was ESTIMATED at 10-12 mph.

No other multihull available anywhere has this kind of automatic hands off stability system. On "normal" multihulls (F48,mini 40 and multiONE) immense concentration is needed just to keep the boat upright in medium to heavy air. The Bradfield type foiler ,like the F3, virtualy eliminates all those hassles and allows the skipper to just enjoy the speed without the capsize worry. A boat like this can still be capsized if it is set up incorrectly(set up should be a one time thing) or if too much sail is used for the conditions but I can supply a sail area guide that will eliminate that problem. And if you use the same rig as the F3, Flyer or X3 you won't need multiple rigs since those rigs reef thru out the windrange .

Another thing:the F3 type foiler can carry its "A"(unreefed) rig in higher winds than any other multihull because of the automatic stabitiy system but at some point sail will have to be reduced.I have a guide to knowing exactly when...

Foiling occurs on the F3 in 5-6mph of wind.Most of this is based on the F3; some ideas relating to the X3 retractable foiler are presented though that boat has not been tested yet.

Design Facts:

1) the quarter chord of the two main foils should be located so that they carry 80% of the weight and the rudder t-foil carries 20% of the weight. This generally results in a rig further forward than is "normal" on an rc multihull because the quarter chord of the vertical fin is, by necessity, in the same place. That is also the location of the CLR of the boat for balance(weather vs. lee helm)considerations.

2)A single cross arm is all that is necessary but it must be exceptionally stiff torsionally.

3) the center line of the outboard foils is ideally located about 1.07 times hull length apart centered on the main hull athwhartship. In the F48 class this is not possible and results in the hydrofoil for the f48 having to do slightly more work than that for the F3. In the multiONE Class while loa is one meter BOA is 48". The wider the boat the less the loading of the foils.In many tests the location of the vertical fins so far outboard has not affected tacking ability in the least; a foiler on foils will tack at least as fast as a fast monohull...

4) The automatic altitude control system depends on two"wands"which are straight or curved thin carbon tubes or rods that drag in the water. Before foiling the water pressure pushes them aft forcing the flap on the hydrofoil down to the high lift position. A spring or shock cord is attached to the wand so that as the boat rises the bottom of the wand moves forward neutralizing the flap on the foil or even creating negative lift.This is how the boat develops its own righting moment: the diferential lift required to create and maintain the exact right amount of lift AND righting moment is created by the movement of the wands connected to flaps on the two main forward hydrofoils: it is 100% automatic requiring no radio control!

5) The F3 will foil in very light air but because of the automatic altitude control system there is a lot of drag when not on foils.The "wands" can be removed in light air drmatically reducing drag since the flap is not then being automatically pushed into a high lift position. Or this type of foiler can be designed to use retractable foils which has not been tested in the water but since the foil system is identical and the rotation system so simple it should work but as yet this remains untested. F3 type foilers have been tested with no wands for light air.F3 One Design races would not be held in less than foiling conditions but F48,mini 40 & multiONE races will be held in very light conditions so it could pay if you consider an F48 size foiler to go ahead with a retractable system.

6) the main foils are installed as previously mentioned with a +2.5 degree angle of incidence relative to the flight waterline. The rear t-foil is set at 0 degrees.

Mainfoil area should be determined as follows:For a weight of 8 pounds the two main foils will lift 80% or 6.4lbs.; 3.2 pounds each. They require an area of 17 sq.inches to do that or .188lbs per square inch. Note that this is just to make calculation simple and does not reflect the ACTUAL loading of each foil since ,in developing righting moment, they are much more highly loaded. A Foiler should be designed with approximate 200 sq. in. of sail area per pound of weight. Of that sail area the MAIN foils should carry 49 sq.in. of sail area per sq.in of foil area.(Divide Sail Area by 49 to get mainfoil area=both foils; then divide in half for the area of one foil.Try to achieve the loading and sailarea for the foils and displacement of the boat.

In summary:

A).188lb.s per sq. inch loading of the main foils only -just using 80% of the boats weight.

B) 49 sq. in. of sail area per sq. in of main foil area. This can be varied a little and is applicable from a multiONE to a two meter.C) this will produce a boat that will take off in light air.(5-6mph)
The rudder t-foil should be 50% of the total of both mainfoils or slightly less.(Equivalent to one main foil works well)

7) The amas on a foiler the size of the F3(LOA 56") are 36" LOA with an 18/1 beam to length ratio and total buoyancy of 7 pounds. They are not capable of flying the main hull and do not need to be.Amas for an F48,mini 40 should be about the same size due to the proportionately narrower beam. For the multiONE they can be directly scaled down.

8)On the F3 the foils fit in trunks in each ama and that requires that not only the tube comprising the cross arm be exceptionally stiff torsionally but the joint between the ama and the cross arm needs to be exceptionally stiff. On the retractable design (untested as yet) the foils are mounted within carbon tubes that fit within bearings into another carbon tube allowing the whole foil/altitude control mechanism to rotate.Viewed from forward the foils rotate like airplane propellers toward the main hull untill they are vertical. The lower portion of each foil then acts as lateral resistance for the boat in light air.

The mounting of the rotational part of the the foil system allows the foil to have a zero degree angle of incidence when the foil is vertical. While I haven't tested this on the water yet I'm confident that it will work since it is so simple.The one downside may be the area of foil still in the water. The idea is to eliminate any need for a daggerboard when the foils are retracted by using the foils themselves as lateral resistance when they aren't being used for lift.

-----------------

You don't need a retractable system to enjoy sailing a foiler as described above; it takes off in such light air that you'll be foiling most of the time anyway. The only benefit to a retractable system is in light air or transitional foiling conditions(under 6mph wind) and the only benefit is in a class like the F48,mini 40 or multiONE in light air racing.

------
For anyone interested I can answer any questions and provide sketches of the wand system but the basics are here-you can design a foiler with the information provided above....

Oh, and it's only a model

High Performance Beach Cat Killer Tri Under 20', -capable of flying the main hull

2008-11-16T14:27:00.001-08:00

Why don't we see a tri like this anywhere? Seems like if the technology that has been applied to Orma Tri's, Banque Populaire,the DOG tri and Stealth beach cats was applied to,say, an 18 foot tri- cats would no longer rule 20' and under. Why isn't someone doing it-or are they?

What’s the point?
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More speed. You would have nearly twice the righting moment and 1.7 times the SA for any given length if you went all out. Should be faster in almost any condition than a cat of the same length.

Came up with this a couple of years ago and thought I'd mention the concept since I can't afford to patent it-and because I think it has a great deal of potential.

I was impressed by Yves Parlier's l'hydraplaneur which for those that don't know is an Open 60 multi with a difference: it is a cat with two stepped planing hulls looking somewhat like seaplane hulls.In the original article in Seahorse the boat was supposed to have some form of "variable geometry" to mitigate the negative effects of the steps at low speed. The article said the area of highest drag for the boat was between about eight knots and twenty knots with drag above twenty dropping to a fraction of the drag of a "normal" displacement multihull at that speed. In sailing against the ORMA tri's the boat showed flashes of speed but was basically crushed in the two races I'm familiar with.
Since I've designed and sailed numerous multihulls both full size and radio control the idea kind of interested me but I wanted a way to eliminate problems with the step at low and moderate speeds.What I came up with is this:

I envisioned a trimaran test boat 18' LOA with an 18' beam. The main hull would have a hydrofoil on the daggerboard and one on the rudder. But the amas are the key to this concept: they ROTATE! At slow-moderate speeds the ama is an 18-20/1 displacement hull but as the boat approaches a still to be determined "rotational" speed the windward ama is rotated 180°; the boat then tacks and the other ama is rotated .The bottom of the rotated ama is a stepped hull designed to reduce drag(up to 80% compared to a displacement high L/B hull) above a certain speed. The two foils are designed both to lift the mainhull early AND to possibly add to RM as max speed is approached.They also function to assure pitch stability given the massive sail carrying power of the boat.There is a lot of room for experimentation with the foils since it is possible that their area could be kept quite small. The test boat would be designed to utilize two crew trapezing off the windward ama.

I've built a small balsa model just to work out the geometry and it works out quite nicely.It is a weird looking hull with the displacement hull deck the bottom of the stepped planing hull! Next thing would be a fully functional rc model but that is quite a ways off. I think it is a beachcat killer with real high potential speed.Great applications on larger versions as well. But right now it's just an idea.... So what do you think?

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Rotation would be accomplished from the cockpit using a belt drive crank(wheel) with a separate actuator for a carbon pin. The boat would be engineered by a naval architect and a smaller test version would be built first. The foiler I am building now will have removable amas(to replace the pods) so that rotation can be experimented with fairly soon-6mos to a year from now, I hope). Not just rotation but also the variable angle of attack of the planing surface using two foils for pitch control.
I don't think a small trimaran has been done yet that incorporates the power this thing has-except maybe Exploder or Reynolds early tri. The boat is designed to fly the main hull(like an ORMA 60) from a boat speed of 5 knots and up with the foils used PRIMARILY for pitch control.
A few more notes:

1)The rotation is only done at the as yet to be determined crossover point-not necessarily when the main hull flys(which will be at about 5-6knots boat speed max.) but when the planing hulls will work optimally.

2) Rotation will be manual and very simple and quick-it would not be frequently done at most venues.

3) Shrouds ,if any, will go outboard almost max(or where the NA says). I would like to look very carefuly at an unstayed highspeed rig like a Moth type(w/o the stays) as well as a wing rig for a speed version depending on weight. My realistic guestimate is that a partially stayed rig will be required.

4) Estimated upwind SA for this boat is 380sq.ft. compared to 227 for the Hobie Tiger. The Max RM for the 18 tri would be 10512 ft.lb vs 5197 ft.lb for the tiger-over TWICE the Hobie RM for the 18.
This is based on two crew of 160lb. each on trapezes with the 18 just flying the main hull and the cat just flying the windward hull.

5) The 18 would have 2lb/sq.ft. sail loading vs 3.15 for the Tiger.

6) The Hobie weighs 397 lb. and is fiberglass/foam sandwich and this boat would be 100% carbon foam/honeycomb and a very rough estimate of weight would be all up at 447lb.

7)The boat could probably be "toned down" substantially and still beat most beach cats. The idea here is to illustrate what is possible with the trimaran configuration. One of the central themes of the 18 are the small hydrofoils on the daggerboard and rudder-FOR PITCH CONTROL ONLY. This,and the fact that the center of buoyancy moves forward when the ama's are planing will give the boat extraordinary resistance to pitchpoling.

8) The concept allows substantially smaller ama's and lighter all up weight than would be required without the foils and planing hulls.

Dancing me

2008-11-13T03:33:00.001-08:00

Ok I have just one a new sponsorship deal with eco, and we have produced a new promo video and you can see it here.

R Class foiler-the boat has foiled!

2008-10-31T17:54:00.001-07:00

R Class foiler-the boat has foiled! Here are some numbers:

Hull weight 63lb(29kg) plus a min. of 20lb(9.1kg) for rig and foils(probably not possible at this weight)=83lb ready to sail(nice if you can do it!)

Sail Area upwind: 140 sq.ft.(13sq.m)

Hull beam at wl(ESTIMATE) 3'(.9m)results in a L/B ratio of 4.33/1

crew ESTIMATE=320lb.(145.5kg)

sailing weight=403lb(183.2kg)

W/SA=2.87

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This ratio would allow the boat to foil upwind but in marginal conditions /light air it probably would foil after the Moth,RS600FF,M4 and Foiling 18. To bring it to the 2.558 number of the Moth either SA would have to be increased to 158sq.ft(14.7 sq.m) or the weight would have to be reduced to 358lb.(162.7kg)-leaving a 275lb.(125kg) crew.

A probable negative factor that would suggest lowering the W/SA number further is the sloop rig
Another negative factor suggesting a lowering of the number even further is the relatively wide hull at the waterline(compared to the ideal).

This boat could foil well downwind even in light air-in heavy air downwind it would need a smaller much flatter spin.

It could foil upwind in all conditions a Moth with a 180lb crew could as is. But light air /marginal conditions performance would be improved if the negative factors above are addressed by less weight and/or more upwind SA.

If only it had pods, a sliding seat, manual control and dual midship wands.

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crime against humanity

2008-10-20T04:50:00.001-07:00

There is a rumor on the blogosphere that a 16' foiler, described as a "Monster Moth" by Phil S. exists and I don't have any details.

It is a crime against humanity to keep the fantastic development work he is doing to himself. Please-for the sake of all thats good and holy-please can someone ante up with the story and ideas! The only other alternative will be to send the foil police to deal with the situation.

Ok, perhaps I'm being too "demanding"-yeah, thats it. So how about posting the pictures and info one week from tomorrow? Is that ok? Thanks.

Kiting is kiting-sailing is not kiting-kiting is not sailing.

2008-10-08T05:53:00.001-07:00

The magical 50 knots barrier fell as the outright sailing speed record fell twice in 24 hours at the Lüderitz Speed Challenge over the weekend, with French kitesurfer Alexandre CAIZERGUES recording the fastest speed of all at 50.57 knots, subject to ratification by the World Sailing Speed Record Council (WSSRC). - sailing.org

If a kiteboard is a boat then so is a waterski-absolutely ridiculous! A "boat" has to support it's load with buoyant lift at rest. But nothing can take away the kite guys accomplishment-so far(if ratified) it appears they hit 50 first-congratulations. But it is NOT a sailboat record-it is a kiteboard record.
And a kite is not a SAIL-it is a kite! In the same way an airplane is not a helicopter!

A kite can be moved independently of the"craft" it is powering to increase apparent wind enhancing power. A kite produces much more vertical lift than a sail. There is no "put-down" of kites or kiteboards in what I'm saying: it is a recognition that these two forms of harnessing wind power ARE different and should not be confused with each other in my humble opinion.

A kiteboard-carries one person only when moving -requires wind close to or higher than its top speed.
hydroptere-carries 11,000 lb of carbon + 8 people at 52knots in wind significantly less than its top speed.And it carries the same load at zero knots!

So I sent of an email and got this interesting reply from John Reed:
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Dear Doug,

The categories which can make attempts on sailing speed records are decided
by ISAF.The WSSR has no responsibility to decide whether kites can claim
the outright record.

Regards,

John Reed
Secretary to the WSSR Council
-----------------------------------
Guess I have to raise hell with ISAF. Right.... time for another email.

"I'm curious why ISAF considers kiteboarding to be "sailing" ? I think what the kiteboarders have done is phenominal but how can it be placed in the same category as a sailboat speed record?
No way is a kite a "sail"; no way is a kiteboard a boat.
So what is the rationale?
Thanks!
Sail Fast,Doug Lord"

If you have a board that is not a boat and a kite that is not a sail and yet you want to be able to claim a "sailing" speed record?! Listen, what kites have done is tremendous-but they are not "sailboats" and do not deserve a "sailing" record!!

Kiting is kiting-sailing is not kiting-kiting is not sailing. End of message.

They REALLY don't know what they're talking about!!

2008-10-05T16:54:00.001-07:00

The Bradfield planing wand has been around 8 years longer than the bow wand( which was copied from the Bradfield system) and can be adjustable-with the ratio of wand movement to flap movement completely adjustable with variations of the system including a wand clutch, adjustable bungee tension AND adjustable bungee responce.

Also, "cam" like adjustment set ups that allow variable RATES of flap movement for a given wand movement-and more-all developed by the Bradfield team years ago. And things like simultaneous fore and aft flap movement with 100% mixing adjustability, manual/wand instant switchback, manual only fore and aft systems,athwhartship angled midship wand pivot axis are being developed now(among other very interesting technical tidbits you will hear about in a while).

1) from seahugger mode to flap neutral the wand tip moves 62.5% of its max travel
2) from flap neutral to max flap up the wand moves 37.5% of its max travel

That gives much finer flap control from 10 degress flap down to 2.5 degrees flap up with much quicker reaction above 2.5 degrees up-something that is required on the Rave since the foil pulls down as well as up and is symetrical set with a 2.5 degree positive angle of incidence to the static(design) waterline.

So, you see, it pays to think(or at least check out the facts rather than guess) before you speak........

And,oh yes: a high priority on jumping with 100% successful re-entry.

the ultimate kickass 2 person boat

2008-09-11T23:20:00.001-07:00

Many have tried and are trying to convert existing two person dinghies to foilers but have you ever wondered what a two person foiler designed from scratch as a replacement for,say, the 49er might look like?

Here ya go:
LOA= 18'(5.49m)-no gantry
Hull Beam@ wl=1.6'(.49m)
L/B=11.25/1
Beam OA= 6'(1.8m-includes very small buoyancy pods)
Allup boat weight=154lb(70kg)
Nominal Crew Weight=320lb(145.5kg)(twin trapezes)
Sailing weight=474lb(215.5kg)
Sail Area=185 sq.ft(17.2sq.m)(main only-reefable rig)
W/SA=2.56(equal to or better than Moth,same vicinity as M4,I14(Lugg),Foiling 18)
SCP/total weight= 45%
SA/ws hullborne and foil borne greater than or equal to Moth
Retractable foils

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Approx 50% of the hull/deck area of a 49er-less material-less cost
Approx 122lb(55.5 kg) less weight than 49er-less material-less cost
Approx. 44sq.ft less SA than 49er upwind. No Spin(light air code zero?)

---- With Manual controls and a retractable, sel-frighting K-Bulb, This boat could be MUCH faster than a 49er if carefully designed and engineered. And cost less.

The case for the midship wand

2008-09-10T00:43:00.001-07:00

A midships wand is definitely better than a bow wand in flat water because it can be significantly lighter if the Bradfield system is followed.

In chop with a forward wand there is a delay between wand activation and the foil being where the wand was when activated of around a quarter second at upwind speeds in addition to wand response(bungy) lag. This intereferes with the ability of the forward wand to average it's inputs.

The midship wand has only bungy lag and therefore has a quicker and more reliable response to begining to average wand input resulting in a steady altitude and less of a likelyhood of dramatic flyouts from waves. This can be seen on the Rave video in the rapid movement of the wand which is noticeably more than on a Moth in similar conditions as best I can tell.

This is very important: Because the forward wand's center of lift(drag) is significantly displaced from the boats center of lift when flying there is another element added to the forward wand response and that is pitch coupling. This can add or subtract from the wands response-when it adds the boat flys out of a wave. That happens much less frequently with fewer consequences on a boat equipped with a midship wand where there is NO PITCH COUPLING whatsoever.

So the combination of the midship wand developing an averaging response quicker than does a forward wand and the pitch coupling common only with a forward wand explains very well the observed responses of both boats and seems to suggest that a well designed planing wand mounted midships might be an improvement on a monofoiler in every conditon.

At 22 knots there is no 'anticipatory' or 'reactionary' wand-just an averaging system with fairly rapid wand movement on a Bradfield system.

The bow wand would be subject to unanticipated moves due to pitch coupling as mentioned earlier. I'd bet that the midship wand would be -by far-best in these conditions.

The question about foil spray is one of the best yet. On the Bradfield system the wand is next to- not in line with -the foil and is not affected by the foil "spray" in any way. But in applying the Bradfield system to a bi-foiler the wand will need to be close to the center line and the foil wake and/or spray may or may not have some effect.

The Japanese Mothies are experimenting with an in line trailing wand system similar to the ones used for many years in human powered foilers(very successfuly). That type of wand does not have the power of a Bradfield type and yet has worked very well despite being located behind the vertical fin.I'd imagine that the Bradfield type would work well-I'll know before too long on my boat. It would be interesting to see three equal Moths rigged with the standard ,Bradfield type and Japanese type.

The problem with the bow wand seems to be that it can produce movements of the flap unrelated to the averaging of the wand.Depending on whether it adds to or subtracts from flap movement the average wand movement can result in unpredictable and sudden big movements of the flap.(Probably exacerbated with flexible wands)

This kind of pitch coupling can't occur in the Bradfield system because the wand makes contact with the water at the center of lift of the boat so there is no pitch coupling at all.

Unless the wavelength is so great that the boat contours the averaging occurs when the boat platforms and results in rapid wand movement(several times per second) while the boats altitude remains the same. In wave conditions where the boat is platforming the wand reacts multiple times per second and the forward wand anticipates nothing-in fact there is some reason to believe that in those conditions the separation between the center of lift of the wand and center of lift of the boat is not a positive thing at all-contributing to erratic behaviour. Flexible wands would tend to agravate the problem-both in averaging and with pitch coupling. Depending on whether the wand is a planing wand or not, conditions can make the ride feel like a bumpy road in short steep chop.

One thing all this recent wand study has done is reinforce 100 times over the fact that a manual system that mixes main foil control with rudder foil control will be superior in racing. Wand movement at multiple times per second reduced to virtually no movement! When the wand is averaging it is essentilly creating major changes in the lift coeficient of the foil rapidly and for no net change in altitude. This is a drag producing machine!

Manual control will be fairly hard to learn to race well but the potential savings are much greater that I thought just a few weeks ago.

You can't handle the truth

2008-09-08T20:48:00.001-07:00

So every day I have some idiot telling me "pics or it didn't happen" or "you have never foiled". Well enough is enough. Just because I have never been seen foiling doesn't mean I haven't done it and here is the proof.

Why haven't I shown this before? Well the photo is out of focus, and blurry, and who wants to see an out of focus blurry picture?

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So now that people can't call me up on the 100% proven part, what will they say now?

Foilers for big guys

2008-09-08T05:32:00.001-07:00

Here is a pix of David Luggs I14 being sailed on two foils but using manual altitude control instead of a wand:

If you go to boatdesign.net and look under John Ilett in the gallery you'll find more pix of 14's on foils using Johns wand system for altitude control. There is absolutely no reason why larger monofoilers can't foil and foil very quickly esp. if the foil loading, SA and RM are paid attention to. Numerous people all over the world are experimenting with and actually sailing larger two foil monofoilers.But the one unassailable fact is that the Moth has led the way in developing effective monofoiers and ,in particular, the two foil hydrofoil systems. Before that, for decades, foilers always had three foils.I'm 100% confident that bi-foil technology can be applied to much larger boats including such boats as the "Maxi Skiff's" conceived of by Julian Bethwaite and Sean Langman.

To say that larger boats can't foil upwind is just plain wrong. From an article by David Lugg in the May 2002 issue of Australian Sailng:"The first compromise was to reduce the foil size so that the hull did not leave the water at upwind speeds. Early experiments with larger foils HAD THE BOAT FOILBORNE UPWIND WITH EXCELLENT SPEED but greatly reduced pointing ability." That was 2001!!! And using a manual altitude control system! All this before anybody knew the techniques that would be developed by Rohan to fly fast upwind. Imagine if the class had not banned full flying hydrofoils!

There are some guys that have relatively recently used modern Ilett foils on 14's in Switzerland and I don't know their results yet.

But it is nuts to say that larger, heavier boats can't foil upwind! If you want to talk "boats" instead of just monofoilers I've sailed a Rave multifoiler upwind in 12-15 touching down for a split second while tacking. And I'm heavy! As to monofoilers: since we know it can be done it is only a matter of time before a boat suitable to singlehand heavy(190-220lb./86-100kg.) people or two people becomes a reality. If the numbers are done well keeping SA, RM and foil loading in the right range with an efficient rig these boats will foil early and well-upwind or down-no doubt about it!

But no matter what happens in the future monofoiling as a practical race winning technology started with the Moth Class and is probably one of the most historically significant developments in sailing in the last 100 years.

++++++++++++++++++++
According to the Johnson 18 statistical reference page the 49er has 2.68 times the sailing weight of a Moth
and 2.65 times the Sail Area of a Moth (upwind). Definitely in the ball park. Crew weights based on 160lb.s(72.7kg's). In designing the Peoples 2 person foiler you wouldn't need the huge asy spin of the 49er or the wide heavy(263lb./ 119.5kg.) hull of the 49er and ought to be able to knock 68 pounds(30.9kg.) off the design for a two person foiler. It's right there staring us all in the face-thats why in an article in Seahorse magazine Ian Ward, another great Moth pioneer, proposed a SERIES of monofoiler classes! This is a revolution in SAILING not just in the Moth class....
====================
Moth with 160lb. crew;all up 220lb.s or 2.58 lbs. per sq.ft.SA.
---
49er with two 160lb.;all up: 583; crew=2.55lb.s per sq.ft.SA
----
Peoples foiler(modified 49er) 2 160lb. crew;515 all up; 2.25 lbs/per sq.ft. of Sail Area or dramatically better than a MOTH almost(depending on rig)guaranteeing upwind foiling in light air!
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Don't tell me it's not possible.....

aeroSKIFF 14

2008-09-07T00:15:00.000-07:00

Features of the aeroSKIFF 14:
TARGET SPECIFICATIONS / aeroSKIFF 14 / based on 250lb. max crew-drawings in post 15 based on 220lb. max crew.
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1) LOA 14'8" Beam 12'(drawings in post 15 show 10' beam-beam may be increased to reduce buoyancy pod size and to help make crew weight range wider)
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2) Target ready to fly boat weight: 120 lb.s
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3) Max Crew 250lb.s ; target minimum crew 120lb.
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4) Flying weight: 370lb.s
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5) SA 143 sq.ft. square topped, camber induced , main only, unstayed mast ,extended luff, modified wishbone, midboom sheeting.
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6) Standard main foil area 1.68 sq.ft.
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7) Mainfoil loading @ 80% 176lb. sq. ft.
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8) Rudder foil area 50% mainfoil area.
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9) SA/mainfoil area: 85sq. ft. per sq.ft. foil area.
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10) "Wing Loading"( all up weight divided by SA) =2.58lb.s per sq.ft. SA.
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11) Draft ,off foils; foils extended= 3.75'-variable.
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Features
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1) Forward third of sail comes completely down to the deck; the boom is a modified version of a wishbone boom with a cross member just forward of mid length that takes the mainsheet. The sheet is led to a traveller on the forward beam allowing the sheet to come from forward. A twin vang set up will be used should a vang be required.
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2) Foils retract to facilitate beach launching.
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3) Sliding single bench seat; slides easily and contains ballast compartment for one design class weight equalization system.Motion control system that prevents runaway seat in adverse situations.
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4) Standard foils optimized for low speed takeoff; optional tip extentions; optional high speed foils.
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5) Buoyancy pods approx 1.56 cu' per side; larger optional pods available for training.(see approx 3 cu. ft. pods illustrated in the sketches in post #15)
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6)Rudder: unique design slides up and down in daggerboard style slot; stepped rudder flap designed to allow variable rudder area between non foiling and foiling; Target is to have rudder throw and sensitivity the same on or off
foils.
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7) Double ended hull facilitates earlist 0 to takeoff; facillitates pitch change to allow early takeoff though foil system may not require this.
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8) Trampoline each side with heel cutouts allowing quick, secure seat movement.
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9) Foils designed to take loads imposed by jumping which can be initiated by twisting hiking stick(s).System bypasses wand but still utilizes forward /rear foil interconnect.
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10) Variable main foil "gear shift" angle of incidence adjustment. From "set it and forget it" to fine tuning main foil drag.
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11) Exceptionally wide crew weight range ; one design cass races wil be sailed at the 250 lb.s crew weight. Speed runs will be able to be made with lower crew weight as long as RM is addressed.
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12) Wand controlled altitude with height adjustment. Set it and forget it or tweak it. Unique averaging wand system to improve choppy water response including fore and aft foil interconnect and wand bypass for smoother flying and better jumps.
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Jumping is an important part of this foiler design because we think it will add to the value of the boat and to the fun of flying this foiler.

foiler weight

2008-09-05T17:48:00.001-07:00

So many experienced foilers have been deluded into thinking that to have an effective singlehanded foiler it had to be all carbon and cost a fortune because they believed that WEIGHT was the single most important factor in foiling. IT IS NOT!! The most important single factor to determine "foilability" is not weight but the "Sail Loading"(weight divided by sail area).

RS600FF all up ready to sail weighs AT LEAST 167 lbs. That is 2.53 times MORE than a MOTH! Repeat, the RS600FF weighs ,ready to sail(minus crew), 2.5 times what a Moth weighs, ready to sail(minus crew).

There are other factors that will contribute to a foilers speed around a course,of course. But no single factor is as important as this power to weight ratio:
1) weight/SA on the RS 600 with a 160 lb. crew= 2.49 lb. per sq.ft.SA
2) weight/SA on the Moth with a 154lb. crew(Rohan)=2.558 lb. per sq. ft.SA

This means that even though the RS600FF is 2.5 times,repeat 2.5 times, as heavy as a Moth in racing trim with a crew it has a BETTER power to weight ratio.

Again, this is very significant for the eventual introduction of a reasonably priced peoples foiler. And it flys in the face of the constant drumbeat from some Australian (and other) foilers and foiler wanabes that weight is the single most critical factor-it is not.

This is big ,guys -in many ways starting with the fact that you DON"T NEED AN ALL CARBON HULL. Think how that could reduce costs. If a boat was built with a hull having a length to beam ratio like a Moth with a bigger rig like an RS but better aerodynamically like a Moth rig it could be lighter than an RS and be built from less expensive materials. Not speculation or theory: PROVEN FACT!

A Peoples Foiler could easily be configured for very light wind takeoff, or very high top end speed -probably with the same foil set with removable tips. As to pushing the limits I believe I am one of the first people that have ever suggested that jumping a foiler intentionally with a boat designed for it might be A LOT OF FUN.

There is a lot of room for a carefully designed easy to sail, beachsailable foiler. The design constraints are much less stringent than people like Phil, SimonN and others have been saying. And the RS proves it beyond a shadow of a doubt: weight is NOT the major determinant of a foilers success-the power to weight ratio is(among other factors).

Now isn't that sexier than a girl in good shape in a quality bit of lingerie under her little black dress?

BMW ORACLE Racing monofoiler

2008-09-04T07:39:00.000-07:00

you can't deny the proof the new BMW ORACLE RACING boat is the worlds biggest monofoiler.

This photo shows how well the buoyancy pods work, and you can see the guys in the steering pod who are operating the manual foil controls.

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My 16' foiling keelboat

2008-09-04T06:27:00.000-07:00

So here is a sneak peak at the keel of my 16' foiling keelboat. Allup 160 +120lb keelbulb+ the sail area to foil off wind with a better POWER TO WEIGHT RATIO than a Moth. It's this ratio that counts-not just weight. Of course, the thing has to be designed very carefully for it to work as mentioned earlier.

ultimate family daysailor

2008-08-30T21:42:00.000-07:00

I'm very interested in comments about the concept as a boat and as a product. It is a dinghy with a small keel; it is not a sportboat. Closest to it is the Laser Stratus except that this is half the weight and the hull is much narrower. It only foils DOWNWIND, has manual controls and is built for JUMPING.
This be the ultimate two person boat/family day sailor.
LOA 16-17'
Beam 12' (easily foldable for trailering)
Hull+ rig ready to sail weight 160lb.(minus ballast)
Ballast in bulb keel-120lb(self-righting from capsize or pitchpole) only etc.
Crew weight nominal 320lb.(sliding bench seat)
Upwind SA 150 sq.
Downwind SA 300 sq.ft.
Mainfoil on keel strut(at bulb)
Rudder foil

-----------------------------------
----Idea is to provide a safe, very fast two person boat that would be designed to foil down wind: round the mark,pop the spin,deploy the wand and whoosh....
----Uses modern ideas from several different types of boat to provide a new kind of sailing experience. Could be configured in a number of ways-for instance single handed main + spin only. Four people (2 adults, 2 kids main+ jib daysailing only).
Design configuration for racing: Two people ,max 320lb (more or less).
----Sliding bench seat P&S-NO HIKING NO TRAPEZE.
---- Manually controlled 100% self righting
----Power to weight ratio off the wind better than a Moth.(W/SA=2.0)
----Small buoyancy pods on outboard of rack

Regular readers will note this is different than my other designs because the numbers are different and this one includes 100% automatic self righting with manual self riighting controls; and the buoyancy pods are smaller.

hope it is adjustable

2008-08-29T23:52:00.000-07:00

Is the f-box adajustible when sailing or not?

A fistfight broke out today in sailing anarchy over adjusting the fbox. It was this is very interesting-what in hell was going on? One guy says yes the other guy says no??!!

Damn, its a good idea-hope it is adjustable.
* if it was designed right it would surely work well....

eliminate the gantry

2008-08-23T00:07:00.000-07:00

The gantry (in my opinion) is a rule induced abberation which is NOT necessary for a successfull foiler design. In fact, there are really good reasons why it should be eliminated:

1) by allowing the hull to be a bit longer the available hull buoyancy is increased so the L/beam ratio can be increased reducing resistance and allowing the boat to achieve takeoff a bit sooner.

2) In my humble opinion, it is somewhat ugly and help creates a "contraption" appearance to some onlookers.

3) When taking off without an F-box(angle of incidence control) a gantry (and transom)drags when the boat is pitched bow up.

4) The ONLY reason for a gantry is to allow the foil footprint to be better on a boat NOT DESIGNED FOR FOILS IN THE FIRST PLACE.

A Peoples Foiler at last?

2008-07-13T20:09:00.000-07:00

From Adam May:
"Oh and Linton's latest foiler - a more of a foiler for the masses was also out yesterday evening. I didn't get any pics of it foiling, and few details are known about it yet so I'll save that for another post if I can find the time." http://foilborne.blogspot.com/

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Also a mystery foiler was seen with a jib in Weymouth 7/13/08

I wonder if they are using manual control? Any true peoples foiler will need it, especially when jumping.

Repeating past glory

2008-07-12T15:57:00.000-07:00

Well the X21 is moving along-Time to work on it is a strruggle between my internet forum posting commitments. I was quite suprised the other day when someone brought up my past success the Kona Kat.

Building the Kona Kat was a great experience despite the idiots that said it was completely pointless and that it would be slower and heavier than a windsurfer.

Well we showed them-we sold 180 units and I got my first patent for the cone-shaped member.

Sport Boat Foilers

2008-07-12T06:30:00.000-07:00

With the phenominal new Super Foiler Mirabaud making history NOW it seems like a good time to revisit these ideas I've thought about and worked on for several years:

There are some really exciting sportboats available now and at the end of this post are some interesting websites particularly the one with comparison statistics of a few current boats. For purposes of this post I'll define sportboats as high powered keelboats between about 20' and 40'. Some boats are much higher powered than others as you'll see in the comparison table. They should be able to plane (or foil). Ocean racing versions should be self-righting.
After doing an exploration of the feasibility of a foiling 60' monohull keelboat, it occurred to me that the next big advance in monohull foiling would probably be with a boat that fits the definition of sportboat so I 'm presenting very preliminary numbers for a two person and three person "Sportboat Foiler":
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Two Person
---LOA 24'
---LWL 24'
---Beam 18.6' (overall, incl. racks)
2.4' at waterline
---Draft 6.5' keel,foils retractable
---Sail Area 586sq.ft. upwind and downwind
---Boat weight,incl. rig and ballast-1100lb.
---Ballast 490lb. (110° canting keel) 44% ballast/displacement ratio w/o crew
---Displacement (incl crew)-1420lb.
crew-320lb.
=================================
Three Person:---LOA 24'

---LWL 24'
---Beam 10.73' (overall incl. racks)
2.4' at waterline
---Draft 6.5' keel and foils retractable
---Sail Area-600 sq.ft. upwind and downwind
--- Boat weight- including rig and ballast-1100lb
--- Ballast 490lb.( 110° canting keel) 44% ballast/Displacement ratio w/o crew
---Displacement, incl. crew 1580
crew-480lb.

=========================================
Three Person FIXED KEEL SELFRIGHTING
---LWL 24'
---Beam 18' (overall incl. racks)(2 on trapeze optional)
2.4' at waterline
---Draft 6.5' keel and foils retractable
---Sail Area-650 sq.ft. upwind and downwind(except in light air then 1200 downwind)
--- Boat weight- including rig and ballast-1100lb --- Ballast 490lb. 44% ballast/Displacement
ratio w/o crew
---Displacement, incl. crew 1580
crew-480lb.[/color]
Take Off Boat Speed is 6.5 knots which would be achieved in a 6-7 knot wind with 650sq.ft SA
Configured for early take off using a 63412 section at a mainfoil angle of attack of 6 degrees and a 20 degree mainfoil down flap angle.

=========================================

Other comparisons:
-- -Sail Loading(weight divided by SA)- Two Person=2.42 lb. sq. ft. ; Three Person= 2.69 lb. sq.ft.; Three FIXED 2.43(#2 & #3 this ratio better than a MOTH)
---Mainfoil Area- Two Person=7.1 sq.ft. ; Three
Person= 7.48 sq.ft., Three Fixed 7.64 sq.ft
---Mainfoil Loading- Two Person=158lb. per sq.ft.
Three Person=169 lb. per sq.ft.
---Sail area per sq.ft. mainfoil area- Two Person =82.5 ; Three Person=80.2 ; Three Fixed=86.8
Note: Two person takeoff profile is approximately equal to a Moth with Rohan Veal aboard;
Three Person approx. equal to a Moth with a 160lb. person aboard.
---D/L Two=45.6 Three= 51
---SA/D Two= 74.3 Three=70.9 Three Fixed=78.4
---SCP/total weight Two=42% Three=34% Three FIXED 38%
===============================
Three person fixed keel would be 100% selfrighting w/o crew interaction:BALLAST/DISPL. RATIO SIGNIFICANTLY BETTER THAN T780. Ballast in this keel is not used for sailing RM-just for RIGHTING. Boat sails with 20 degrees veal heel adding 21 % to RM.
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Both canting keel boats would be designed to be rightable by moving the keel; and a 100% self-righting foiler(no crew action required) is possible------------------
Weights for the hull and rig were derived from EXISTING boats that have hulls ,for the most part, twice as wide with over double the area anticipated with these boats. The hull would be very narrow -not much over three feet wide(at the deck) with possible flare out forward for a minimal cuddy cabin. The hull would be double-ended. In comparisons with the other boats in the table below the Sail area to wetted surface ratio of both versions above is probably greater than any other boat even INCLUDING the wetted area of the hydrofoils.(8.27/1 vs. 4.7/1 for the Martin 243).

I did this to show how incredibly close we are to having one of these boats actually built; the technology required to do this is available now and I hope it won't be long before "Flying Keelboat" really means flying...

Foiler 18vs "Normal" 18

2008-07-11T16:02:00.000-07:00

Thomas Jundt sailed the 18 europeans with his 10 year old 18 with foils -not Mirabaud. I thought their chances were pretty poor sailing a 10 year old wide 18 converted to a foiler. In no way is this ideal or representative of the utmost in bi-foil technology. A skinny hull would be faster especially in marginal conditions. If "rules" weight would make the "new" foiler 18 artificially heavy -then fuck the rules-the point is to demonstate the technology-not antique rules.

Let me summarize it-as I understand it: when there was wind the foiler kicked ass. A foiler as light as the newer 18's would have probably kicked ass on and OFF the foils-particularly with a big lite air spin.

Thomas sent me an email and here is what he said about how he went.

In none flying conditions we are slower (the second race) :
- a bit slower upwind, the additionnal drag of the foils seams not to be too penalizing
- but much slower downwind, our head sail was a 20 sqm code 0, way not enough against the 65 sqm assymetrics

My conclusion :
- dispite the fact that our boat weighs 220 kg compared to the newest ones at 155 kg (class rule minimun since 2005) we are competitif when foiling (wind at least 10 knots)
- the additionnal drag of the foils seem to be acceptable when non flying
- in non foiling conditions downwind without the big assymetric you're dead
- a new boat 155 kg, with foils in the hands of a trained crew would beat everybody by a big margin in most conditions
- unfortunately, foilers seem not to be welcome in the class

Regards
Thomas

I'm not sure that with all the rancor there is-like outright hostility to Thomas at the Euro's-the 18 foiler class will develop. The Moth class has shown that seahuggers and foilers can co-exist in the same class. It would be a shame if the 18 class doesn't embrace foilers-a new class may result that will be much faster than the current boats. If thats the way it has to be -so be it.......

The potential speed of the FOILER 18 is huge! According to Rhoan Veal A Moth in the right hands can beat current 18' cats(that have repeatedly beaten 18 skiffs).

"Each race of our division started 5 minutes behind the F18's, but by the end of my three laps, I had nearly caught and passed most of them. The highlight was passing them one at a time (to windward and leeward) on a reach with their kites up! Only a few of the top guys on a Tornado and Hobie Tigers stayed ahead, but they wern't anymore than 2-3 minutes in front. Needless to say I am feeling extremely confident with my Mk4 Prowler now that I have all the configuration and teething issues sorted out. It took 8 months, but I think Moth development is a case of one step backward, and two steps forward. "

Anecdotal evidence for sure, but when combined with what Thomas Jundt says shows that a FOILER 18 designed from scratch as a foiler would beat the crap out of ANY boat its own length.

A few people I've talked to think a the next big area of foiler development will be a two handed foiler. I agree if it is designed from scratch as a foiler-and not a coverted I14( or converted anything). Converted 14's on foils (and Mirabaud):

My first BLOG post

2008-07-11T07:47:00.000-07:00

Since everyone else is BLOGGING about their foiler achievements, I thought I should too. First some history. Most people that know me keep asking what I have been sailing. Here is the list in no paricular order

======================

windmill(many firsts incl District Championship), thistle,fish class(many lasts and a few firsts),hobie 14,hobie 16,e scow, US 1(several 1sts etc),14'high performance experimental tri, 16' experimental cat,20' high performance experimental tri,TS 18(80+),Kona Kat (about 180) aeroSKIFF One, aeroSKIFF 2-X21-T(as we speak),worlds first production rc sailing multifoiler,worlds first rc monofoiler(as far as I know),worlds first production rc spinnaker boats,worlds first video piloted rc helicopter, 4 US patents including K Foil,"3D SAILING" trademark(sold),numerous other trademarks. Several new patents in various stages on foiler control systems.
www.microsail.com
www.monofoiler.com
Oh, yeah: learned much from Dr. Sam Bradfield and a book or two......