It's only a model

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

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?
-------------------------
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?

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

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!

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

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



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.

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

crime against humanity

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.

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:
----------------
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!!

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.