Saturday, February 7, 2009

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

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?

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