High-Speed Sailing

I was looking at Wotrocket's video to see if I could learn anything interesting. While there is not a lot to go on, here are my observations of what I saw. They do have a visibility problem (spray blankets the canopy). This is due to two factors: one is the shape of the crew pod - it's short and fairly blunt, the other is the wind swell/chop they were operating in. If they sail in smooth water, they will have less of a spray problem. I suggest extending the nose with provision to deflect spray away from the canopy. Naturally, the intention is to fly the crew pod, at which point there will not be a spray problem but ya gotta have good control to do that.

Near the end of the video as the craft gets powered up, it looks like the lead hydrofoil lifts the nose of the craft and then the craft appears to rotate off the wind a bit, lose lift, causing the nose to crash back to the surface, submerge and pitch-pole the boat. The fact that the boat rotated off the wind leads me to suspect that the vertical strut of the nose foil was lifted far enough out of the water that its "side bite" diminished, causing it to drift sideways. The boat is being "squeezed" between the water pressure on the vertical hydrofoil struts - one fore, one aft and the air pressure on the wing. If side bite is lost on either strut, the craft will rotate (yaw). It also looks like they had pretty much lost roll control as the crew pod was too high as well.

I've had experience with something similar, in which I'd placed a hydrofoil under each of two pods. The hydrofoils worked great and lifted the pods out of the water but then went across a wave trough, hit the next wave enturbulating the water flow, lost lift and crashed the pod back to the surface. I had no control problems, but the boat would slow every time it hit the next wave (wind swell/chop).

Hydrofoils do pose a problem for pitch control because they have to maintain a constant distance from the surface and there is very little margin for error. Trifoiler (which see) has a great solution, but there are other ways to do it. No matter how done, pitch control will have to be automatic. I do not know how Hydroptere controls pitch but would like to find out.

Bob