I think volume is important for the lowest wind. A planing craft goes from being fully supported by buoyancy (dependent on volume) to fully supported by hydrodynamic force (dependent on area). For a kiteboard, planing starts around 6 knots, but it's not all planing or all buoyancy, it gradually goes from one to the other.BWD wrote: ↑Fri Oct 27, 2017 6:02 pmWhat about volume? 10-12L seems enough to float almost any foil so it won't sink, but gives challenges starting in light wind. Double that and the sinking when starting will be slower. If the board has a wide shape, it will also sink more slowly, even if volume is not great. To me volume seems even more dependent on taste and specific use than shape, and definitely more than surface area, which seems to follow some basic hydrodynamic principles.
You can get going with no volume at all, but it takes more power to jump up to speed fast enough. When I get to the lightest wind to kite in, I'm usually standing on the board and between loops or dives I'm not moving at all, so volume and the kite are all that is keeping me up.
When getting on plane, the drag is directly proportional to the trim (tail down angle of the board). The longer the board, the more level you can ride it, and the less drag you will get while getting on plane.
I don't think speed boat hulls are a good place to look for efficiency at getting on plane. They have very high power to weight ratios and designed to minimize drag at super high speeds.revhed wrote: I was referencing SHAPE as posted, but sure like his thinking ala speed boat hulls.
I'm kinda skeptical of the hoover board, but then again I've never tried it so who knows It makes sense that the skegs on the side make it not yaw, but I don't see why it would make a difference in stability or drag. If the skegs are submerged, they won't affect stability. Stability (Metacentric Height) is determined by the waterplane area. Air entrapment and air lubrication are things that have been tried with limited success on planing boats, but usually it's for high speed stuff. I'd love to give it a try sometime though!