NorCalNomad wrote:You must not have seen too many mast as a 2 axis symmetrical foil shape isn't as efficient as say a symmetrical naca shape. I have yet to see a carbon mast with a 2axis symmetrical foil.
Actually what I've seen have not been completely symmetrical 2 axis, but however thickest point is quite near at the center. Look how Denisesewa's mast profile has changed to that direction. For my eye your mast hydrofoil looks a bit too blunt at front area. But if you have finished your mast its ok, no doubt it works.
Of course mast profile must be symmetrical chordwise, so no cambered. There might be some cavitation or stiffness related reasons why generally used mast hydrofoils are what they are. I have seen four hf's at close range and many more in forums, no big differences in that relation.
Thinking dragwise and based on aerodynamics I agree what you wrote about efficiency - but is this so much different world that this knowledge is not valid?
Big differencies to aerodynamics are: 1)water is over 800 times as dense as air 2)used hydrofoils are very small by their size.
NorCalNomad wrote:It's pretty easy to make a laminated structure far stiffer than an alum. one as long as you know some basics of your forces, lamination, and layup processes. Should even be not that hard with a male mold that also adds stiffness to your part.
I am not sure that Alu vs. carbon stiffness in DIY practice. Some aluminium alloys are very stiff, when heat treated etc., in every direction. Laminating on male mold (wooden core, foam core etc) doesn't add stiffness much, because the surface takes most of the loads. That is why foam core is at all reasonable.
Easiest way to increase stiffness is to add diameter. I read from kbhf forum calculation of decreasing mast thickness some mm's (about from 20mm to 15mm) would give knot or two benefit over 20kn speeds - for a beginner these speeds are too much... Of course for racers it is a big difference. Here local hydrofoilers fear high speeds (or crashes) they can reach with their hf's.
#apartmentlife sometimes is a real bitch.
