rick--

just a point of clarification. you mentioned "ww hull" four times in the passage below, but "lw hull" only once. is this a typo?

in square brackets is what i think you meant. please let me know if this is correct.

very interesting stuff!!

ben

> The shape of the windward hull is the lowest drag displacement hull
> for 6kts carrying 200kg having a flat bottom.
>
> The ww [LW??] hull is the lowest drag displacement hull for 200kg at 16kts
> with a flat bottom although at that speed and load it will be planing
> so the displacement aspect is somewhat meaningless at that point but
> it has to get there and above.
>
> The ww hull ends up longer than the lw hull for this size boat based
> on my starting point.
>
> The shapes are distinctly different and highlights the advantage of
> the proa configuration over a catamaran. The fine entry and long
> waterline length on the ww hull reduces wave drag in displacement mode.
>
> The full bow and deep draft of the ww [LW??] hull works to reduce wetted
> surface when viscous drag dominates overall drag at high speed. The
> full bow gives high KMl for the waterline length and the wave
> pressure at the bow creates buoyant lift once under way. This nose-up
> attitude assists transition to planing.
>
> Both hulls have narrow flat bottoms that will plane at shallow angle
> of attack once speed gets over 10 to 12 knots. This means the lift
> to drag is high once in planing mode. There is no hump to planing
> just a gradual transition.