No I produced a reasonably shaped 20' V hull for 400lb dis. 30'' sheer height, 20'' beam, that sits on a 14'' draft. With a 10'' waterline beam

Square hull bottom 20' hull 20''sheer height,14'' beam with a 14'' waterline beam.

V and Square bottoms are both flat panels/slab sided. Why do you think the larger cross section would be more efficient just because of its lift coefficient?

V hull with greater lateral surface area on a smaller narrower cross section is efficiency. Requiring even small boards for steering vs lateral resistance.

Todd

--- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@...> wrote:
>
> Todd
> The V hull will produce lift but nowhere near as efficiently as a
> cambered centreboard. I also doubt that it will be more efficient
> than a flat bottom hull. Using your numbers you have increased the
> wetted surface more than 30% just to increase the lateral surface
> area. There is a huge cost in terms of extra hull drag. The lift
> coefficient for a deep V section could easily be half that of a flat
> panel. So 18sq.ft V may not be any better than 7sq.ft flat.
>
> I have some reasonable models for flat panel planing and Savisky for
> planing V hulls but it stops at 35 degrees deadrise for vertical
> lift. I know anything steeper than 45 degrees deadrise will dig in
> rather than slip sideways. So if the deadrise is greater than 45
> degrees it should be good at preventing leeway but still not as good
> as a slab side.
>
> Rick
>
>
> On 16/05/2011, at 2:11 PM, tsstproa wrote:
>
> > Hull length for length. Hull displacement for displacement.
> >
> > Say on a 20 foot hull with a 400lb displacement.
> >
> > V hull with a 13'' draft and Square bottom hull with a 6'' draft.
> >
> > V hull 38sqft wetted surface area, square bottom hull 28sqft wetted
> > surface area.
> >
> > V hull with 18 sqft lateral area and Square bottom hull 7 sqft
> > lateral area.
> >
> > V hull skidding out and not producing lift I doubt it!!!
> >
> > V hull with more than double the area how do you figure it would
> > and not produce lift?
> >
> > Also at high angles of heel do you see the difference in under
> > water plane shape? The wider the square bottom hull becomes the
> > more defined is becomes.
> >
> > Placement of rudders on beam is more about convenience for the
> > models. The rudder placement on the model in this clip is to close
> > to the hull. If you look at the end of the clip. The same model
> > with the reverse flow sail design on it you might see what looks
> > like rudder ventilation. I use rudders to test balance of hull to
> > sail. Not to test foil designs. Except of course the large leefoil
> > and windward foil design models.
> >
> > Todd
> >
> >
>
> Rick Willoughby
> rickwill@...
> 03 9796 2415
> 0419 104 821
>