Sorry sent before finished.

I see the evolution to a low displacment low draft designed hull would benefit from Your highly defined foil shapes. Send me set $$$

Time for me to build a different leeward hull.

Todd

--- In harryproa@yahoogroups.com.au, "tsstproa" <bitme1234@...> wrote:
>
> The design of the deep V is suppose to do that lift hull to windward when slightly heeled. Taking that into consideration small boards low aspect rounded edges flatish profile low lift low drag.
>
> --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@> wrote:
> >
> > Todd
> > On you last statement regarding the lifted tack. That is what I am
> > talking about with the trim adjustment. The rudders are set up to
> > give you more lift then you need for some conditions. They are
> > dragging the hull sideways into the wind. So you have the rudders
> > fighting the hull, creating unnecessary drag. Inevitably it will be
> > faster to go where you point rather than ending up higher than you
> > point.
> >
> > Rick
> > On 09/08/2010, at 11:06 AM, tsstproa wrote:
> >
> > > Knowing you need aoa for best flow on different types of foil
> > > shapes. The foil that needs the least amount of aoa for best flow
> > > is again a compromise to over come the drag you describe as
> > > opposing force from each board if in deed this is the case.
> > >
> > > The whole design goal of the linked boards hung on center chord was
> > > just that zero aoa for best possible flow, speed, along with a
> > > neutral helm. How controllable the set could be and what if any
> > > negatives there where. Everyone I talked to said the rudders would
> > > be over balanced and the set up would be uncontrollable.
> > >
> > > So far in most all my shunts leeway is not even an issue. I'm am
> > > almost always on a lifted tack after a shunt.
> > >
> > > I think its about refining the compromises. Not replicating the all
> > > ready known.
> > >
> > > Todd
> > >
> > > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@>
> > > wrote:
> > > >
> > > > Todd
> > > > With your AR around 2 they will have a best lift to drag just under
> > > > 10. If you were to increase the AR to 4 then the best L/D is just
> > > > under 15.
> > > >
> > > > To get the full benefit from the asymmetry you need to be able to
> > > > trim them with respect to each other. You could set them up for
> > > > close hauled but then they will have more lift AND drag than needed
> > > > off the wind.
> > > >
> > > > They have similar performance to a NACA0010 section. The minimum
> > > > drag is about 20% lower than a NACA0010.
> > > >
> > > > Rick
> > > > On 07/08/2010, at 4:25 AM, tsstproa wrote:
> > > >
> > > > > RG14 mirrored...
> > > > >
> > > > > --- In harryproa@yahoogroups.com.au, "willoughby_rick"
> > > > > <rickwill@> wrote:
> > > > > >
> > > > > > I have posted the co-ordinates for the best L/D rudder section I
> > > > > can come up with for AR of 4 and Re# 10E6:
> > > > > > http://www.rickwill.bigpondhosting.com/NACA_07-310.txt
> > > > > >
> > > > > > It is worthwhile noting that if the AR is not limited
> > > > > structurally or by draft then the best L/D section will get
> > > > > thicker. So if someone wants to play and can handle higher AR then
> > > > > I can go through the exercise.
> > > > > >
> > > > > > The best L/D for this section occurs between 0 and 0.5
> > > degrees AoA.
> > > > > >
> > > > > > It is VERY important to realise that they need to be able to
> > > have
> > > > > relative angle trimming. If the boat goes best on the wind with
> > > the
> > > > > combined trim greater than 1 degree into the windward side then
> > > the
> > > > > blade area is likely too small to get the best L/D. Typically
> > > these
> > > > > rudders will have the combined area similar to a centreboard and
> > > > > rudder of other boats with the same sail area. With the Harry
> > > > > configuration there should be a tendency to round-up with no
> > > > > rudders until the ww hull unloads but these rudders are not going
> > > > > to have much feel so there may be no indication of weather
> > > helm. So
> > > > > it may require actually observing the angle of trim between the
> > > > > rudders.
> > > > > >
> > > > > > The aim should be to trim the rudders to eliminate leeway.
> > > > > Current aside, the boat should go where it is pointed. So the idea
> > > > > would be to set a course and then slowly trim the rudders relative
> > > > > to each other while maintaining the course to get the best speed.
> > > > > Once this has been done a couple of times the best settings will
> > > > > become intuitive for any particular conditions.
> > > > > >
> > > > > > These rudders will not have a cavitation issue for any
> > > reasonable
> > > > > speed expectation - Cp less than 0.5 in best working region. If
> > > > > thicker section for higher AR then cavitation would need to be
> > > > > checked and the vortex shedding will be more significant.
> > > > > >
> > > > > > The vortex shedding should not be an issue on this section
> > > either
> > > > > as the separation is only on the last 1 to 2%.
> > > > > >
> > > > > > Rick
> > > > > >
> > > > >
> > > > >
> > > >
> > > > Rick Willoughby
> > > > rickwill@
> > > > 03 9796 2415
> > > > 0419 104 821
> > > >
> > >
> > >
> >
> > Rick Willoughby
> > rickwill@
> > 03 9796 2415
> > 0419 104 821
> >
>