Found the picture, thanks.
My dual counter rotating rudders sailing.
http://www.youtube.com/user/tsstproa#p/u/3/qtJpm7DCxHA
linked dual counter rotating rudders gives you a positive feel in the helm. the boat steers and stay on course, where every you point the bow it will go with no fuss. Unlike single aft rudder down or even fixed front board down and steering with aft, For get about steering with front only it just gets over poweered. There's a big lag steering with aft board lag heading up into the wind to start the shunt and then again a lag before board regains flow in opposite direction while shunting. This is what gets MOST into trohble during shunts. With dual boards down and counter rotating there is no lag between shunts the boat will pivot as fast or as slow as you want to directly into the wind and come out of a shunt just as fast always maintaining a positive feel no lose of steering what so every in many various conditions I have tested so far.
Here's a clip of me sailing with dual boards disconnected steering felt really mushy very little feel . Proa either wanted to round up many false shunts or when speed was built up enough for rear board to bit windward work wasn't great. Even with this set up locking front borad down after each shunt was one extra tasked do to besides sailing the proa.
http://www.youtube.com/watch?v=oJcY4-gy2BE
I'm really surpise more havn't tried a similar setup with linked counter rotating rudders...
I think its exactly what most proa nuts are looking for...Positive control and the ability to shunt from just about any point of sail. no fear of ever getting cought aback.
I don't buy the dual board going to windward will be slower. I bet the duel boards will going higher to windward in a broader range true wind strengths. Which is faster of the long hual.
My system is crude sure, my sail not at all the greatest but functionality of the set up is flawless.
Todd
--- In harryproa@yahoogroups.com.au, "Herb" <squirebug@...> wrote:
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> Dear All,
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> I have uploaded some of the pictures I took last Sat. to Sangduennoi 20111015. More will follow later as it is taking a very long time to upload the photos 1 by 1. Yahoo will not let me upload them in batch. Any advice on sail shape will be very welcome.
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> Last Sat. our best shunt was at least 150 degrees by GPS - most were close to 180. At this point the boat is unusable because we can't sail close enough to the wind to leave the marina. The wind was blowing into the marina and all we could do was reach back and forth in front of it. All progress to windward was by outboard.
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> It is not just me. Gua (who did all the work on the boat and is a good seaman) can't do any better.
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> Any help will be most welcome!
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> Best regards
> Herb
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> --- In harryproa@yahoogroups.com.au, "tsstproa" <bitme1234@> wrote:
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> > Its sounds like you have enough sail area up to be powered were you?
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> > Why not try two bidirectional boards down all the time connected and counter rotating to a max angle of 30 degrees bidirectional symetrical foils for to aft. You get very precise handling and can crawl to windward if you wanted to.
> >
> > High buoyant low draft proa with only a single steering board you'll need at least a 1 1/2' wide x 5- 6'deep steer board. For helm balance in a greater range of condition. Key note here is that I said "greater range of conditions" .
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> > Todd
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> > --- In harryproa@yahoogroups.com.au, "Herb" <squirebug@> wrote:
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> > > Hi Todd,
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> > > Sangduennoi has 2 rudders, but they lift instead of rotating, so only 1 can be in the water at a time. It is located a little aft of the end of the main boom.
> > >
> > > I think the original sail area was designed to be about 20m^2, but the mast broke last year and was shortened so now both main and jib are at the first reef. I would guess the total area now is about 14 m^2. Rob or Doug do you know for sure?
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> > > The shape of the jib is poor both because of the sag and because we rolled it around a plastic pipe to organize it, but I think it is affecting the shape and now it has to be pushed across during the shunt instead of crossing on it's own.
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> > > Hope to have useful pictures up next week.
> > >
> > > Best regards
> > > Herb
> > >
> > > --- In harryproa@yahoogroups.com.au, "tsstproa" <bitme1234@> wrote:
> > > >
> > > > How many boards where down 1 or two? What size sail area was up?
> > > >
> > > > Todd
> > > >
> > > > --- In harryproa@yahoogroups.com.au, "Herb" <squirebug@> wrote:
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> > > > > Dear All,
> > > > >
> > > > > Sangduennoi (nee Sidecar) entered Thai water for the second time last Sat (8 Oct.)
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> > > > > Only concern at this point is that we couldn't go to windward at all well. I estimate our best shut was about 120 degrees. This wasn't by compass or GPS, but there are several islands and headlands that make estimating angles pretty easy in the Ocean Marina area (Sattahip near Pattaya - about 12N 100E). Any suggestions on how to improve windward performance?
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> > > > > Don't have any pictures yet as I accidentally deleted them from the phone.
> > > > >
> > > > > Best regards
> > > > > Herb
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