my original motivation to suggest tacking and gybing was not that shunting is hard, but rather that i think shunting would be slower. correct me if i'm wrong here-- VMG is NEGATIVE during a shunt, no? that's not the case with tacking/gybing, unless you go into irons of course.

my tacking experience with catamarans is that ones that go to weather well rarely get into irons. seems to me then if one designed a proa that optimized windward ability, then getting into irons wouldn't be a problem, and so tacking would be faster than shunting.

moreover, windward ability aligns well with my taste in boating: going downwind is much more pleasant than going upwind. trading downwind performance for upwind performance during the design process means you'll minimize the unpleasant TIME (not distance) spent going upwind on a roundtrip course. plus the safety benefit of getting away from lee shores.

i can see the point about diagonal stability. downwind at least. upwind i think transverse stability is more important. either way though, i'm not advocating tacking/gybing in heavy wind, or in all tactical situations. boat handling in my mind is more important than boat speed on short-legged W/L buoy races (or narrow channels, take your pick). if one flies a hull in 20 kts of wind, then in 10 kts on a W/L course, it's gotta be faster to tack/gybe. in light or heavy winds or ocean-racing where boat speed is more important because you're not changing course that often, then sure, shunt.

i guess without realizing it beforehand i've started the whole tacking outrigger vs. proa debate. so many configurations and tactics for a boat with two hulls. sure would be nice if we all sailed on the same body of water so we could do some two boat testing!

ben

--- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@...> wrote:
>
> We had to sail El upwind and uptide for 300m in a 50m wide channel a
> couple of weeks ago. I would not want to be doing it all day long, but it
> was not too hard. A couple of 10 year olds were doing the sheet and
> steering. Shunting in this situation was safe, as if they stuffed it up
> (happened while trying to avoid a power boat coming in) it was easier to
> correct than getting in irons on a tacker.
>
> Shunting a schooner is not as hard as it appears. The fore sail is sheeted
> on first, which eliminates any tendency to luff up and the air off the
> front sail blows the aft sail almost all the way in. The last little bit
> is very lightly loaded as it is in the disturbed air of the fore sail, much
> like a jib and mainsail configuration. This works well to meet the
> requirement for more sail reaching than upwind, without requiring extras.
>
> Just found and uploaded an old, poorly filmed (the camera was in a cut off
> plastic Coke bottle to make it waterproof) and even more poorly edited
> video of W, a 12m/40' cat I designed and built in NZ 20 odd years ago. It
> has a single rudder and a daggerboard mounted on the single beam. It
> tacked reasonably well (1min 40 secs), given that this was the first sail,
> the main was not cut for the very stiff mast and the jib was sheeted to the
> mast. http://www.youtube.com/watch?v=o6Z97sslgm4.
>
> On the end of it is a TV clip about the windmill cat, 30 years ago.
>