Hi Mike,
It does seem that just putting Rare Bird's rig on a Harry would give
you good numbers, but I am concerned that might now show the whole
picture.
For one, the main is going to be a very heavy sailcloth and in light
air it seems like it will have trouble setting the proper shape. Much
easier for a sail that is designed for 0-15 kts, instead of one
designed for 10-50 kts.
Less importantly, but it is also going to be quite an effort lifting
that whole 500 sq ft of main for that light air performance. I know
the exercise is good for me, but when I get all sweaty, my wine and
cheeze mood sours <grin>.
Is it possible to design a larger headsail where the center of effort
is far enough aft to keep the COE of the whole rig aft of the mast? I
have not been able to find out how to calculate that. Can somebody on
the list help with that?
If that could be done, with a light fabric, it seems like it would be
a handy solution (other than having to roll it up to complete your
shunt).
- Gardner
On Thu, Apr 23, 2009 at 9:15 AM, Mike Crawford <jmichael@gwi.
>
>
>
> I suppose one central question here is: how many boats are pushing an SA/D
> of 50 or 60 (non-overlapping area) with the screecher in use?
>
> I love to get out on the water and go fast, but I rarely race
> unofficially, and never race officially. I also don't follow the race
> circuits in detail, so it's possible that I'm making assumptions that aren't
> fully-supported.
>
> So, let's look at the well-known Corsair F-31 Cheekee Monkee, which places
> quite well in a lot of mulihull races:
>
>
> http://www.boatersl
>
> Mast height: 45', mainsail: 426 sf, code zero headsail: 736.
>
> Assuming 1/3 of that code zero sail is overlap (could be more), that's a
> total non-overlapping sail area of 916 sf. Assuming the mast step is 6' off
> the water, that's a mast height of 51' off the water. Also assume that the
> 3950 pound racing weight published includes crew, motor, water, batteries,
> and fuel. It might not, but we'll be conservative. Please feel free to
> correct these assumptions.
>
> That gives an SA/D of 59 and a BN of 1,92.
>
> Now take the Harry I'd like to build: 2600 pounds (1900 plus 700 for crew
> and goodies), mast height off the water of 55 feet.
>
> The Harry has an SA/D of 64 and a Bruce Number of 2.0.
>
> Does the Harry now need a screecher? Isn't it already insane?
>
> More important, the Harry will be infinitely easier to sail. I wouldn't
> dream of singlehanding Cheekee Monkee with a code zero out.
>
> Even if you could somehow figure out how to get that headsail across the
> mast by yourself, and not get any sheets or clews caught on rigging, I'm not
> sure you could do that while executing a graceful tack and not getting
> caught in irons, or alternately, coming on too hard in bigger winds. Even
> with a skipper and one or two crew this would require some skill. Winches
> and sail handling on every tack. If the wind picks up to the point where
> the headsail is dangerous, that huge code zero might be asking for two
> people to stow it safely (and without undue flogging).
>
> On the Harry, you might have to put down your cold drink if you're
> shunting, but you might not even need a winch. If you can tack, you might
> not have to do anything but steer (because the wind is so light you're not
> worried about a lower righting moment on the opposite tack). Of, if the
> wind is too low to tack, you just smile and shunt. Or, if the wind gets to
> high, you dump your one sheet, smile, and reef.
>
> No getting caught in irons when it's too light, and with a weathercocking
> rig, no worries about the boat steering back into a power heading if you
> drop the tiller while tending all those strings.
>
> Then there are the other two-dozen harryproa benefits that I've blathered
> on about recently, and won't repeat because the dead horse has already been
> beaten.
>
> In the end, I'm not sure a Harryproa needs a screecher or code zero to
> compete with an out-and-out racer like Cheekee Monkee.
>
> As for that 986 sf spinnaker, though, I'm silent. Dead downwind, while
> racing, CM would probably have the advantage.
>
> - Mike
>
>
>
>
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