Bill -

I just realized that you must be the designer of the original Supercat boats. Thanks VERY MUCH for your thoughts !!!

The running backstays sound like a good idea. I wish I had put them on the Viper before I broke the mast. It was 20 knots downwind with the spinnaker when it broke, and we were easing the mainsail for control. Probably lost too much leech tension.

The Viper 640 is actually a fairly heavy boat. It is 725 lbs total, with a 185 lb bulb of lead at the bottom of the foil.

I'm actually worried if the ARC-21 rig is large enough. The original Viper mast was 28' vs the ARC-21's 33'. Sail area is 252 sq-ft vs 282 sq-ft on the ARC-21.

But the ARC-22's 38' mast and 380 sq-ft sailplan is probably way too big. So I thought I'd try the ARC-21 rig with a monster masthead spinnaker, and an 18 footer skiff style long spinnaker pole.

Thanks again ...
Jeff