Hi Mary
-On the chute straight downwind ,--you know this one -
we have to build apparent wind and attached flow across the sails,- sailing at some angle to use sails effeciently and creat lift . An airplane would never get off the ground if it placed its wings at a right angle to the wind . A boats sails are propelled by this same lift effect though set verticle.
A stalled sail blocking wind with huge turbulence behind would be limited to below whatever wind speed was present .
Ice boats and landyachts demonstrate this need for attached flow and building apparent wind best with their tremendous speeds well beyond wind speed having little drag except wheels or blades on ice .We have to go through water --or up on it to reduce drag .
2nd part --planning cat hulls will work when heeled but need to be designed accordingly . A conceptual stumbling block for many catsailors that fastiduisly allign hulls bow and stern thinking they go through the water symetrically ,--they never do unless they are perfectly level for and aft , and are not heeled but sailed perfectly level ,-in no waves ,--
When does this occur ? --
Now add angled hulls in the design mix ,-the for and aft sailing attitude dramatically changes hull symetry through the water ,-it is one reason we are seeing more forward bouyancy in hull design by some ,-to reduce bow down tendancies of narrow bow design ,-this has a drag increase trade off ,-but does help lead us to a planning type cat hull shape .
Key is setting hulls at enough angle to work ,-with less heel with both hulls in the water they would work off each other -most likely with a small amount of toe in allignment -
We have seen this with some C Class cat design with angled hulls .-They did this seeking more hull symetry through the water when heeled at a predicted or targeted average wind speed they expected to race in .
3 D computer simulation is really helping to understand effects and clearly seeing the underwater profile of hulls through water with different for and aft and side amounts of heel .
Many catsailors that are very visual thinkers and can potentially see this .
The aft set raked mast ,-longer spin pole and luff angle of spin to help creat lift ,-combined with forward spin lifting foils - to balance the chute and provide lift -per cirrus design features ,-flat angled forward hull sections ,-larger through hull type dagger rudders for adjustment balance and control ,-
light const. -proper rig and sailplan design ,--all these features would make a spectacular cat design .
To sail em we would see crash helmits ,-and begin to see pads worn maybe in combination with P F D , AND SOME SAFE WAY to keep us attached and in control of the boat at those high speeds bouncing over wavetops .
-fun stuff
thanks for all your great posts
and Catsailor Mary
congrates on another great event over the weekend -
Carl
