isen@mtuxo.UUCP (d.isenberg) (08/08/85)
Back to basic airfoil theory -- why does a sailboat sail upwind? Because a low pressure area develops on the leeward side of the sail (or, conversely, a high develops on the windward side). This pressure difference is also the cause of heeling; not only does it drive the boat *forward* it also sucks it *down to leeward*! Now, suppose that you could take that low pressure to leeward and make it suck your boat up and forward instead of down and forward. You would then be developing lift and forward drive instead of heel and forward drive. THIS IS EXACTLY WHAT A FULLY ARTICULATED RIG BUYS YOU. Definition: a fully articulated rig is hinged on deck in such a way that it can pivot freely 360 degrees in the horizontal dimensions and 180 in the vertical. In other words, the mast, boom and sail can pivot freely, attached at one point only, as long as they remain at deck level or above. So, here's how you use it. When the wind starts to blow on a conventional rig, it heels, thus reducing the sail area presented to the wind. When the wind blows on an articulated rig, the sailor reduces the sail area presented to the wind by inclining the rig *to windward*, and the result is lift. On a sailboard, the experience is absolutely thrilling: you are leaning back hanging all your weight on the sail, i.e. taking all your weight off the board, and the board, which suddenly displaces say 50 pounds (instead of the ~200 pounds it had with your full weight on it) why -- thaat board TAKES OFF !!. And there you are flying along over the water with all your weight hung in the air spilling just enough wind to keep a big toe from each foot on the board to steer it. So THAT'S why I say that the fully articulated rig makes heeling obsolete (just like this technology here makes paper obsolete). I have seen one of Dick Newick's big trimarans with a huge hairy universal joint at the bottom of the mast (and big hydraulic cylinders on each of the stays and shrouds for radical adjustments of their length). And I did hear that the first monohull to finish the last OSTAR also had a fully articulated rig of some kind. I believe that the fully articulated rig is the most important sailing breakthrough since the development of the fore 'n' aft rig. Will we see f.a.r.'s in Perth? Maybe after they let multihulls race :-). If you need to be convinced, try board sailing. If you thought sailing a conventional rig was fun . . . . . David Isenberg ihnp4!mtuxo!isen 201-576-6386