Mike has summed it up pretty well.
Dead downwind, the sail acts as a flat plate and drags the boat along. On a broad reach, the sail is pretty much at 90 degrees to the boat. If it is eased further as the wind comes aft, the boat will heel to windward. This was very noticable on the smaller boats, less so on RB. At some point, the force from the sails is too far to windward of straight ahead and the drag only route becomes faster. I am not sure when this point is reached, but doubt it is more than 30 degrees by the lee.
Depending on the boat, rig and crew, it can be quicker to work the apparent wind and gybe downwind, but for cruisers and most racer/cruisers, it is invariably quicker to sail directly downwind. This is complicated by many cats and tris these days having assymetric spinnakers which are easier to handle (bowsprit rather than pole) and faster on a reach than a double luffed spinnaker.
The main boom clearance on the windward side is only an issue when you are caught aback. This is a rare event and gets rarer with practice.
Easiest solution is to rig a preventer to stop it happening, but this can lead to control problems while you try to get back on course, particularly if you have accidentally gybed.
Another solution is to have a fuse in the system so that when the boom hits the cabin (better, just before the boom hits the cabin), the main sail releases from the boom and brushes past or over the cabin. The release could be arranged using a snap shackle with it's tripping line tied off to the lee hull.
The schooner is better as a) the boom is shorter/further from the cabin, b) only one sail is likely to have tripped, so you still have steerage speed and c) the easyrig is unbalanced without the main.
Two part masts are cheap and easy to build if the joining sleeve is external which looks agriculrtural. Internal is pretty, but much harder to build.
rob
Mike,
I love getting those long replies of yours. They are always well thought out and interesting reading.One thing that they also tend to do, is to highlight the unspoken assumptions I am laboring under. But, before we get to those, I have a very basic sail question: How does the airfoil help with downwind (broad reach or more) sailing? Perhaps I am just stuck in the old stayed rig mindset, where the sail really can't be let out past 45 degrees without the sail chafing against the shrouds.With a rotating, unstayed rig, do you just put the boom out at 90 degrees to get lift from a broad reach? Then beyond, up to 135 degrees when running? It would seem that the lift vector would then be on the opposite side of the boat from the boom (i.e. if the boom was out to starboard, the boat (if a monohull) would heel to port). Of course, if the boat really will sail at wind speed, then it seems that the speed of the boat will move the apparent wind forward of the beam most of the time.Rob, is that true on the Rare Bird?Back to my unspoken assumptions. You are correct that I want a boat that I can singlehand and that will perform well in light winds (Chesapeake Bay) and upwind (beating down through the Bahamas). There are a couple other things I also want; large bridgedeck, covered with either a hardtop or bimini. To do this, I either need the boom higher than the hardtop, or shorter than the distance from the lw hull to the bridgedeck.I have a layout that I like for everything other than the rig at the moment. It comes apart and will fit into a container for shipping (although I am not really sure that saves enough over a delivery to make it worth while). In order to make that fit, the lw hull can be no more than 4.5' high. Anyway, this means that if I use an easyrig, with a 2 part mast, the boom needs to be only 7.5 feet long, or 6' in the air (so it doesnt hit the hardtop). I could go with a schooner rig, but the masts would still have to be > 39', which means they need to be 2 part masts, which sounds expensive? (Did I mention that my most important unspoken assumption is that the boat be low cost so that I can actually build it??)Anyway, I am currently at am impasse on this one. I am trying to build a 3D model in google sketchup and then I will post the plans and 3D rendering in the group to get suggestions. At the end of the day, I am pretty sure I am just going to get Rob to do a design of his own, based on my favorite layout. His plans always seem to be better than mine, so it will be worth the money to me.Thanks again for the feedback,- GardnerYork, PA