Hello upchurchmr,
Apparently you are interested in trying an A-frame rig or something similar on your Tornado 20 cat? Daysailing, you say, still high performance, but maybe something safer, easier to handle, more like a cruiser?
If you already have the gear, the beam, etc., for carrying a jib at the center between the bows, probably cheapest and easiest would be an A-frame with just a jib and a mainsail on the centerline, both on furlers, no booms, like the SMG 50 mentioned several times in this thread,
http://www.sail-the-difference.com/..._of_the_easy_to_use_smg_catamaran/smg_50plus/
and Gary Hoyt's Manta Clipper is very similar (see first 2 photos below) although it has a boom on the mainsail.
Or, if you want to play around with a lot of different sail configurations, check out my Catbird Suite at
www.damsl.com
But I would suggest the
PYRAMID RIG
It might LOOK more complicated, but another rig that I've experimented with is what I call the Pyramid Rig. It amounts to 3 windsurfer rigs pinned together at the top to form a 3-legged pyramid. All 3 masts rotate 360 degrees. Wishbone booms maintain sail shape on all points of sail. If you get in trouble, you just let the sheets go, and everything weathercocks. You can leave her sitting on the beach with all sails up, or at a dock or a jetty or tethered behind your big boat.
Construction is easy. 3 aluminum tubes of 1 inch circular section, attached to the boat, on hinges if you like so that the rig can be lowered easily, and a bolt at the top through the 3 tube ends all in a row with the jib tube in the middle between the 2 side mast tubes. Every couple of feet along these tubes there is a plastic bushing-type of bearing made of the same kind of stuff that you make prop shaft stern tubes of. These tubes are inner masts and then there is an outer sleeve for each of them and the outer sleeves are 2-inch luff spar sections that slide on over the plastic bearings. So then you have rotating masts which are very strong and can take a lot of bending from the wishbone booms and still rotate around those plastic bearings. The booms are hinged onto pins on the outer mast sleeves.
See the photos below. That tiny jib was ridiculous and I later got a big jib that filled up the foretriangle between the jib mast and the two side masts. I had the little jib made before deciding to go with 1 jib mast in the center instead of 2 jib masts, 1 to each bow. That would have made a 4-legged pyramid. This little cat was actually built as a powercat meant to be driven by an outboard or two, and so it's narrow in comparison to sailing cats, hence a small jib if it had to swing between 2 masts at the bows.
I don't have photos of the big jib, but it was made of dacron. The plastic sails were on the advice of the sailmaker, because a lot of windsurfers had plastic sails. But that was a mistake and I much prefer cloth sails for a number of reasons, not the least of which is that stupid birds will accidentally collide, beak first of course, with see-through sails. Who wants leaky sails?! And they are a pain in the *** to hoist up the groove of the luff spar and to take down, because they have to be rolled up, not folded at all. Dacron will take a lot of punishment.
If I did this rig again, I think I would go with the 4-legged version on a beamier cat, but shouldn't get too long-winded about that here.
You can imagine the advantages of such a rig. You can make it as tall as you want for performance. Yes, there is of course a weight consideration, although I think it could be built of much smaller and thus lighter sections than what I used. I don't think it would be all that much heavier than the conventional rig on a Tornado. And the weight is balanced by the smaller, or re-directed, heeling moment that you get from slanted sails in such a biplane rig, that is, the 2 side masts form a biplane, one side of which is pushing the windward hull down, and the other side is lifting the leeward hull. And since the sails can rotate, you just let them go when heeling gets critical, and they just weathercock. With the wishbone booms, they don't flog like with a conventional boom.
It's very safe downwind, because you let the sails rotate beyond 90 degrees to the wind, so that they are always taking the wind on the proper leading edges and there is no danger of jibing. And do you have trouble reefing your big conventional main downwind, or getting it down? This rig eliminates all that bother. You just let the sheet go, and the sail weathercocks and there's no shrouds in the way.
Anyhow, have a look at the pics below. Note that in some, I was experimenting by using one of the mainsails as a bigger jib, before I got a big cloth jib, and in that makeshift arrangement, the forward end of the boom, where it is attached to the mast, was not high enough, hence the sail shape is not right. Also, the cloth jib was much bigger, its boom much longer.
Note that when the little cat was tethered behind the big cat, with no wind, all the sails fall toward the center, but when the wind got up, they would just weather cock. So I just detached the sheets and left her with sails up. As I said, the plastic sails were a pain in the *** to get on and off.
I sometimes wish I'd done this rig on Catbird Suite, but it would have been much more expensive than the A-frame, because I would have wanted to do it of carbon fiber. Also, the A-frame leaves lots of room for experimentation.
Note that this pyramid rig is very strong. There is very little compression on those masts. And, unlike the vertical bipole rigs on a few cats, which do not have the masts connected at the top, there is no big complication of strength and rotating gear at the base in the pyramid rig, because there is no big bending load at the base, indeed, the masts can be mounted on simple hinges for lowering. Note, too, that there is no great tension involved either, as in conventional rigs, so no need for chain plates.
There is some bending load on the masts from the wishbone booms. It's amazing how much bending the masts can take when there is very little compression. And when bent, they can still rotate when you tighten the sheets, albeit with a little groaning from the plastic bearings. Of course, when you slack the sheet, the bending load is relieved and the mast rotates without complaining. All in all, there is no danger with these booms. They're over your head and there's nothing else for them to bash. But you can dispense with booms if you want, and just not use the leeward mainsail when reaching. Just like with the A-frame, you can sheet down to the boat.
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