All I know about sailing downwind with spinn I learned from Alex Shafer, John Casey, Jim Novak and a few other INter 20 experts. Also, in Rick White's book, Catamaran Racing for the 90's (it's time for an updated eddition, I think <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />) there is a whole chapter by Randy Smythe about spinnaker sailing techniques.

Here's what they all say: Put it up on one hull and keep it there. Do what ever you have to do, but keep it going fast on one hull until you get to the point where you might wipe out (stuff the one hull too deep).

The theory is; as you lift a hull, you will go faster, and then the aparant wind moves forward, so you go deeper, and faster, at the same time.

As far as luff tension, it is fully adjustable through both the halyard and tack line. A flatter luff will allow you to point higher, while a tighter luff works better for running deeper.

In light air, you want the spin luff flat to go higher, so you ease the halyard or tack line to get the luff flat, ie. no curl. You can move your weight inboard, keep your boards down, anything to get that hull up, then gently steer deeper as it lifts, but keep the hull up.

In more wind (like last week) you have no problem flying a hull, now not tipping over is the problem, so you are swithcing to de-power mode, which means a tighter luff, just like your mainsail, and you are going to sail deeper so you don't need such a flat entry to the spinn.

As I rounded A mark, I dumped the traveler quite a bit to be able to bear off and set the spinn (without steering the boat). As soon as the spin was up, I pulled the boards up about half way, brought the travler up to about 18" out, and then sheeted the kite in, while headding deep. Then I simply had to head up a bit to fly the hull, and as it came up, bear off enough to ride the fine line of keeping the hull up, but not too high. Kind of a delicate zig zag steering, with the pressure. I eased the downhaul and rotator to get the main right but other than that, never touched the mainsheet. I was sitting as far back as I could, and outboard, feet under the straps, butt cheeks right on the aft beam, to try to keep the nose up. There were a couple times I stuffed the bow deep and had to dump the spin sheet to keep upright, especially as I got closer to the leeward gate where the wind was stronger. There I was on two hulls more than one, to keep upright. And do not go off to a corner when the wind is up, you may not be able to cary the spin back to the gate if you get a big gust. It's better to gybe down the middle of the course (staying in the puffs) so you don't overstand.

I was able to hook into a single puff and ride it quite a ways before I had to gybe back to stay near the middle of the course. After the gybe, I head up again until the hull lifts, then ride the next puff on one hull as long as possible, gybe, repeat.

In bigger winds, when you really might eat it, keep it on two hulls to keep the bows from going too deep. Ease the traveler and keep the spin luff tight, which will de-power it, keep your board up, anything it takes to maintain control.

Swimming is slow.