Join Date: Feb 2000
Location: Annapolis, Md
Thanked 164 Times in 133 Posts
Rep Power: 10
Gear/Rig needed for Asym. Spinn?
Some of this depends on the cut of the chute but the current theory is that the pole wants to project approximately 25% outboard than your ''J'' dimension. (Roughly the distance between your mast at the deck and your forestay.) This allows for good balance compromize between carrying the largest chute that you can that will be stabile in flight and which won''t have major interference between the mainsail and chute. As you move the tack of the sail aft toward the mainsail the chute needs to be smaller in area and will be less stabile and effective.
Most of the boats that I have sailed on with Assymetricals have sheets (on each side of the boat) that are twice the length of the boat from the tack point of the chute to the turning block at the transom. The reason being that the sheet needs to start from the tack point that can as far aft as the back of the cabin top when stetched tight for a pre-fed launch. Fron there the sheet runs around the tack point at the bow and back the length of the boat to the turning block and then forward again to the winch typically within a couple feet of the end of the cabin as well. Beyond that you need enough line to wrap the winch a few times and to have some line to hold in your hands as you start the jibe.
Beyond that twings are very important to shaping the sail and keeping it stabile. Twings act on the spinacker sheet similarly to the way that moving a genoa lead block changes genoa shape. The twings consist of a bullet block that rides on the spinsheet. The bail is tied to a control line that is lead through a bullet block at the rail and back to a cleat near the cockpit. As you swing onto a more of a reach the twin is applied to help control the head of the sail.
Now for the bad news, after years of using both types of chutes, I really think that the symmetrical chutes are much easier to fly short handed. While single-handed jibes are harder on symetrical chutes, the assymetrical chutes are a lot less stabile and take a lot more care to prevent really serious wraps, wraps of a type that you really can''t clear single-handed.