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Asymmetricals come in a variety of shapes, sizes and designs. It would be impossible to find a consensus as to what the optimal shape or construction would be. The distinguishing feature of every asymmetrical spinnaker however, is that they have a tack and a clew, like a jib. The tack is fixed to the boat and both sheets, port and starboard are attached to the clew. They can be flown without a conventional pole attached to the mast, so that means no jibes on a steep pitching foredeck with a cumbersome pole. If used with a sock, or snuffer, they can be launched and retrieved in a matter of seconds. For those who sail short handed or with a less athletic crew, these are major advantages.

Sail Types
Asymmetrical sails are often described by a code. They are categorized as:
• Code 0 (Close haul Asymmetrical)
• Code 1A Light Reaching Asymmetrical
• Code 2A Light Running Asymmetrical
• Code 3A All Purpose Reaching Asymmetrical
• Code 4A All Purpose Running Asymmetrical

Flatter asymmetricals are at times referred to as gennakers, being a cross between a genoa and a spinnaker.

The Hoist
Set up is similar to a conventional spinnaker, except that the tack is attached to an adjustable tack line, fed back to the cockpit. This tack line allows adjustment of the tack height and the luff curve. The sheets run down each side of the boat and are attached to the clew.  With the tack and clew cared for, the sail is hoisted on a spinnaker halyard right from the bag.

If the asymmetrical is in a sock, or snuffer, the setup is the same as just described, but the whole sock and sail are hoisted on the spinnaker halyard. Once hoisted, the sock is hoisted and the sock line tied off at the mast. It is best to leave a foot or two of halyard at the top of the sail, so it is not completely hoisted. Otherwise, it is impossible to hoist the sock clear of the head of the sail.

Jibing
Jibing offers some options. The first, if being used with a sock, is to pull the sock down over the still hoisted sail. This is the safest alternative, but sacrifices speed. With the sock in place, it can be passed around the forestay during the jib.

The second is to jibe the asymmetrical the same as any other headsail, but this can be difficult if the tack is not on a bow pole or sprit. The sail must pass through the small space between the luff of the spinnaker and the forestay. If timing is not perfect it can create a mess.

The third option is to jibe the asymmetrical outside of the luff. This requires running the lazy sheet around the outside of the sail before it is hoisted. In this way, the sail passes ahead of the luff during the jib, and the likelihood of a problem is greatly reduced.

Comparison
Asymmetrical spinnakers trim much the same as symmetricals. The luff is kept at the point of just breaking, but maintaining an attached flow. Reaching without a pole, the sail will move aft, becoming less efficient and changing the balance of the helm. To compensate, the tack line is tightened and a strap attached to the tack to strap it to the forestay.

Many sailors prefer asymmetricals for the ease of use – no pole, easier to jibe, easy to douse if used with a sock. Their weakness is on deep angles off the wind. Here they are hard to keep filled in the shadow of the mainsail. A bow pole helps immensely to get the sail forward and out of the mainsail’s shadow, but still it is no match for a deep symmetrical spinnaker on a pole.

For this reason, many racers use a pole with an asymmetrical to hold the tack away from the boat on deep downwind angles. This is essentially getting the best of both worlds, but it means having to use a pole again. In spite of that fact, they still retain all the benefits of an asymmetrical sail. A flatter cut will still reach at much higher angles and more easily than a symmetrical. Even if it is used with a pole, it will be easier to jibe than a symmetrical. Ideally, a boat would have a selection of 3 or 4 downwind sails to match a variety of sailing angles and conditions.

Speak to the Ullman sails rep in your area about the downwind sails that are right for you and your boat. We have the experience and technology to maximize your time on the water, whether cruising or racing. Look for Ullman Sails, “An Investment in Performance”