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Asymmetrical Spinnakers: A2 Light Air Running

AWA 105-155°

AWS 8-18 kts

Mid Girth 100-105% of foot length

Rotates to windward of the forestay as the sheet is eased

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The King 40 CHECKMATE sailing with her A2. Photo by Lindsay Preece.

The A2 is the go-to sail on most boats. Sprit boats never run dead downwind because the asymmetrical spinnaker gets blanketed behind the mainsail if they sail below 155 degrees TWA. For an asymmetric spinnaker flown off of a centerline pole, “running” is when the boat sails with the apparent wind angle greater than 90 degrees until the boat is sailing as deep as 155 degrees AWA. An A2 (light/medium runner) is used in apparent wind speeds of 8-18 knots. To help sail as low as possible, UK Sailmakers designs these sails to be full-sized with a full entry and a high clew so that the middle of the sail will flatten out and rotate to windward of the headstay to get as much of the sail as possible out of the wind shadow of the mainsail.

The heart of faster spinnakers is the construction method. The panel layout UK Sailmakers uses is called Matrix, which is a full radial layout that features narrow panels, each oriented to better align the threads in the cloth with the primary load-paths in the spinnaker. This is the most effective way to reduce distortion and make the strongest sail for its weight.

Each panel is shaped on all four sides in order to create a smooth round sail. For one sail to be so versatile, it needs to hold its shape without distorting. Distortion becomes most obvious when close reaching. Spinnakers made with generic nylon cloth stretch in the middle, causing their leeches to harden or hook; which reduces driving power, creates drag, and increases heeling. The only way to prevent distortion, without using too heavy a fabric, is to use performance nylon spinnaker cloth like those made under the Superkote and Airx names. These materials have the same strength and stretch resistance of one weight heavier standard nylon.

Spinnaker Painting Program

Use this program to create a custom look for your new spinnaker or cruising spinnaker. Click here to go to the Spinnaker Painting Program.

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Notice the fullness of the A2 on this TP52 and in all the pictures below.
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