An asymmetrical spinnaker or aspin, is a recently[when?] developed sail used when sailing downwind; it can be described as a cross between a genoa and a spinnaker. It is asymmetric like a genoa, but, the asymmetrical spinnaker is not attached to the forestay over the full length of its luff, being rigged like a spinnaker. The asymmetrical spinnaker has a larger camber than a genoa, making it optimal for generating lift at larger angles of attack, but the camber is significantly less than that of a spinnaker.
The asymmetrical spinnaker is a specialty sail primarily used on racing boats, bridging the performance gap between a genoa, which develops maximum driving force when the apparent wind angle is between 35 and 60 degrees, and a spinnaker, which has maximum power when the apparent wind is between 100 and 140 degrees. Due to its geometry, the sail is less prone to collapsing than a spinnaker and does not require the use of spinnaker pole.
Rigging is different from other spinnakers. Maximizing performance and effective sailing of asymmetrical spinnakers requires unique sail and boat trim. It is often paired with a Spinnaker chute.
- Flynn, David (2010). "Just The Facts... A Guide to Asymmetrical Spinnakers" (PDF). Quantum Atlantic (Quantum Sail Design Group, LLC.). Retrieved November 6, 2013.
- Goodall, Sandy. "Inside the Asymmetrical Spinnaker". FX Sails. Retrieved November 8, 2013.
- "Product Brochure, Melges 17" (PDF). Melges Boatworks. Retrieved November 6, 2013.
- Goodall, Sandy. "Rigging Your Asymmetrical Spinnaker". FX Sails. Retrieved November 6, 2013.
- The Editors (June 14, 2005). "The Commandments of Asym Trim". Sailing World. Retrieved November 7, 2013.
- Hancock, Brian. "Using the Asymmetrical Spinnaker". SailNet. Retrieved November 8, 2013.
- "Spinnaker controls". West Marine. Retrieved November 6, 2013.