You may have noticed lately in sailing that a lot more people have asymmetric spinnakers than in the past. For years some day sailors and cruisers had them because they did not need a pole and it helped with light air reaching. Not much research went into them because most racing rules outlawed them by limiting the leech lengths of spinnakers or by not allowing one edge to be longer than the other.
This all changed when the Australian 18’ skiffs and International 14’s opened up their rules to allow asymmetric spinnakers. The results were instant and greatly improved. These light weight skiffs went close to double the speeds previously reached. Years later the J80 and Melges 24 were born and then a long line of sport boats all with asymmetric spinnakers.
Still it was not until the late 90’s when heavier keel boats started getting into asymmetric spinnakers. With a little rigging work it came possible to fly an asymmetric off a standard pole. This allowed boats that did not plane to square the pole back and sail deeper.
Asymmetric spinnakers are much more efficient making them always faster while sailing. The only time they are slower is while jibing since the sail has to collapse to complete the jibe. On asymmetric spinnakers the luff is always the luff and the leech is always the leech so it allows us as sailmakers to design the optimum entry and luff curve and the optimum leech exit. On symmetrical spinnakers the leeches and luff have to switch between each other. To make this work there has to be a compromise on what is optimal. It is similar to what it would be like to have a genoa use the leech for the luff on one tack. This would require a major shape change and would never be as fast.
It is a misconception that asymmetric spinnakers can not sail as low as symmetrical spinnakers. When put on a pole and squared back they can sail every bit as low and do so more efficiently. This efficiency turns into speed on the race course.
In the recent Transpac there was only 2 or 3 boats out of the entire fleet that used symmetrical spinnakers. This is becoming common place in long distance racing as well as around the buoys.
For the cruiser and day sailor there has been a big benefit in the research and development in that the sails are easier to trim and use than ever before. They are more efficient and this makes sailing easier and more enjoyable as well as widening the wind range that the sail can be used. The down wind oscillations that use to rock the boats in the bigger wind have almost gone away with the use of asymmetric spinnakers as well. For more information on asymmetric spinnakers contact us at SailsInfo@UllmanSailsSanDiego.com