dw_asym_pressureDialogue between the trimmer and helmsman is always important but it’s even more critical than with a symmetric spinnaker. The helmsman has to listen to his trimmer, providing information and letting the helmsman decide what to do.

This combination of driving and trimming, and the communication between the two, is the biggest source of gain between boats in most fleets. The angles and pressure are always changing and its too easy to go too deep and the spinnaker collapses, and that’s the sign of a lack of communication. The trimmer should tell the helmsman, “I’m running out of pressure, we’re too deep.” And head up 5 degrees. With pressure you can start going down. A third guy should be calling puffs. The helmsman needs information to decide whether to sail high to go to new pressure, or low to stay in the best pressure. That person needs to look at where the boat will intersect the wind.

Because wind pressure allows you to sail low, it’s more important to get to the pressure than it is to worry about the wind angle. Two extra knots of pressure can give you 15 degrees to work down with, so it can be better to take the lift if it has pressure than it is to gybe into the header and have less wind.

Because of the angles, sailing with over-eased asymmetric sails is slower than having them slightly over-trimmed. With a curl in the luff half the time you’re losing area. Sail with a more “solid” luff than with spinnakers. By keeping the trimming movement down, it’s quicker and easier for the helmsman to drive to the sail. The sail is rigged, and more difficult to change later (but not impossible).