- September 30th, 2009
- in Yachting
Tricks and Tips for Spinnaker Trim – Students often tell me that one reason they got attracted to the idea of sailing was seeing a fleet of racers pop open their big, colourful sails and appear to just float along the bay. Words like “poetry” and “graceful” sometimes pepper these conversations. Later, when getting to deploy these poetic, graceful spinnakers, students seem to prefer words such as “beast,” “bastard” and other terms not suitable for this family-friendly forum.
Indeed, coming to terms with the spinnaker, whether on a 20-something footer or a 20-something metre boat, a few principles apply. First, whoever coined the phrase “eternal vigilance is the price of liberty,” probably got the idea while trimming a spinnaker, since eternal vigilance is indeed the trimmer's stock-in-trade. Keeping the spinnaker at the appropriate angle to the apparent wind and communicating with the helm take significant amounts of concentration which pays off in terms of boat speed.
One impression many sailors have is that the spinnaker is like a hot-air balloon or an umbrella and will simply catch the wind that is blowing into it. Instead, think of the spinnaker as a foil, like any other sail, that causes the wind to bend and is working most efficiently when the wind is flowing smoothly around the outside (leeward) surface. It's not called a kite for nothing.
The lines that control the spinnaker are the guy which controls the tack by way of the pole on the weather side and the sheet which controls the leeward end of the sail. Since the spinnaker (in this case) is symmetrical, familiar terms such as tack and clew are inter-changeable as the spinnaker is gybed. Clearly, the key to top trim is to have clear communication between the various crew trimming the sheet, the guy and with the helm.
The conventional wisdom is to set the pole perpendicular to the apparent wind—just make sure you are reading the wind from the top of the mast (masthead fly or anemometer-type system) rather than lower down. Make sure, too, that the tack and clew are at the same height—if the tack is lower than the clew, raise the pole to even them out. Ease the sheet until you see the luff begin to curl, and then trim until the curl disappears. Keeping the luff on the edge of curling is the bane of the trimmer's life—the slightest distraction will see the spinnaker collapsing. The idea is to keep the air flowing along the outside of the sail—as the sheet is eased, the wind pressure pushes back against the outside of the luff, creating the curl. Then the trimmer pulls back on the sheet to allow the air to flow smoothly. If the luff doesn't curl every so often, the boat is sailing slow.
As the boat accelerates when surfing a wave, apparent wind moves forward and increases. The spinnaker trimmer needs to trim the sheet immediately, and to ease out as the boat slows again. Inattention can cause a rapid collapse of the sail. The trimmer's reactions can be compromised if the helm tries to compensate by steering the boat away from the luffs—make sure there is good communication, then the helm can help avoid a collapse by falling off as the boat accelerates.
When the luff begins to curl, take note of whether it is curling high up or low down. If the curl is high, the pole is too low, and vice versa. When adjusting the pole height, don't just control the outboard end, but if possible raise or lower the pole along the track which attaches it to the mast.
One important point is to trim the sheet rather than the guy—you want a stable leading edge with the angle of attack being controlled from the clew end, rather than pulling the tack into the wind, or letting it fall away.
In conclusion, the secret to spinnaker trim is to make the adjustments quick and slick. Keeping the movement fluid will help avoid collapse, provided you react immediately to the first signs of a folding luff. Then perhaps you will feel the poetry and grace generated by the powerful beast that you control.