The Commandments of Asym Trim
The Commandments of Asym Trim
Guidelines on trimming your asymmetrical chute.
Commandment No. 3: Thou shall never sail a straight line.
Lutz: When you sail an asymmetric spinnaker boat downwind you're not picking one particular angle; you're "serpentining" all the time. For people new to asymmetric spinnaker sailing this is the one tough thing to get right, right away. When you have pressure in the sail, you sail low, and when you lose it you absolutely have to sail high. So you're continually heading up and down, using the information from the trimmer as to how much pressure is in the sail: you may sense it and you may see it, but it's good to have the trimmer verify that for you. If the sail pressure is light and you head down, it collapses, you're screwed, and you have to head up even higher to fill it up again-you're basically just spinning your wheels and not getting anywhere.
Ullman: One of the most important things is developing the feel of how high to sail the boat and when to change modes between high and low. It's a feel you have to develop-there are no set rules. You can get a sense of it by sailing your polar boatspeeds, remembering that as you go faster you can go deeper and deeper to maintain that boatspeed. My rule of thumb is to use the speedo; as long as speeds are increasing you can go deeper. As soon as they level out or go down, turn the boat up and sail higher. You want the speed increases and decreases to be at the slowest rate possible.
Nixon: In the Melges, the angles change quickly with puffs and you have to steer to the pressure. We always keep a slight curl on the spinnaker-a lot of people sail with a foot of curl-but we always keep a smaller, 2-inch curl, which makes the trimmer concentrate much more because it's a finer trim. We don't use a speedo because the speeds are so up and down. In big breeze people new to asymmetric sailing tend to soak a lot, and the good guys will get the boat on a plane and just rip it out to the corner and come smoking back going 5 knots faster. In heavier boats like the J/80s and 105s the angles are more similar-it's more symmetric-spinnaker-based stuff-but in the light sport boats, when it comes to angles, planing is the most important thing. Klingler: One thing people have trouble with in a marginal planing boat (like the J/80) is not knowing when to turn the boat up to pop it onto a plane. In the 80, you go as deep as you can until you go over this 7.5-knot threshold and as soon as you hit that, you turn the boat up 25 degrees, it will pop up on a plane, and then you're planing at 11.5 knots.
Commandment No. 4: Thou shall use your twings only if you must.
Lutz: When you're tightening a twing, you're closing down the leech a bit. There's potentially a use for twings, but a lot of sail designers design the clews of the sails so that the boom ends up working like a tweaker [twing]. People don't think of it this way, but the lower you go, and the more you ease the main, the more it acts like a twing, putting downward pressure on the spinnaker sheet and closing the upper leech instead of letting it open. So, without thinking about it the mainsail is helping the spinnaker fly more efficiently.
Klingler: We're trying to design the sails so that twings are not critical. I use twings on the J/80 only to hold the sheet down so that when the spinnaker is trimmed, it doesn't trim the main at the same time. I use just enough twing to get the sheet under the boom. In other words, I don't like to use the boom as a twing, and I especially don't like to having someone have to hold the boom out in lighter air. Ullman: We don't use twings at all. In fact, we tell our J/105 customers to take them off the boat. The trouble with twings is they don't just pull the sheet down they pull the sheet in, too.
Bouzaid: On most boats, the boom is the twing and the only reason you'd use one as the boat gets bigger is to keep the sheet away from the boom. A twing will always bring the whole bottom of the sail closer to the boat and everything you're doing is trying to get the spinnaker away from the boat. If you can get away without using them you're better off.
Commandment No. 5: Thou shall always have and talk about pressure.
Lutz: I talk a lot about the dialogue between the trimmer and helmsman, and everybody hears me, but doesn't pay attention. But with an asymmetric, it's even more important [than with a symmetric spinnaker]. The helmsman has to listen to what his trimmer is telling him; at the same time, the spinnaker trimmer shouldn't be telling the helmsman how to drive the boat. The trimmer should be providing information and letting the helmsman decide what he or she should do. Instead of saying, "Head up," or "Head down," the trimmer might say, "I have good pressure, you can head down if you want to, it's still good, it's still good. Another important thing to remember is that the velocity and direction are always changing, and with the asymmetric, because the pressure allows you to sail low, it's almost more important to get to the pressure than it is to get to the angle. With an asymmetric, a couple extra knots of pressure gives you 15 degrees to work down with, so sometimes it's better to take the lift if it has pressure than it is to jibe into the header and have less wind.
Ullman: The combination of driving and trimming, and the communication between the two, is the biggest source of separation of boats in most fleets. The angles and pressure are always changing and you see people get real deep and the spinnaker collapses, and that's the sign of a lack of communication. The trimmer should tell the driver, "I'm running out of pressure, we're too deep." And you head up 5 degrees. And as soon as you have pressure you start nursing it down. When I'm driving, I like to hear feedback only about pressure: Phrases like, "Lots of pressure," "Little pressure," "Losing," "Gaining." A third person rotating into this conversation is the guy calling puffs. You need this information to decide whether to sail high to go to new pressure, or deep to stay in the best pressure. That person wants to look at where you'll intersect the wind. If there's good wind, it's looking to weather at 120 degrees or so. If it's light, maybe 90 degrees.
Bouzaid: One important point is that sailing with over-eased asymmetric sails is slower than having them slightly over-trimmed. By sailing around with a fold down the luff half the time you're losing that much of the span of the sail. I prefer to sail with the luff a tad more solid, as we used to with regular spinnakers. Plus, if you're easing it way out, trimming it in, and then over-trimming it, you have a lot of sheet movement. If you keep sheet movement down, it's quicker and easier for the helmsman to drive to the sail. Nixon: On the new designs the clews are higher and the sails are more forgiving, which makes it easier to steer the boat to it. But the dialogue between the trimmer and helmsman is paramount in a boat like the Melges. We're talking the whole time, using the words good, average, bad, or medium to describe the pressure in the sail. With "medium," we're trying to hold the course, in when it's "good" we're trying to burn down a little bit. The dialogue has to be quick.