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Old 03-16-2002
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Carol Cronin is on a distinguished road
Synchronized Sail Trim


Coordinating your sail trim during maneuvers is critical for optimum performance, particularly on mark roundings like the one shown above.
I recently spent a day watching the competition at the Thistle Midwinters East from on board a powerboat and I managed to learn quite a bit. While itís always too easy to be critical as a spectator, itís also possible to see where the biggest gains are made around the course. What really stood out for me on that day was that consistently coordinated sail trim through maneuvers (tacks, jibes, and mark roundings in particular) was really what separated those at the front of the fleet from the rest of the group.

What makes perfecting maneuvers like these so difficult is that you have to steer the boat not only with the tiller, but also with the sails and, in some boats, with crew weight. Consider this: if you had an outboard motor on the transom pushing the boat, the steering would be easy. But in a sailboat your source of power also affects your course, so how much you adjust each sail for changes in apparent wind angle also affects your steering. Leeward mark roundings provide the best example for examining what needs to happen here, so letís look at those first.

I've always thought that the leeward mark rounding is the hardest maneuver to perform well, even in the absence of traffic. Doing so requires perfection in sail trim and boat handling from the whole crew because thatís what it takes to maintain speed during the rounding. Now in theory this doesn't seem too hardóyou simply come in wide, away from the mark and sail out tight, close to the mark. Itís just a matter of turning the tiller or the wheel a certain amount and carving a turn, and that's just a matter of practice, right? But the sail trim is really a crucial part of the equation, since sails provide the horsepower to get you around the mark. So how do you steer around the mark and pull the sails in just right?


For sailors who both steer and trim, coordinating sail trim is an even more difficult task. If you can, says the author, hand off the sheet to someone else, at least temporarily.

The first problem to solve is just how to pull in the main while carving that smooth turn around the mark, particularly if youíre on a boat where itís customary for the person steering to also trim the mainsheet. Steering (which involves pushing the tiller away or turning the wheel) and pulling hand over hand on the mainsheet (pulling a line toward you) is kind of like patting your head and rubbing your stomach at the same time. Practice will help a lot to achieve the proper coordination, but some people will always be better at it than others.

One solution is to hand off the mainsheet to another crewmember. Then it becomes a teamwork issue, because the rate of the turn and the rate of the mainsheet trim have to be coordinated. Ideally, the mainsail should come in gradually as the bow comes up to a close-hauled course. In reality, there are so many variables involved (rate and angle of approach, rate of turn, and wind strength, etc.) that the ideal trim rate is often a moving target. Again, only through practice can you perfect this maneuver.

Coordinated trim of the headsail is also crucial to good leeward mark roundings. Because on most boats the jib is smaller than the mainsail, it is easy to trim it in too fast while sailing around the mark. If the jib beats the mainsail to its upwind trim position, that will effectively pull the bow down and fight the boatís turn up to close-hauled. Instead, you should make sure that the jib trimmer is slightly behind the mainsail trimmer (less trimmed and coming in slightly slower), which may result in the headsail actually luffing as you round the mark. Now this in turn makes good mainsail trim even more crucial; if the main is still luffing as you round the mark, then the jib will be too and the boat wonít accelerate at all.


Getting the sail trim right at a windward mark rounding is harder than it might seem. Note how most of these boats leave the headsail trimmed in for much of the turn downwind.

In heavy air, trimming the mainsail for a leeward mark rounding becomes a careful balancing act between over-trimming (which heels the boat too much and makes it slide sideways to leeward) and under-trimming (which means the mainsail is luffing and you lose height). Having the sail controls preset and crew weight hiked out before the mark rounding will help, since the boat will already be set up for the increase in apparent wind speed as you turn the corner.

Windward mark roundings are also harder than you might think to execute well. Again, the sail trim can make or break the rounding. On most boats, the jib can stay sheeted in tight since that will actually help the bow fall off and reduce interference with the spinnaker (if youíre sailing a boat that uses a kite), but the mainsail needs to be eased as quickly as possible without having the boom hit the mark. And on some boats, itís also important to keep the boat flat, or even heeled to windward, to help it turn down wind. This means the crew shouldn't dive to leeward to hoist the spinnaker until the boat has born away to what is almost a downwind angle.

Tacks and jibes are other times when sail trim coordination is very important. In light air, on many boats itís possible to help steer the boat through turns by using crew weight to roll tack and roll jibe the boat without using too much helm, but the coordination of the sail trim is still the crucial component. In tacking, the most common mistake for beginners is to over-steer, which makes the boat turn fast initially, but reduces momentum out of the tack. You can use your wake as a guide to assess how much speed you carry through the maneuver. Looking back, the less wake you see out of a tack, the more momentum you are maintaining.

"New sailors should use their wake as a guide for tacking, the less wake seen the more momentum maintained out of the tack."
On small boats, I like to trim the mainsail in hard as I start to head up into a tack, since that helps steer the boat toward the wind. Once the bow crosses head to wind, I ease the sheet out slightly beyond normal trim, to allow the boat to build speed on the new tack. After we are settled in and back up to speed, I trim the mainsail back in to its normal setting. If itís a larger boat and someone else is trimming the main, they essentially follow the same procedure, taking their cues from the heading of the boat.

Backing the jib or genoa can make or break a tack, and communication between the trimmer and the driver regarding just how much to back it is crucial. The goals are to minimize luffing and pull the bow around just enough so that the boat ends up at the perfect angle on the new tack. There really is no right answer regarding how much to back the jib or genoa; it will depend on the boat, the wind, the waves, and the rate of your turn. Ideally, just an instant of backwinding is enough. I always try to keep the jib filled on one side or the other; if it luffs you probably need to turn the boat a bit faster. If the trimmer can't get it across fast enough, you probably need to slow down your turn. Once the jib is trimmed to the new side, it should be eased slightly to allow the boat to get up to speed on the new tack.


Coordinated sail trim is absolutely critical during pre-start maneuvering. Note how the boats on the left are still luffing their sails to preserve space to leeward.

Coordinated sail trim is also crucial during pre-start maneuvers. When you are trying to maintain a hole to leeward during the final 20 or 30 seconds before the gun, it is important to keep steerageway, which requires the anticipation of losing it. A tight mainsheet and a loose vang will allow you to claw up to windward without too much speed forward; but again, the details depend
on the sailing characteristics of the boat. Regardless of the kind of boat youíre racing, the headsail trimmer should be ready to back that sail if necessary to pull the bow down, but be careful because too much backwinding can quickly erase any space youíve created to leeward.

In almost any maneuver youíll make on the racecourse, sail trim coordination is critical, particularly between the mainsail and the headsail. Take a moment sometime to tie off the tiller and sail along steering the boat with just the sails. Doing this will teach you pretty quickly how these two sails interact on your particular boat. Remember, the right sail trim coordination and the proper communication between the trimmers and the driver, can only be developed through practice, so get out there and try a few maneuvers! You will soon see an improvement in your performance, and ultimately in your race results.



Suggested Reading:

Basic Mainsail Trim for Racers, Part One by Pete Colby

Basic Mainsail Trim for Racers, Part Two by Pete Colby

Headsail Trimming Basics by Rich Bowen


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