img11011The spinnaker is a restless sail; it takes concentration and a lot of practice to become proficient at trimming it. Following certain principles will help you get there in no time.
When running (as opposed to reaching), the spinnaker is fairly well stalled; it is dragging the boat downwind. True, there's a little flow around the back side of the luff (from a crew member's vantage point), but that doesn't result in much drive. Therefore, we want the greatest projected area possible. The more area exposed to the wind, the greater the sail's effectiveness. Keeping the pole well squared (i.e., aft) and the sheet well trimmed does it. The dotted line spinnaker in the graphic at right (click to enlarge) shows the amount of area exposed to the wind with the pole forward; the solid line spinnaker shows the increased "projected area" from having the pole squared aft.

But there's a price to pay for having the pole well aft. As we square the pole aft, and also trim the sheet to keep the spinnaker from collapsing, it is drawn in closer and closer to the mainsail. Here the spinnaker is in the bad air of the main and loses efficiency, so we must ease the pole forward and ease the sheet to get the chute away from the sail plan. Somewhere there is a happy medium between starving the spinnaker behind the main and losing projected area through too much ease. This is where experience comes in.
The second general principle of spinnaker trimming to remember is that a spinnaker is a symmetrical sail and should look symmetrical when flying. Although there are a few exceptions to this, such as when close reaching or in light air, it is generally true. If the spinnaker is misshapen because the pole is too high or too low, it will lose much of its effectiveness.

Thus, the pole position is important. A good starting point is to set the pole square to the apparent wind. The masthead fly is in undisturbed air and is a good guide. Set the pole at right angles to it. As the boat sails farther downwind, however, air over the main sail tends to flow forward and around the mast, so that the spinnaker is almost sailing by the lee. This means that the pole needs to be squared aft, past perpendicular to the masthead fly. Actually, it will be perpendicular to the shroud telltales. I would use the masthead fly as a guide until the wind is well aft and then switch to shroud tell tales.
There are some unusual instances where the masthead fly is not very accurate for spinnaker trimming, such as on a 12Meter yacht. Because of a Twelve's 3/4 rig, the head of the spinnaker is considerably lower than the masthead fly and the apparent wind at the top of the mast is noticeably farther aft than that at pole height, due to increased wind velocity aloft. Another exception to setting the pole perpendicular to the apparent wind occurs when you are using a very short-footed spinnaker. In that case, squaring the pole brings the clew near the jibstay and much of the projected area is lost.

Generally, the pole should be level, not parallel to the water but perpendicular to the mast. This means that if you raise or lower the outboard end of the pole, you should raise or lower the inboard end (the end attached to the mast) correspondingly. The idea is to get the spinnaker as far away from the sail plan as possible; but to insist on keeping the pole level to achieve this is overkill. A pole has to be cocked 25 degrees from level to decrease its effective length 10 percent, and during the first 20 degrees, only 5 percent is lost, so a few degrees off of level really doesn't make much difference. Probably more speed is lost by fussing around with the inboard pole height than is gained by having the pole exactly level. Also, a slight cock upward will put the pole in line with the guy and reduce the bending strain on the pole.

More importantly is the height at which the whole pole is set. The general rule is to keep the tack and clew of the spinnaker level with the plane of the deck (not the water). But this really goes back to keeping the spinnaker symmetrical. When the two corners are level, the spinnaker is symmetrical, looks good, and sets well.

The exceptions to this occur mainly while reaching, and in either high or low wind velocities. While reaching, particularly when flying the spinnaker with the jib set, the tack of a normal reaching spinnaker on a class boat can be set higher than the clew. This opens the slot between the spinnaker and the jib. It also eases the luff of the spinnaker and flattens the chute.

Once the pole is set correctly, it's fairly simple to play the spinnaker. The sheet should be eased until there is a slight curl along the luff, and then trimmed to make the curl disappear. This must be done constantly and is where concentration plays its biggest part. The novice often overtimes the spinnaker, which then is in the disturbed air behind the mainsail where it collapses. To correct it the novice trims harder, which makes matters worse. This is called a "starve." Pull the pole aft to correct the problem and ease the sheet... "When in doubt, let it out."

The spinnaker guy should also be played, particularly if the boat is small or if you are running in a slop. As the boat rolls to windward, the pole must be squared and the sheet eased. As it rolls to leeward, the pole should be eased forward and the sheet trimmed.
All changes in apparent wind direction necessitate changes in pole position and sheet trim. If the boat starts surfing, falls off a plane, or if the wind velocity changes, the apparent wind direction will be affected and the spinnaker trimmer will have to make adjustments. Moreover, he must learn to anticipate these changes ahead of time.
Easing the halyard. There are times when the spinnaker halyard should be eased. You'll need to know when and how much.

The next time you are on a reach with the spinnaker set, look up behind the mainsail on the lee side. Then ease the spinnaker halyard six inches or so while looking at the leech of the sail, not the head. It will become obvious how much the slot between the spinnaker and the main will open up to allow free air passage.

When running downwind in a breeze, easing the halyard has two effects. First, it gets the spinnaker away from the disturbed air of the mainsail; second, it allows the spinnaker to be more vertical than it is when fully hoisted. In light air, however, the halyard should not be eased because the spinnaker would just come straight down. Nor should it be eased on a reach in heavy air, because the sail's center of effort will go out farther over the water and possibly cause a broach. On a run in heavy air, an eased spinnaker will be more apt to roll from one side of the boat to the other (oscillate) than it would if fully hoisted. In short, easing the halyard is rarely done on a run and is really only beneficial on a medium-air reach, where it can be strikingly effective.

Spinnaker trimming in light air takes a great deal of patience. Lower the pole way down, but always keep the pole end a little higher than the clew. Then, when a puff fills the sail, the pole will be at the proper height. In other words, keep the pole at the proper height for the 10 percent of the time that the spinnaker is filled and doing the boat some good, not the 90 percent of the time that it is drooping and not producing any drive. Another reason to keep the pole a little higher than the clew in light air is that a low pole will stretch the luff and fold it over. When a puff comes, the spinnaker is unable to fill because of the shape of the luff.

The same thing can happen with some very full-shouldered running spinnakers. The luff can collapse from a starve and though you know you must pull the pole aft, first you have to overtrim the sheet to unfold the luff. Only then can you pull the pole back with the spinnaker full. In light air it is better to have the pole too low rather than to high. When the pole is too high, it causes the spinnaker to droop to leeward, to be partially blanketed by the main, and it will take a much stronger puff to fill it.

Another problem occurs in light air when also carrying a jib. On a reach, air flowing past the lee side of the jib causes suction on a reach, and if the spinnaker collapses, it sucks into the jib and is very difficult to fill again. The natural tendency is to trim the jib to get it away from the spinnaker, but actually the opposite should be done. The first time the spinnaker collapses, free the jib sheet to break down the air flow over the jib. If it happens often, take the jib down.

An alternative to taking it down on a small keelboat is to roll it up, if your boat is not fitted with a roller-furling jib. Take a short piece of line, a length of wool, or a piece of single-strand electrical conductor wire with you to the foredeck. Grab the jib slightly aft of midway between the luff and leech and roll it forward, pulling down as you roll. Tie the sail to the jibstay with the line or wool or twist-tie the wire. The beauty of the wool or the twist tie is that you don't have to go back on the foredeck when you want to unroll the jib. Just pull on the jib sheet to break the wool or pop the wire.

Reprinted from "Steve Colgate on Sailing."
By Steve Colgate, Published by W.W. Norton & Co.

Steve Colgate is the founder of Colgate Sailing Schools, with locations in Tortola BVI, Captiva Island FL, Duck Key FL, St. Petersburg FL, Chelsea Piers NY, Liberty Landing NJU and Newport RI.

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