Sailing downwind is often more of a challenge than sailing upwind. Downwind performance requires a little more input from the rest of the team and the spinnaker
trimmer is the primary source of this input. A good spinnaker
trimmer needs to stay on his or her toes, making constant adjustments to the trim in response to the fluctuations in the wind's intensity and angle. This person also needs to communicate effectively so that the driver and the rest of the crew know how to respond to keep the boat performing at its optimum.
Before you start feeling under-qualified, remember that guys like me fit into the role of trimming spinnakers all the time, so you can too. Let's start with the basics. The essential objective for trimming the symmetrical spinnaker (we'll tackle asymmetricals in another article) is to keep the sail filled by positioning it in front of the boat, just ahead or to weather of the wind shadow created by the mainsail. You also want to keep the spinnaker out of the water, but we can discuss that in another article about sets and douses. When sailing downwind with a spinnaker, there are three basic adjustments you'll need to pay attention to in order to trim the sail properly. These are pole height, pole position fore and aft, and sheet tension.
Pole Height When the spinnaker is hoisted, the pole is usually already up and in place. Once the sail is up and the halyard is secured, it is time to fine-tune the controls. Stand back and take a look. Who picked those colors anyway? You need to look beyond the aesthetics of the sail to begin assessing its trim. An initial reference on most boats is the height of the clews—the lower corners of the sail. Generally speaking, you want these to be level. If you're sailing aboard a larger boat, it can be a little more difficult to judge the clew heights, but remember this is just a ball-park reference.
Another gauge I like to use is the orientation of the spinnaker's vertical center seam. I try to make sure that this is parallel to the mast. If the windward clew is higher than the leeward one and the bottom of that seam is rocked to weather, the outboard end of the pole probably needs to be lowered or the inboard end raised. (Remember that you generally want to keep the pole parallel to the water.) If the leeward clew looks higher and the bottom of the seam is rocked to leeward, the outboard end may need to be raised or the inboard end lowered.
|" The important thing about pole height is that it affects the flying attitude of the spinnaker." |
The important thing about pole height is that it affects the flying attitude of the spinnaker. With the pole too low, the luff could be too tight, making the front of the sail too round and the rest of the sail too flat. Having the pole too high will make the spinnaker look like a huge balloon stuck to the front of the boat. It not only looks awkward, it's slow.
Fore and Aft Position There really aren't that many factors that govern the fore and aft position of the pole. Basically, the pole should be perpendicular to the breeze to ensure that the spinnaker presents the most projected sail area to the wind. There are a couple of ways to work on achieving this. As a trimmer, I often check myself by looking up at the masthead wind indicator and using that as a gauge. You can also put telltales on the shrouds, which is a little easier and slightly more accurate. And I'm a big advocate of putting telltales on the pole topping lift, as it's the closest reference to the bulk of the spinnaker. These will give you a good indication of the breeze angle without having to crane your neck. The object is to use these references to help you keep the pole perpendicular to the telltales. If you're on a larger boat and you have a dedicated trimmer on the spinnaker guy, get that person to pay close attention to these references and eventually he or she will be working in concert with you on these adjustments, making them before you even call them.
Sheet Tension Now that we are fairly certain the spinnaker pole is in the correct position, the sheet tension becomes more critical. The basic rule of thumb here is to ease the sheet until the luff of the sail curls, then trim the sheet just enough to stop the curling. This is an ongoing process that should keep you busy throughout the entire downwind leg, but be careful not to let the luff curl too much. Too much curl is slow, and it could cause the sail to collapse, which tends to get you—the trimmer—yelled at.
One common mistake of which most spinnaker trimmers are guilty from time to time is getting complacent—or distracted—and over-sheeting the sail. When this happens, the trimmer is no longer playing the curl and the sail trim isn't optimum. Keep an eye out for this kind of lapse in concentration, particularly in lighter conditions, since it takes concerted effort to stay focused for prolonged periods while trimming the spinnaker. If your concentration is beginning to fade, take a quick look around, get a drink of water, or let someone else trim for a while.
In a big breeze, it's important to realize that the spinnaker trim will require particularly close attention. The trimmer needs to be in constant communication with the driver so that he or she knows when the driver is having trouble and the sail needs to be eased.
One of the most critical aspects of being a competent spinnaker trimmer is communication. Some of the best drivers are able to multi-task efficiently when it comes to knowing what the wind will do behind them and where their competitors are. Professional sailors like Ken Read and Russell Coutts have an impressive ability to take in the total picture that way even while driving. And you'll find that many single-handed racers—like Laser sailors—are also attuned in this way. However, even if a helmsman has these abilities, he or she will still need input from the spinnaker trimmer. Downwind, the spinnaker trimmer is essentially steering the boat because that person provides constant input about pressure on the sail, and the driver should respond accordingly.
Another way to look at this it is that the spinnaker is the throttle downwind, and you need to sail in a way that keeps the throttle at full bore. Hence, if there is too little pressure, the trimmer will call for the boat to head up slightly. If there is plenty of pressure, then the trimmer communicates that and the driver responds by bearing away slightly. A typical series of exchanges between the trimmer and the driver off the wind would go something like this:
Trimmer—"Good pressure right now; no need to go higher."
Driver—"OK, I'm holding course."
The helmsman knows he is sailing as high as necessary to get the boat up to speed because of that input from the trimmer. When the boat has built sufficient speed and there's still sufficient pressure on the sail, the helmsman can bear off.
Driver—"I've got good speed. If you've got pressure I'm going to bear down a few degrees."
Trimmer—"Pressure's good. Go ahead and bear away some."
However, if the boat's heading gets too low and the spinnaker begins to lose pressure, the trimmer needs to let the driver know this.
Trimmer—"Pressure's too light now; head up."
Driver—"OK. Coming up two degrees for pressure."
The next time you get a chance to put up the spinnaker, try working with the driver in this fashion. After you get the hang of using this method to maintain pressure—and thus optimum performance—you'll find yourself faring better on the racecourse.
Sensing the Wind
Because the spinnaker trimmer is usually standing up and is more exposed to the elements, he or she has a better position from which to sense the wind angle and strength. In lighter conditions, the trimmer may be able to detect wind shifts before these are recognized by anyone else on board.
It's well known that sailboat-racing legend Dennis Conner used to get a haircut before important races so that he could better feel the breeze on his neck and react to it accordingly. It stands to reason that if you're facing forward downwind and you feel any breeze on your leeward side, that is likely to be a lift. Remember, downwind you are holding one of the biggest telltales in your hand, the spinnaker sheet.