Racing Tactics: Clean Air & Covering

Once the starting gun has fired, getting and keeping clear air becomes of prime importance. Wind in the proximity of a starting line is always chopped up by the other boats, so those that get away from the starting area into clear air first will be able to stretch their lead. If you find yourself boxed in between boats to windward and leeward of you, get out of there! This may mean killing your speed, if necessary, so that you can let the windward boat pass. Then you can tack and cross under its stern.

Clean Air

Clear air is important anywhere on the course, but particularly so near the start. Figure 132 shows the various zones of disturbed air coming from a sailboat. The shadings indicate the intensity of the effect. The darker the area, the more detrimental it is for you to be there.

The distance the disturbed air extends to leeward and astern will depend on the wind conditions. As a general rule, air is disturbed at a greater distance in light air than it is in heavy. You probably will be affected adversely by a boat two to four lengths to windward in heavy air, but it can run up to seven lengths in light air.

The worst area is the blanket zone, where a boat is ahead and upwind of you. Boat B is in boat A's blanket zone in Figure 132. Most of the diagrams I've seen show this zone as a cone flowing straight to leeward of the windward boat's sails, and though this is technically correct, I prefer to show it as a curve. For some reason, possibly having to do with the fact that the apparent wind is further aft at the top of the mast than at the bottom, a curve seems better to depict what actually happens on the boat. This will become apparent if you've ever been on a large cruising boat on a beam reach and have passed a smaller boat to leeward of you. Your bow must be well past his bow before you cause him to straighten up. If you're racing a class boat and are trying to hurt a competitor on a reach, you'll find it insufficient to have your masthead fly pointing at his mast. You will probably have to get well past him, so that your fly points ahead of his bow, before the large lower part of your sail area has any effect on him. Once you do get a boat in your blanket zone, however, he will drop back quickly.

When closehauled, a boat behind or slightly to leeward will be in the backwind zone. Though this is a bad position to be in, it's not as harmful as being blanketed and you won't drop back as fast. Still, the turbulent airflow you are receiving from the other boat's sail is usually sufficient to necessitate a tack to clear your air. Boat C is in A's backwind in Figure 132.

Though not as bad as sailing in the backwind zone, a boat to windward of the backwind zone will probably not be able to pass to windward of the leading boat. The lead boat has what is called a "safe leeward position," and as the wind hits the sails of the lead boat, it is bent aft, causing the windward boat to be sailing in an apparent header.

The wind is more on the bow than it is for the lead boat. In this situation, the boat is affected more by a change of wind direction that it is by turbulence. Boat A has a safe leeward position on boat D in Figure 132. An aggressive sailor will try to slow other boats in a race by keeping all these zones in mind using them properly.

Covering

Because there are many potential winners in a race and you can't slow them all, you should only cover those who might provide a serious threat to your own position. The basic rule in all covering situations is to stay between your competition and the mark.

If you are headed for the windward mark and you tack hard on the wind of a competitor, placing him in your blanket zone, he will be forced to tack away. To cover him, you will have to tack as well. This is called a "close cover," and should be used only when you want a competitor to tack. A loose cover is one where you allow your competitor to have free air so he won't be inclined to tack away.

The close cover is used when a rival is sailing away from the desired side on the course or away from a group of boats you should cover. Here, it is important to force him to tack. In effect, you shepherd him back in the desired direction. A loose cover can be used when the rival boat is on the tack on which you want to remain.

Breaking a close cover depends a great deal on the exact positions of the boats. Let's assume you are sailing bow to bow on port tack with a boat just to weather of you. You are both approaching the layline, the imaginary line which takes you to the mark on the other tack without having to tack again. He has you pinned, and every time you bear off to try and get tacking room, he bears off too.

Luffing

If you have luffing rights, a sharp luff head-to-wind can do wonders. But make sure you ease your jib so that it doesnÕt back you over onto the other tack (particularly important with a genoa). You may very well catch him enough by surprise that he will fail to ease his jib in time. The result will be that he will fall off on the other tack short of the layline. You can now go on until you reach the layline and starboard tack him near the mark when you come together again (assuming marks are rounded to port).

False Tacks

However, a luff may be impossible if you are well to leeward and behind. Here, a series of tacks may just discourage the boat covering especially if the skipper feels they are losing ground to other boats by engaging in this private tacking duel. If the covering skipper is not discouraged, which would be the case if you are the only boat that poses an immediate threat, or if it's a match race series, a "false" tack can sometimes work. This tack is executed exactly like a tack up to the head-to-wind point, but at that point you fall back on the original tack.

Your crew must know that the tack will be a false one, but must make it appear to be authentic by freeing the jib, crossing the boat, and doing whatever else is normally done on the boat during a tack. Hopefully, an overanxious coverer will tack too quickly and, after completing the tack, will have to regain speed in order to tack back again.

A false tack rarely works when the covering boat's crew is looking for it and is prepared to delay their tack until your intentions are obvious. In that case, you had better complete your own tack, because any hesitation when head-to-wind will cause you to lose ground. Theatrical acting, along with a louder than usual "ready about," rarely works either, although some sailors try it.

Mark-Rounding Tactics

If you are still unable to shake clear of the covering boat and you are approaching the layline to leeward and behind the covering boat, your only hope is that they will overstand (go past the layline). If they are so intent on covering you, they may not notice that they are on the layline. The proper thing to do is to keep on going. Don't tack until the covering boat tacks. Pinch your boat to get as far to windward as possible. This will slow you down, and your coverer may become gleeful at how badly he's "hurting" you and how much he's pulling ahead.

Sail Tip #71 - Racing Tactics: Clean Air & Covering

Reprinted from:
Fundamentals of Sailing, Cruising & Racing
By Steve Colgate; Published by
W. W. Norton & Company

About Fundamentals of Sailing, Cruising & Racing by Steve Colgate:
America's most experienced and renowned sailing instructor has put down in this volume all he knows about his subject. And he has done it in a way that reflects years of searching for and finding the best way to teach sailing. The result is an incomparable book for anyone who wants to become an expert sailor.A complete line of books are available in bookstores and online at all key book vendors. Or call 800-221-4326 or email sail@offshore-sailing.com