1. Top of the beat: If you’re sharing a racecourse with multiple classes, the slow zone you’re most likely to encounter is the large wind shadow that forms as the fleet ahead sets their kites. The worst of the wind shadow, and the place to avoid most ofen, is the top-left side of the racecourse, especially in light air. When figuring out how best to avoid this wind shadow, consider the angle the other fleet will be sailing on its downwind leg. If it’s a deep angle, you will likely find clear air on the edges of the racecourse. If it’s more of a reach at higher angles, your port layline area will become a slow zone.
In very light air with multiple fleets, the wind and water is so disturbed in the middle of the course that going all the way to, or slightly beyond, the layline can actually be more beneficial than getting stuck in the middle slow zone. If it’s windy, the bad-air is not as severe, so you don’t have to work quite as hard to avoid it.
Another consideration as you approach the top of the racecourse is whether the fleet ahead will jibe-set. This usually happens if there has been a big right shift, and even then, the leaders ofen delay their jibes in order to get away from the wind shadow created by the starboard-tack layline or offset leg. If everyone ahead is jibing as you approach the windward mark, be conscious of the bad air they will create on the right side of your course and consider going all the way to starboard layline to avoid it, or tacking well below the jibing boats coming downwind.
When approaching packs of boats, the main concern is the number of boats and their congestion. A fleet of Melges 32s lined up bow-to-stern with huge spinnakers will create a much larger slow zone than a handful of J/24s that are spread out. Make your tactical decisions based on the severity of the approaching wind shadow.
2. The run: When you’re sailing downwind with other fleets coming upwind toward you, individual boats won’t create too much bad air. Collectively, they can cast a wider slow zone than you may think. In such cases, you should avoid their wind shadow as best you can by passing to their windward side. Usually, the boats coming upwind are spread out so you can view each boat as an individual obstacle and pass it to weather whenever possible. At the same time, keep your eyes peeled and avoid any unnecessary fouls or collisions. Sometimes, upwind leeward and starboard-tack boats sneak up on you if you are not paying attention. And keep in mind that even if you do have the right of way on a boat coming upwind, it’s ofen faster to avoid them rather than create an altercation. It’s easier to maneuver while sailing downwind, so make small course changes and sail fast.
3. The gate: A leeward mark, and especially a leeward gate, can create one sizeable slow zone. As boats compress, a long, wide wind shadow results. Usually, your fleet will cluster into groups and/or mostly occupy one side of the run. When this is the case, the other side of the course has much clearer wind and water. One gate will send you into a bunch of spinnakers and choppy water, while the other will send you into an undisturbed open space. Usually, it pays to head into the open space and then either continue or tack once the downwind traffic has cleared away. You don’t always have to round the upwind gate or the one that sends you the way you want to go. It regularly pays to take the path of least resistance and clear air, and then head in the direction you think is favored.