Your strategic planning for the downwind legs should begin long before you get to the first mark. During your pre-start preparation, review all the downwind legs. What will be the compass course and angle of sail on each? What sails will you probably use? What wind shifts, wave effects or current conditions do you expect?
Before your warning gun, do everything possible to prepare for going downwind. Pack the spinnaker, attach the sheets and halyard, set the topping lift height for the wind velocity and so on. Your object is to minimize the number of distractions you will have on the beat.
As you approach the windward mark, have a crewmember look for the next mark. Then review your strategic plan for the upcoming leg. If you have any new information on the wind, current, etc., don't be afraid to update your strategy. The important thing is to have a good working plan that is useful as a guide.
General Principles for Runs
From a strategic point of view, runs are a lot like beats. Whether you are tacking toward a windward mark or jibing toward a leeward mark, you should follow very similar principles:
Maximize VMG: The first element of your strategy should be to make sure you are sailing downwind as quickly as possible. The fastest angle of sail will be a function of windspeed. In almost all conditions, it's better to sail on a broad reach than a run.
The implication of this is that the fastest way to get to a leeward mark is to "tack downwind." In heavy air, you may be able to sail very close to the rhumbline. In light air, however, or in boats like catamarans or planing dinghies, your jibing angle will be very wide, and you want to sail a much longer course than the rhumbline.
Sail the longer jibe: When sailing beats, the basic rule of thumb is to sail the longer tack. On runs, you should generally stick to the longer jibe. On almost all runs, one jibe is longer than the other. Even if a run is perfectly square, as soon as you sail away from the rhumbline, one jibe will be longer for you.
There are several reasons to sail the longer jibe. First, it maximizes your velocity made good toward the next mark. Second, it keeps you away from laylines as long as possible (see below). And third, it puts you in the best position to take advantage of future windshifts.
How do you know which jibe is longer? There is one fail-safe guide: stay on the jibe where your bow is pointed closer to the mark. This is easy when you're already on the run, but what can you do if you're approaching the windward mark and you want to know whether you should do a bearaway set or a jibe set?
One easy rule of thumb goes as follows: If you sailed longer on starboard tack during the beat, start the run on port tack. For better accuracy, figure out the true wind direction from your instruments, or by averaging port and starboard tack readings. Then compare this to the compass course of the run (the reciprocal of the beat) to choose the longer jibe.
Avoid the laylines and corners: The laylines and corners are no better places to be on a run than they are on a beat. Once you get to a layline, you lose any chance of taking advantage of windshifts. If the wind shifts at all, or if it increases in velocity and changes your jibing angle, you will lose to most other boats. So stay in the middle of the course as much as possible.
Playing Windshifts
The similarities between beats and runs become very evident when you consider windshift strategy. One of the big differences between upwind and downwind strategy is that jibing is less costly than tacking. This means you can react to even smaller wind changes when running, which makes strategy more interesting.
One thing to realize is that shift detection is usually more difficult off the wind, due to several factors. First, the downwind groove is much less defined than the upwind groove, so you won't automatically see shifts in your sails. Second, when sailing downwind, it is more difficult to watch the wind coming on the water (because this is behind you). And third, the interrelationship between apparent wind angle, boatspeed and the angle of the true wind make shift detection difficult downwind. For instance, if you have to bear off to maintain speed, it could be the result of a header or simply an increase in wind velocity.
Because of all these factors, you have to pay special attention to the wind when you are running. Be sure to maintain a constant dialogue between the chute trimmer, helmsman and tactician to monitor shifts and gusts.
Puffs and lulls: Your object on the run is to stay in the areas of most wind velocity. With better velocity, you will be able to sail faster and lower -- an unbeatable combination. Often the biggest gains and losses downwind are due to differences in wind speed across the course. Therefore, you should try to avoid lulls and sail for puffs.
Keeping track of wind velocity is more difficult on runs than beats, largely because you are going with the breeze, so the apparent wind you feel is quite light. It's especially important, therefore, to watch the water (in the direction of your apparent wind) to see what kind of velocity you will be getting. If you see yourself sailing out of a puff, for example, jibe back into it. In general, you should sail high in the lulls (to maintain speed and get to the next puff sooner) and low in the puffs (to carry your speed toward the mark and stay in the puff longer).
Oscillating shifts: When you're sailing upwind in a shifty breeze, you should tack on the headers so you sail on the lifted tack; downwind you should jibe on the lifts so you stay on the headed tack. The reason for this is simple. On a run you want to maintain speed and head as close to the mark as possible; you can best accomplish both goals by sailing on headers.
You want to get on the headed tack as soon as you begin the run. If the last shift on the beat is a starboard lift, then you should do a jibe-set so you are on the port header. Conversely, if you come into the mark on a port lift, then do a bear-away set so you stay on the starboard header. This strategy of sailing away from the next shift is a little different than upwind, where you always want to sail toward the next shift.
Once you are "in phase" with the shifts, you should jibe when you get a lift. You'll recognize a lift because the spinnaker trimmer will have to square the pole and/or the helmsperson will have to head up to maintain speed.
Persistent shifts: When you have a steadily shifting breeze, your downwind strategy is basically opposite what you'd do upwind. On a run, you want to make your first jibe away from the expected shift. This will bring you out ahead of the boats that sail toward the shift. Be sure you jibe short of the layline, however, so you won't overstand as the wind continues to shift.
The only time when you should consider sailing toward a persistent shift is when you expect a significant increase in velocity. If you sail toward this new wind, you will get the velocity first, and this may more than offset any potential losses due to the persistent shift.
Velocity shifts: Velocity shifts on a run are very similar to velocity shifts on a beat; a lull will appear like a header and a puff looks like a lift. While you never want to treat a velocity shift like a "real" shift, at least the consequences of being fooled by a velocity shift are not as severe on a run. There are two reasons for this: 1) jibing is not as costly and 2) if you get fooled into jibing, at least you will be in a puff.
Current
We will get more into current in a later chapter. You should just be aware that current may play a large part in any strategy, upwind or downwind. On a run, you want to sail where the current is strongest with you or weakest against you. Remember that current changes your laylines to the leeward mark, and a favorable current will bring you into the leeward mark rounding much sooner than you think.
Reaches
Reaches are quite different from runs or beats, and they require their own particular strategy. You might think it's relatively simple to reach from one mark to the next, but reaches are actually filled with subtleties that make any leg an exciting challenge.
Go fast: Reaches aren't generally known for big gains and losses. When planing or surfing conditions exist, however, there is potential for large variations in boatspeed. The key here is to get going and settled into a groove as soon as possible. When it's blowing 20, don't worry about easing the cunningham and outhaul when you come around the windward mark. Just set the chute and get your weight out and aft. You can worry about less important details later, when you get a lull.
Rhumbline: The shortest (and usually the fastest) course between any two marks is a straight line, known as the rhumbline. Whenever possible, stick close to the rhumbline so you won't sail extra distance. There are certain times, however, when the fastest route to the next mark is not a straight line:
Building and dying breezes: In a gradually building or dying breeze, sail on the faster heading for the slower part of the reach and on the slower heading for the faster part of the reach. In a building breeze, sail high at the beginning while you have relatively light air and bear off with greater velocity toward the end of the leg. In a dying breeze, get low early and come up fast at the end.
Persistent shift: You should treat persistent shifts a lot like building or dying breezes. In a persistent header, go high first and low later. In a persistent lift, go low first and then higher as you approach the jibe mark.
Puffy wind: When you have puffs and lulls, the ideal reaching course will look like a snake. You should head up in the lulls to maintain your speed, and bear off with speed in the puffs so you don't head high of the mark. These strategies have additional benefits as well. By bearing off in the puffs, you stay with them longer; heading up in the lulls gets you to the next puff sooner.
Oscillating shifts: The snake course also works well for oscillating breezes. When the wind is shifting, try to maintain a consistent apparent wind angle by heading up in the lifts and off in the headers.
Tight reach: If the reach is very tight and it becomes difficult to hold your chute on the rhumbline, bear off until it's easier to fly the chute. In situations like this, the general rule of thumb is to "go fast first." Sail fast with your chute under control and, if necessary, you can always drop the chute later in the leg and head up to a fast jib-reaching angle.