Beware of overstanding

There are two reasons why get­ting too far to the sides of the course is even more risky on a run than a beat. First, your jibing angle is usually narrower than your tack­ing angle (except in lighter air with asymmetrical chutes). When your jibing angle is only 20° or 30°, for example, it's easy to sail past the layllne to the leeward mark (espe­cially if there's a winclshifi or the mark was not placed perfectly).

Second, if the wind velocity changes at all, your jibing angle will be impacted a lot more than your tacking angle. In light to medi­um air, a small increase of just a knot or two in pressure might change your optimal heading by 10° or more! This is a huge factor that can easily make you go from under­standing to overstanding by a lot!

The consequences of overstand­ing are roughly proportional to the wind velocity. In light air, it's not too bad to overstand a little since sailing higher and faster doesn't hurt your VMG too much. But in heavy air, when you can sail low and fast, reaching to the mark is a killer. Therefore, you should be conservative about layline calls in breeze and possibly willing to take slightly more risk in lighter air.

 
Narrow jibing angle

Unless you are sailing with an asymmetrical chute in light to medium air, your downwind jibing angle is usually a lot narrower than your upwind tacking angle. That makes it more likely that the run will not be square.

All it takes is a leeward mark that is slightly out of position, or a small windshift during the race, and you'll have a skewed leeward leg, especially if it's windy (when your jibing angle is narrowest).

Therefore, when you go around the windward mark, consider the strong possibility that you may be close to fetching the leeward mark.

Laylines affected by pressure

An increase in wind pressure is always good for performance. It allows you to sail higher and faster ' on a beat, and lower and faster on a run. But the effects of a puff are much greater downwind.

When you are running, a small increase in wind can change your sailing angle a lot. This is especially true in light to medium air. In these conditions, a two-knot puff might allow you to bear off ten degrees! This applies to all boats, but it is more pronounced for lighter boats and boats with asymmetrical chutes.

When your sailing angle can change 10 or 20 degrees in puffs, it's easy to overstand the leeward mark. This applies much more to runs than beats.