WHY do we shorten sail?
A lot of informative answers have already been given in this thread. However, before anyone comes to the conclusion that shortening sail is supposed to be some kind of one-routine-fits-all, knee-jerk-type procedure I would like to suggest a flexible and adaptable response, especially for the more experienced sailor.What do you hope to achieve foremost by shortening sail in a given situation? This question needs to be asked first. In my experience, the five most common reasons to shorten sail are:(1) to reduce excessive heeling [since that reduces comfort, increases anxiety and compromises many aspects of personal safety; while usually accompanied by (2)]; (2) to reduce weather helm [since it fatigues the helmsman, may induce a broach and tends to thwart the use of autopilots and windvanes while straining rudder and steering gear]; (3) to reduce speed [since one might otherwise arrive too early, fatigue an inexperienced helmsman, slam too much, troll the tuna bait too fast or risk high speed collisions, e.g. in poor visibility]; (4) to protect against expected squalls and gusts [e.g. in particularly squally conditions and regions; or simply during the night]; (5) to protect a weakened sail, mast, shroud, stay or rudder.Only after you have made up your mind what it is that you are trying to achieve foremost of all you are ready to determine wether shortening sail is the best response indeed and, if so, which sail(s) should be shortened first. For instance, it might not be such a hot idea to shorten a headsail first if you are only trying to reduce weather helm so the autopilot can do its job better. On the other hand it might not be the best idea to shorten a nicely flattened mainsail with a properly vanged and sheeted boom which allows the leach to spill air at the top while your tired, baggy masthead genoa refuses to be flattened and causes most of the heeling (and thereby weather helm).Besides needing to know what you are trying to achieve by shortening sail, you also have to consider such issues as which point of sail would serve your purpose best, how much drive you can afford to lose before you could no longer punch through heavy seas, or how much pointing ability (and drive) you are going to need to stay off a lee shore or shallow reef area before choosing a new, shortened sail plan.Flying Dutchman"Rivendel II" (Hunter Legend 43, hull #1)