Last week there were some questions from George B (Alameda, Ca) and I’ve been thinking of how to answer them. With many of the questions here on the sail trim forum I want to “stand back from the question and look at the big picture”. I’ll explain what I mean by that shortly. In most of the seminars I’ve conducted, folks always ask some questions before the class. Many times I tell them to hold the question because when we finish the 3 hour session they will know the answer to what they are asking. Sail trim is easy. Many years ago I did not think that way. I thought sail trim was the most confusing stuff I ever tried to learn. It is easy when presented in an orderly and logical manner. I can take any beginner and within 3 hours in a class and 3 hours on the water practicing the techniques make them into a high intermediate. George asked “in very light air I move the traveler up to the centerline. Will I gain power by applying the vang?”. This question involves 2 elements – ANGLE OF ATTACK and TWIST. By moving the traveler up you are applying power and by applying the vang you are reducing twist in the top of the sail so power does not spill out. Additionally, if you had a rigid vang you would set the boom about 10 degrees above horizontal. George also asked “at what point will the main become too flat ?”. This question involves DRAFT DEPTH. You can never totally flatten the sail but you want it as flat as possible because in light winds the air does not have enough power to get around the sail. How many times have you seen sailors belly out their main in light air and not go anywhere? The reason they don’t move is the wind can’t get around the sail. Another question was “in 10 to 15 knots I control twist by constant mainsheet tension and moving the traveler up and down?”. This question involves TWIST and ANGLE OF ATTACK. The traveler has nothing to do with twist. The travelers only function is to control angle of attack. The mainsheet is the secondary control for twist. The first is the boom vang. The problem with many of the question received on the sail trim forum is they are very specific but only apply to one wind speed and point of sail. Space does not permit me to answer the questions completely and I feel I am short changing the sailor. In other words, I want to “stand back from the question and answer the big picture”. Here’s the problem – there are 8 primary controls for the mainsail and 6 primary controls for the jib. These controls are adjusting 4 things and they are draft depth, draft position, twist and angle of attack. Unless you understand those 4 element completely, sail trim will never make any sense. In the first chapter of my book I explain those elements and tell you that if you don’t understand them don’t proceed until you do. Next, you have to know which of the 4 elements each mainsheet and jib control adjusts. If you don’t know your just guessing So here is the bottom line. When your dock neighbor asks you a question about sail trim the first thing you want to think about is what element is he talking about and which control is used to adjust that element. Half the time they are using the wrong one anyway!!
