Booga Booga Member
Join Date: Oct 2006
Location: Bowen Island
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What you may find is that the bigger the sail, sometimes is not the answer to make your boat go faster or reach her top speed. As mentioned, you may make the boat heel too much and lose power. It matters if your sail has been blown out, how well it keeps its shape, etc. I know that my working jib is a much better and more powerful sail than my gennys going to windward and holds its shape better. Obviously wind strength plays a big role to achieving your top speed as well.
Also, how much weight or extra weight do you have on your boat? When was the last time you cleaned her underside? Do you have a jib pole? Are you reaching or running the boat to get top speed? Each boat has a slightly different optimum point of sail.
I find the best way to get that last little drop of speed out of your boat is just play around with it and watch your tachometer or gps on a steady wind day as someone else mentioned because every boat is different. One of your best and simplest trim tactics I agree would be your tell tales. Olympic dinghie racers will tell you that their best trim tool is a tell tale - Its your best way of visualizing smooth flow of an invisible substance.
My formula: 1 start by holding your course and setting your sails to just above luff point, maybe a little tighter. Watch your telltales. Make sure they fly straight back on both sides of the sail.
2 On your foresail, make sure your foot and your leech are firm, and not flapping This is important because it may mean your block is too far forward or back. Watch your telltales and adjust your jibsheet after you have set the block.
3 On Your Main, check your outhaul. You can lose a lot or gain a lot of power with a small adjustment here. Make sure it isn't too tight (close hauling or high wind) or too loose. You can tell by using your tell tales. All of them up and down the forward edge and the trailing edge of your main should be streaming back. Make sure the sail is not twisted too much in a vertical sense, if it is, adjust things until it isn't (vang, main sheet, outhaul, topping lift). Telltales will let you know when everything is right.
Your backstay tensioner can also make a difference, again, use your telltales.
You would only really worry about your mast rake from the backstay if your main sailshape is too flat. Usually, dont even worry about the backstay.
the rule of thumb for sails is that the more you let them fill or more rounded you let them fill, the more power you get out of them. Think of an airplane wing. However, as the wind picks up to high you don't need as much power and you flatten your sail out. tighten things to flatten that wing shape.
Of course you can refine your trim even more with other little things.
Use your telltales, they are invaluable. Play around with all your gadgets until your telltales fly true. Its that simple.