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post #63 of Old 06-22-2010
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While thinking about weather helm, you should realize that it is not a fixed thing on a boat. While mast rake and other factors will combine to produce weather helm, lee helm or balanced helm, the specific loading of the boat and the configuration of the sails will affect it significantly. Weather helm or lee helm are largely determined by the relative position of the center of effort of the sails (COE) and the center of lateral resistance of the hull (CLR). The further forward the COE relative to the CLR, the more lee helm; the further aft the more weather helm. Thus, weight distribution on the boat can affect the fore and aft tilt, and the position of the COE. Usually the center of lateral resistance stays about the same, though this is not true with a lifting keel or centerboard. Lots of weight in the bow will tilt the boat forward. Lots of weight in the stern, the reverse. For example, heavy anchor chain moves the weight forward and thus the COE. On my boat there is a 42 gallon water tank near the bow. 42 gallons filled equals about 350 pounds. Thus the state of the tanks can affect weather or lee helm. In addition to the fore and aft balance, the sail plan will move the COE. Bigger jib moves the center of effort forward. No jib moves it aft. Reef the main and the COE moves forward. Reef the jib and it moves aft. As you adjust, learn about the variables and plan for them. Some sailors tend to ignore slight weather or lee helm in lighter conditions, but this can be a big mistake, because the effects will be greatly exaggerated when the wind pipes up. Most people want slight weather helm in normal conditions. Too much weather or lee helm slows the boat because of the drag from the rudder. Slight lee helm in light winds means strong lee helm in that sudden gust, and that lee helm means you can't turn to weather to spill wind and can be very dangerous. Slight weather helm in light wind may mean strong weather helm in strong winds, but strong weather helm will turn the boat into the wind, a much safer result.
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