VMG vs Boat Heading
Performance sailors use the acronym VMG (Velocity Made Good) to express boat speed relative to the direction of the wind. The concept holds that for any given sailing condition and desired course, there is a single combination of boat speed and true wind angle that equates to the optimum VMG. On any point of sail -upwind or down - the longer we can maintain the best VMG, the better our cumulative performance.
VMG = boat speed x cosine (angle sailed to the true wind). In this particular example, it can be seen that by bearing off to an angle of 57 degrees to the True Wind, one can optimize VMG to one's destination. Although one will sail a longer course, VMG will be higher and one will arrive at one's goal faster. VMG depends on the polar speed diagram of one's catamaran and the cosine of the angle sailed to the True Wind.
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