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U20 Boat Maintenance & Care / Re: Forestay/Jib adjustment
« Last post by Dean Nelson on May 30, 2026, 09:42:31 PM »There are multiple thoughts on mast rake, which varies by boat design. For the U20, the recommended mast rake is between 34'9" and 35'. Here is an AI response to mast rake in high wind: With high wind, should there be more or less mast rake to a sailboat? In high winds, you should generally have less mast rake (a more upright mast) on a standard keelboat or monohull to prevent excessive weather helm. However, the exact rule depends entirely on your specific boat class; for example, many high-performance beach catamarans, skiffs, and foiling boats actually utilize more mast rake in heavy air to de-power the rig and drag the boom close to the deck. The mechanical trade-off depends on how your specific vessel balances two opposing forces. Standard Monohulls and Keelboats: Less Aft Rake For traditional monohulls, high winds cause the boat to heel significantly. Heeling naturally forces the boat to spin up into the wind, a phenomenon known as weather helm. The Problem: Raking a mast further aft moves the sail plan's Center of Effort (CE) backward. This generates even more weather helm. The Solution: In heavy air, shortening the forestay to pull the mast more upright (less rake) shifts the sail power forward. This counters the rounding-up effect, neutralizes the steering, and reduces massive rudder drag. Rig Tension vs. Rake: On standard boats, do not confuse mast rake (the static tilt of the spar) with mast bend (curving the middle of the mast). In high winds, sailors crank down on the backstay. While this slightly alters rake, its primary purpose is to bend the mast, which flattens the mainsail and spills excess power. Performance Catamarans and Foiling Boats: More Aft Rake On multi-hulls (like a Hobie 16) and modern foiling classes, the conventional rule is often flipped upside down. The Aerodynamic Goal: In high winds, these boats suffer from extreme overturning lift. To combat this, sailors rake the mast as far back as the rigging allows. The End-Plate Effect: Shifting the mast aft lowers the boom closer to the trampoline or deck. This seals the gap beneath the sail, channeling wind efficiently across the sail skin rather than letting it escape underneath. De-powering the Top: The radical tilt allows the top of the sail plan to cleanly twist out and spill overwhelming wind gusts, while keeping the boat's driving force closer to the water level to prevent a pitchpole (capsizing forward). Any resulting heavy weather helm is physically corrected by raking the rudder blades forward rather than altering the mast.