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Ask Sail: Staysail Loads

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By using sail area and expected wind speeds, you can easily estimate headsail loads

Larry Schnell, Cooperstown, NY
Q: I would like to add an inner forestay to my Hughes Columbia 40. The sail for this is 350 square feet. What safe working load would I need for an exit block for the mast as well as jib tracks and leads?

Win Fowler Replies
A: The load on a sail is proportional to the sail area times windspeed squared. The formula is: (sail area [in ft2] x windspeed2 [in knots]) coefficient = load. In our shop we use a coefficient of 0.00431. For a 350ft2 sail in 30 knots this yields a load of 1,358lb. In 40 knots of wind, the load climbs to 2,414lb. We assume that this is the load on both the sheet and the halyard. I would think a safe working load of 2,500lb would be pretty good.

 

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