Winch and Jibsheet Wind Load Calculator

Wind jib sheet load based on the Harken formula with inputs to calculate sail area so it is a little easier to use. The winch recomendation is based on the book "The Complete Rigger's Apprentice" by Brion Toss. Enter boats "J" and either "I" or the luff dimension. Enter sail size in percent to get line load and derating recomendations.
J of boat in feet:
Length in feet:
Jib Size in%
Area of sail in sq ft:

Apparent wind speed in knots:

Force on line is

0 Pounds

Use line with strength greater than

0 Pounds

Recomended winch power ratio is


Load in Pounds = Sail Area * (Wind Speed )2 * 0.00431
Winch power ratio = foretriangle area * 6 / 35
Line load safety factor is 5:1

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