Running Rigging Load Calculator

Calculate sheet and halyard loads for proper line selection

Total area of the sail in square feet. For a mainsail, use luff x foot / 2. For a genoa, use luff x LP / 2.
sq ft
Apparent wind speed in knots. Sheet loads increase with the square of wind speed. Design for maximum expected conditions.
knots
Mechanical advantage of the sheet or halyard system. Simple 1:1 = 1, 2:1 purchase = 2, etc. Winch adds further reduction but does not change line load.
:1
Polyester (Dacron): standard, moderate stretch. Dyneema/Spectra: high-strength, minimal stretch, expensive. Nylon: high stretch, good for anchor rode.

Results

Sheet Loadlbs
Halyard Loadlbs
Recommended Line Diametermm
Breaking Strength Margin:1
Stretch Estimate%
References: Sail load formula: Force = 0.00431 × V² × Area (lbs, knots, sqft). Halyard load typically 40-60% of sail force. Safety factor: 3:1 minimum for running rigging (Brion Toss Rigger's Apprentice).