Sailing performance guide
Sail area to displacement ratio (SA/D)
SA/D is a dimensionless indicator of sail power relative to the weight the rig must drive.
SA/D = sail area (ft²) ÷ [displacement (lb) ÷ 64]^(2/3)
What it measures
Higher values generally indicate more sail power for the boat's displacement. The result depends on which sails are included, so comparisons require a consistent definition.
Limits
SA/D does not capture righting moment, hull drag, reefing practice, or sail efficiency. Use it alongside displacement, draft, stability, and the intended sailing program.
Apply it to a real design
Calculate these metrics for a sailboat, then compare the result with catalog models.
Open the calculator