Sail-area calculator
Reference areas for … rig configurations — the standard production rig for each boat, in square metres. Not in the list? The rig triangles below give the nominal areas from P, E, I and J.
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From the rig triangles
If a boat is not in the list, its nominal areas come from the four rig measurements. These are triangle areas, not cloth areas — see the note at the foot of this page.
Why a rating figure and a sailmaker's figure differ
Sail area is the surface of the finished sail. For a triangular sail with no roach it is close to ½ × luff × foot — but the moment you add roach or belly, that formula understates it, and the real area comes from the actual outline. Rating rules and brochures usually quote a nominal area from the rig triangles (P×E÷2 and I×J÷2), which is not the same as the real cloth area of a roachy full-batten main. The listed areas above are reference areas for the standard production rig — indicative, and worth confirming against the actual rig before anything is cut to them.