Triangular Sail Measurements
Measurements for triangular sails for all US VMYG classes are based on the Vintage Marblehead rule and as was specified in the 1958 MYRAA Handbook. Note that:
- Rig and mainsail measurements are taken from the underside of the 0.75-in base of the mainsail headboard.
- Only the “triangular” sail area, excluding roaches and the rounded foot of loose-footed sails is measured.
Enter the lengths of Sides A, B, and C in inches (and decimals) to get sail area in square inches.

4-Sided Sail Measurements
To figure the area of a 4-sided sail, draw a diagonal that divides the sail into two triangles: one with Sides A, B, and Diagonal and one with Sides X, Y, and Diagonal. You can use either diagonal, but Sides A and B must be from one triangle, and Sides X and Y must be from the other.
Enter the lengths of Sides A, B, X, Y, and Diagonal in inches (and decimals) to get sail area in square inches.


Fractions to Decimal Table
| Fraction | Decimal |
|---|---|
| 1/16 | 0.0625 |
| 1/8 | 0.125 |
| 3/16 | 0.1875 |
| 1/4 | 0.25 |
| 5/16 | 0.3125 |
| 3/8 | 0.375 |
| 7/16 | 0.4375 |
| 1/2 | 0.5 |
| 9/16 | 0.5625 |
| 5/8 | 0.625 |
| 11/16 | 0.6825 |
| 3/4 | 0.75 |
| 13/16 | 0.8125 |
| 7/8 | 0.875 |
| 15/16 | 0.9375 |
