How is sail area calculated?

What is sail area?

The Sail Area-Displacement ratio (SA/D) is a calculation used to express how much sail a boat carries relative to its weight. In the first equation, the denominator in pounds is divided by 64 to convert it to cubic feet (because 1 cubic foot of salt water weights 64 pounds).

How sails are measured?

While the sail is still laid out go to the Tack and lay the tape along the luff of the sail as if you were extending the edge downward. Draw an imaginary line to the intersection of where the Luff and Foot would meet normally, this is the measurement you need.

How is upwind sail area calculated?

Calculating Sail Area

To find the area of the triangle in square feet, just multiply the two together and divide by 2 (100% foretriangle = (I x J) ÷ 2).

What are sailboat calculations?

The traditional calculation for SA/D compares sail area in square feet to displacement in cubic feet. In the formula, displacement in pounds is divided by 64 (the density of seawater) to obtain cubic feet, which are in turn converted to square feet to make the ratio unit-free.

How is hull speed calculated?

Hull Speed Formula

Theoretical displacement hull speed is calculated by the formula: velocity in knots = 1.35 x the square root of the waterline length in feet.

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How do you calculate mast height?

If the dowel looks a bit shorter, simply scoot the dowel up on the knot. When you finally set the dowel so that it is the same height as the tallest item on your mast, simply add this distance to your messenger line (or true mast height if you calculated it) and this will be your actual mast height clearance.

How is Genoa size determined?

The best way to measure the tape is to use Calipers that can measure in millimeters. If you don’t have a set use a set of drill bits and either slide them up the track in your furling system or hold them up to the luff tape on your existing sail to determine the proper size.

How do you calculate boat displacement?

The volume below the float plane times the weight of water (fresh is 62.4 and salt is 64.) equals the displacement of the boat. The displacement of the boat minus the boat weight divided by five is the maximum safe load.

What is Bal disp?


A Bal./Disp. ratio of 40 or more translates into a stiffer, more powerful boat that will be better able to stand up to the wind.