# Sail Dimensions and Details

## Sail Dimensions and Details

Sailmakers require specific measurements in order to make up a sail. These are known as the **p, e, i, j,** figures and can be useful to find the lengths of the mast and boom.

**p** is the length of the luff of the mainsail from the top of the boom to the highest point a sail can be hoisted.

**e** is the length of the foot of the mainsail from the goose neck at the mast to the furthest point along the boom a sail can be fixed.

**i** is the length from the genoa/jib haliard at the top of the mast to the deck level, **not** the coach-house roof.

**j** is the length from the fixing point of the foot of the foresail to the mast at deck level, **not** the coach-house roof.

**py** and **ey** respectively apply to ketches and yawls and are the luff lengths and foot lengths of the mizzen sail.

**iy** and **jy** apply to staysails and are the halyard to deck, and staysail foot to the base of the mast measurements respectively.

Racing Boats will have a black band on the mast and boom to signify the measuring points for these figures.

**Foresails**

Foresails that reach up to the mast (J = less than 100%) are called Jibs. Foresails that extend past the mast (J = greater than 100%) are called Genoas.

Jibs usually come in 3 sizes, No1 Jib or Working Jib, No 2 Jib, and No 3 Jib also called a Storm Jib. Their names developed from the old sailing ships.

Genoas usually come in 2 sizes. 155%J Genoa or 135%J Genoa although these sizes tend to get blurred. A Genoa larger than 155% becomes over-powerful and the nose of the boat will be blown away from the wind.

Cruising Chutes and Spinakers tend to be around 165%J

Formula for Working Out Sail Area knowing only the lengths of the sides of the sail

Area = SQRT(s*(s-a)*(s-b)*(s-c)) where s = (side a + side b + side c)/2