The LP of the sail is measured by taking a line through the clew, intersecting the luff at 90 degrees (LP = Luff perpendicular).. so if that measurement on your sail is 12 feet, it’s a 100%; 18 feet, it’s a 150% etc…. The sail in your picture looks to be maybe a 120 or 130 at this angle.

## How is Genoa size determined?

A more precise description of the size of a genoa is given as a percentage. The overlap size is the LP of the sail divided by the J dimension of the boat. The “LP” is the luff perpendicular which is the shortest distance from clew to luff, which always works out to be on a 90 degree angle from the luff.

## How do I determine my sail size?

What Sail Dimensions are Required to Calculate Sail Areas?

- The required sail dimensions for calculating the area of any triangular sails are usually its height and the length of its foot. …
- Area = (P x E)/1.8, where:~
- For the mizzen sails on ketches and yawls, ‘P’ and ‘E’ relate to the mizzen mast and boom.

## How is Luff calculated?

It uses Heron’s Formula to calculate the area of the sail, then uses the basic formula for area of a triangle to calculate the luff perpendicular: area = ½ base × height, solving for height (LP) where the “base” is the luff. The LP is then divided by the J measurement and multiplied by 100 to make it a tidy percent.

## How do I calculate my headsail percentage?

The size of your headsail expressed as a percentage is simply LP divided by the J. For example, if you measured the “LP” at 11′ and the “J” of your boat is 10′, then: 11/10 = 1.1 or 110%. On the same boat a sail with a 15′ LP would be a 150%, (15/10 = 1.5 or 150%). Use the dimensions shown in pink.

## What is a number 1 Genoa?

A genoa is larger, with the leech going past the mast and overlapping the mainsail. … Genoas are classified by their size; a modern number 1 genoa would typically be approximately 155%, but historically number 1 genoas have been as large as 180%. Number 2 genoas are generally in the range of 125–140%.

## What is the difference between a jib and a genoa?

Jibs are typically 100% to 115% LP and are generally used in areas with heavier winds. … Typically a jib will be no greater than 115% of the fore-triangle dimensions. A genoa is similar to a jib but is larger and reaches past the mast. It will typically overlap a mainsail to some extent.

## What is a Code 0 sail?

The Code Zero is a cross between a genoa and an asymmetrical spinnaker that is used for sailing close to the wind in light air. … The sail is very flat and is designed for close reaching. It has a nearly straight luff, a mid girth about 60-65% of the sail’s foot length.

## How is boom length measured?

Boom lengths are taken from the mast front to the leech edge at the upper eyelet at the clew. The tape measure end is hooked on the sail edge just above the eyelet, letting it settle against the eyelet and outhaul line.

## What is luff length?

“P” is the luff length of the main-sail, measured along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted. … “I” is measured along the front of mast from the highest halyard to the main deck. The main deck is where the deck would be if there were no deckhouse.

## What is a number 3 jib?

#3 Jib. A non-overlapping headsail for heavy air use on boats that also carry genoas. This sail sheets inboard of the shrouds and in front of the mast, which allows the mainsail to be eased or traveled down without backwinding.

## How big should my spinnaker be?

The rule of thumb for the spinnaker size is the luffs = I. The foot should be between 1.6 x J and 2 x J. Many cruising boats are now using “Poleless Spinnakers.” The luff on poleless spinnakers should not exceed the I or the full size genoa luff. The foot should be between 1.6 and 1.8 x J.

## What is luff and leech?

Luff -A sail’s forward edge. … Leech – The sail’s back edge. Foot – The bottom edge of the sail. Tack – Between the luff and the foot is the tack.

## What is a gennaker sail?

A gennaker is a sail that was developed around 1990. Used when sailing downwind, it is a cross between a genoa and a spinnaker. It is not symmetric like a true spinnaker but is asymmetric like a genoa, but the gennaker is not attached to the forestay like a jib or genoa.

## What is a spinnaker sail?

A spinnaker is a particular type of sail designed for use when a boat is reaching or sailing ‘off the wind’. For example, when on a broad reach or run. … The larger the sail, the more wind a spinnaker can harness and so the more power may be provided.

## How does a self tacking jib work?

Basically, the sheet from the jib is led to a car which moves across the boat when the boat tacks-very much like a mainsheet traveler. Tracks vary from straight across the boat, to bent track with the ends forward, to bent track ends-up and then tilted forward.