Sail Buying Tips


These tips mainly apply to stock sails but are also good to know if you plan on making a custom sail. Sail measurements published in the search results describe the sail fully stretched so it will never exceed those dimensions under normal halyard tension. Remember, you can use a sail that is short on the luff or foot but you can’t use one that is too long! Be conservative. Refer to our Measuring Guide for the best way to measure.


Luff Length (or “P”) - Our recommendation for mainsails is to stay within 95% of full hoist. but not so high the headboard interferes with the backstay. Best to stay at least 4-5” inches short of absolute full hoist.

Foot (or “E”) - Again stay within 95% of max foot length unless your intent is to de-power the boat or decrease weather helm.

Cloth Weight - The mainsails we stock are built with appropriate cloth weight for their square footage and the boat size they are intended for so you shouldn’t have to worry about this unless you have some unusual requirements. Offshore sails are made a little heavier for offshore work. Call us if you would like a cloth weight consultation.

Luff Hardware - Hardware for stock sails is published in the search results. The slugs or slides that come on a stock mainsail may or may not be the same as your old ones. Therefore changing the luff hardware on a mainsail is sometimes necessary. Our In-Stock mainsails have grommets on the luff so you can easily remove the stock hardware and shackle on your old slides or slugs onto the grommets. Or we will change the hardware here for you for $4 per foot of luff ($65 minimum) before shipping. Alternatively you may custom order any of our sails to be made with your choice of luff or foot hardware at no extra charge.

Jibs (non furling)

A “jib” is normally a small working headsail intended to drive the boat in a good breeze, about 8 knots or more. Here are our recommendations:

Luff Length - Working jibs for production boats usually are not “full hoist” which means the luff does not go all the way up the headstay. We recommend that the jib hoist be anywhere from 90% to full hoist. You may go less if you want to depower the boat (common in high wind areas).

Overlap - Working jibs normally fall between 90% and 115% overlap. This means the jib’s L/P dimension is between 90% - 115% of the distance from the bow of the boat to the mast (known as the “J” dimension). High wind jibs would normally be less than 90% in both hoist and overlap

Cloth Weight - Jibs normally have a cloth weight approaching that of the mainsail. This is because they are intended to be used in higher winds and need more strength and stretch resistance than the genoa.

Genoas (non furling)

A genoa is normally a large, relatively light headsail intended for use in light air, usually 12 knots or less. Here are our recommendations for genoas:

Luff Length - Since this is your power sail the luff length should be no less than 95% of the full hoist unless you are willing to sacrifice power.

Overlap - A full sized “genoa” is usually no more than 155%. Larger than this will cause a racing penalty under most rules. Excessively large genoas may choke the main by closing the “slot” which makes it less efficient when close hauled going to windward, so bigger isn’t necessarily better. 130% - 155% is usually a good size for a genoa. Remember that the genoa’s L/P dimension (luff perpendicular) is what you compare to the boats “J” to figure percent overlap, not the foot dimension. See our % Overlap Calculator

Cloth Weight - Genoas on boats under 30 feet are typically in the 3 to 6 oz weight range. Over 30 feet 6 oz or more is pretty common as an “AP” (all purpose) genoa. The weight determines how much wind it takes to fill the sail.

Roller Furling Headsails (Also know as “Roller Reefing Sails” )

These can be either jibs or genoas depending on the amount of wind you normally sail in. One advantage of having a furling sail is that you can start out with a larger genoa and reef it into a jib as the wind increases. Recommendations:

Luff Length - If you are just converting to a furler refer to our Luff Calculator to see what the maximum the hoist will be for your installation. Furling genoas should be around 95% or more on the hoist. A luff that is shorter than full hoist is better for visibility under the sail and to avoid chafing on the pulpit. Furling jibs are normally 90% hoist or greater.

Overlap - The most popular size for an “all purpose” furling genoa is between 130% and 140% overlap. This is large enough to drive the boat well in light wind yet still can be reefed down to a working jib when the wind picks up. Furling genoas are reefable by about 25% before the sail shape begins to get baggy and the pointing suffers. Foam luff pads increase reefability by up to 10%. If you are sailing in a predominantly windy area (San Francisco or Hawaii for example) you may prefer to use a smaller Jib of 90% to 115% overlap known as a “Blaster Jib.”

Cloth weight - Since furling genoas are normally intended to be reefed to working jib size they should be of equivalent cloth weight. A furling genoa will often be close to or slightly less than the weight of a mainsail on the same boat. Typically; 5 oz on a 22’ footer, 6 oz on a 25 footer, 7 oz on a 30 footer and 8 or more on a 40 footer. Furling jibs should be built heavier, typically about the same weight as the mainsail.

Luff Tape Sizes - The luff tape used in our In-Stock sails are #6 which has a 3/16” diameter internal bead. With dacron covering it slightly increases the total diameter to just less than 1/4”. It is the proper size for most common roller furlers like Harken, CDI, Hood (most), Schaefer (except Snapfurl), and Profurl.