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Last update, December 23, 2009


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Sail materials have been increasing in number during this decade. At the end of 2009 new materials were still showing up at sailmakers that aggressively look for new product. However, by far the most common in use is the laminated Mylar cloth.


Sails are offered singularly and in sets (suits) and also in three different sizes. The EC12 class allows, what are termed A, B and C suits and the dimensions are listed in the Class Rules. The A rig is by far the most popular as will be understood by the descriptions below. This size will carry the maximum sail area allowed by the Class Rules. The B and C rigs are used in higher winds where the A rig incurs too much heel or lack of control. Here in the United States, most serious sailors carry a B rig in their inventory but they are seldom needed. The C rig has been little seen here.


TriSpi 25 (TS25)

This is 0.6 ounce Mylar and almost gossamer to the touch. This weight is used on A rigs for light air rigs. Generally, this will be in nil to three MPH air. Some have is used this cloth for a full suit of sails. Mostly, TS25 is used on a jib with a TS40  mainsail.


TriSpi 40 (TS40)

This is a 1.0 ounce Mylar and by far the most widely used in A rigs and sometimes called a heavy A rig. This sail works well up to around 10 MPH although. However, it must be pointed out, that sail performance is very closely related to the sailor’s skill in tuning, as conditions become more challenging. Having a suit of this cloth is recommended.



This Mylar is 1.2 ounce in weight and is relatively new to fleets in 2001. The cloth is designed with dual re-enforcements that form a "diamond" pattern. It is felt that this helps the sail retain its shape better in the light air conditions. Indeed, despite the weight, this sail has performed well with as little as one MPH air movement. It has also sailed well to 10-12 MPH. While it is generally seen as an A rig, some sailmakers are using this cloth in B rigs. Because the sail seems to be less sensitive to maladjustment it is recommended here to those new to sailing the EC12.


TriSpi 50 (TS50)

This heavy 1.3 ounce Mylar is mostly used on B and C rigs. This would be in wind 12 to over 20 MPH.


Drafting Mylar

This material still offered by one sailmaker but supplies are dwindling. 1.4mil and 2.0mil combine for a light air rig with all 2.0 for a heavy rig. The cloth is very durable and holds well into the high wind range of the A rig. It does wrinkle easily and requires weight at the foot with off the booms.


CPM 505

This is a slightly heavier copy of the famed and gossamer Test 505 cloth. This cloth is popular with some competitors in the 2 to 6 MPH range.


North Sails 355

This is a very heavy laminated Mylar similar to the PX75 for heavy air sailing. This new cloth has just arrived at events and referred to the “Black Sails” which is really smoked.


Main Luff Allowance (MLA)

The MLA represents the amount of convex curve of the mainsail luff. It is sometimes referred to as "Luff Round." The sailor needs to know this measurement from the sailmaker in the course of their decisions in tuning. Pre bend of the mast should match this curve before further tuning. Some sails are cut with no MLA and intended to be on a straight mast.


Jib Luff Allowance (JLA)

The JLA is often referred to as "Jib Sag." It is the sag of the luff created by the wind pressure on the sail. This is measured in 1/32" increments and a #6 jib will represent 6/32" concave round in the jib luff.   Backstay tension increases the tension on the jibstay and allows the amount of sag it assumes for any wind speed to be controlled. If the wind speed is known, then a certain amount of tension is needed on the backstay to keep the jib stay from sagging more than the sailmaker's cut of the jib’s luff allowance. If the jib would tend to sag more that the sailmaker's cut, the luff of the entry angle of the sail will increase reducing the ability of the boat to point efficiently when beating to weather. The result is that the wind has exceeded the design cut of the sails. Too much jibstay sag can be seen on the water as a knuckling of the jib luff indicating a need for more backstay tension.


The higher JLA cuts will represent the higher in wind speed variations the sail will handle efficiently. It is common that as the wind increases so does the fluctuations in speed. Hence, higher sag is generally thought to provide a great range for the Jib. Lower numbers mean less range and then more tuning specific to that range.


This will be covered more in the Pre-Tuning. So, having said all this here is what you may like to know till you have a feel for the sail and the conditions. Ask what the JLA is for the sails you will get. If they are at 6/32nds, you have a wide range within the use of an A rig. If the luff of the jib knuckles (breaking just aft of the luff) increase the backstay tension slightly and accordingly thereafter.


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