Sail Material

Last update, January 4, 2002

Needs to be updated

Currently, Mylar is the dominate material used by EC12 sailmakers. This material is available in two different designs and a total of four different weights. Dacron 3-ounce material has been used and is still offered by some sail makers. None has been seen in operation in recent years.  A 2.2 oz stabilized nylon with the feel of the previously available 2 oz Dacron is also being used for skippers who want the traditional look of the original 1965 – 1975 model.  The weights listed below are the weight of the cloth by the sailmaker's yard (36” x 28 ½”). The heavier the cloth the heavier the feel and stiffness.

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 captains carry a B rig in inventory but they are seldom needed. The C rig has been little seen here and the only such rigs ever seen in competition were in New Zealand on rough waters in winds exceeding 30 knots.

TriSpi 25 (TS25)

This is 0.6 ounce Mylar and almost gossamer to the touch. This weight is used on A rigs for the most light air conditions. Generally, this will be in one to three MPH air. Likewise, the reinforcements at the corners of the sail are also lighter and less stiff. Some captains will build lighter weight rigs for this wind regime.

TriSpi 40 (TS40)

This is a 1.0 ounce Mylar and by far the most widely used in A rigs. This sail works well up to around 10 MPH although, we have used it into the high teens. However, it must be pointed out, that sail performance is very closely related to the captain’s skill in tuning. This extends to the use of lighter cloth in heavier air. Many will sail this cloth into higher winds because they inventory nothing heavier and have learned to do so by necessity.  Heavier weight head panel material can be used to stabilize the top seam panels where distortion first appears in winds over 8 – 10. It is for this reason you will occasionally see a single suit of sails incorporating different weight cloth.

PX75

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 into the high teens with gusts over 20 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 or the EC12.

TriSpi 50 (TS50)

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

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 captain needs to know this measurement in the course of their decisions in tuning. When ordering sails, discuss this with the sailmaker to understand their thoughts when tuning the main sail. There are preferences based on need and experience that will be better understood as you ponder the varied thoughts on tuning. Generally ¼” is a middle of the road choice that provides an “acceleration” sail shape with a straight mast in light air, and a “top speed” sail shape, when backstay tension is increased to bend the mast to match the MLA in heavier air. Now, having said that, your sailmaker may give you reasons not to have this luff round. You do what he says till you think you know.

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 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, it is recommended that one new to the class or the EC12, order a #6 jib with their A suit.

There is a chart in "Optimizing the East Coast 12-Meter" by Ragged Symmetry Publications, as to backstay tensions versus wind speed. While this would be helpful as a starting point, it should be noted that 1/32" inch is a very small measurement. The chart is offered here as a reference but serious captains have their own for each set of sails in inventory. This will be covered in the Pre-Tuning section and other tuning discussions here on the site.

Reference

For those of you that would like to read deeper into explanations that touch on what is written above, the following links are to copies of documents provided here by Rod Carr of CarrSails as are posted on his website. The wind/sail chart closely supports our observations on the water though presented in a more researched and detailed way. It is interesting study and worth the while as additional information. Please note the model for lake wind speed percentages is at Lake Washington, east of Seattle and will not represent your sailing location or that of the next regatta you may attend. However, the chart is a view of the future, the only one you will have before this monitor and the season ahead.

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