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Melbourne: Etchells Radial Cloth Headsails

22 October 2014 Noel Drennan

J1R in 12kn TWS

"J1R in 12kn TWS"

Photo by:
North Sails

With the creation of North Sail's own and Patented, 'Radian Olympic' (Oly) warp orientated Dacron, the next logical step was to create the full radial cut headsail to compliment our radial mainsail development program. Oly has been specifically designed to meet the Etchells class minimum main and jib cloth rules.

Radian warp cloth allows us the flexibility during design to orientate and align each panel with the curved high load path from the head and clew.

Conventional crosscut cloth has to be laid out at 90 degrees to the load line, which limits the designer to alignment in just one plane.

The Etchells headsails aspect ratio at 3.16 to 1 is extremely high, as compared to most other 30-foot yachts. Sail loads increase with the sails aspect ratio, making warp construction ideal for locking in and then holding the shape of an Etchells jib.

Following on from our two-year development program with radial mains, we have been working away at developing a mould for our Full Radial Etchells headsail since November 2012. Our first Radial headsail, coded FLR, had a large radial clew and radial head and cross cut middle section. The cross cut mid section provides our designer a stepping stone in the design process, so we stay in sync with our multiple world champions' cross cut sail designs.

Have a look at the sail analysis

It is interesting to note that for much of our testing we minimise variables by testing a radial main with our proven cross cut jib and vice versa. We are now far enough down the track with the mains that we now can test both radial sails together.

We are currently testing three, full radial jib models of varying depths in Melbourne, Sydney and San Diego.

With North Sails again winning the recent Newport Etchells World Championship, our proven cross cut sails remain our benchmark and default models of the market. With the full radial models, our goal is to take advantage of new technology, not fashion, which we have observed in some Dacron markets, where fill (cross cut) orientated cloth as been incorrectly used. As such, we are under no time pressure to finalise designs and have introduced a limited number of sails to the market, which we are confident that these models are competitive. Our testing team includes top sailors such as Tom King, Graham Taylor, Grant Simmer, Ian Murray and Mothy Jarvin, who together with myself, Michael Coxon and Richie Allanson give feedback to our designer, Andrew Lechte. Andrew is regarded as a world leader in radial one design sails, having successfully introduced radial sails to other classes, such as the Star at Olympic level.

You may be surprised to find out that the headsail provides most of the driving force on an Etchells, despite of its small area, offering around 65% of the total forward drive.

The headsails efficiency is gained from the flow onto mainsail behind it, and whilst sailing we tend to focus most of our attention on the main, as it is more visual to the crew, critiquing the mainsail shape, which is often at the expense of the jib.

The importance of headsail trim and set up is often under rated, as in the Etchells we have many trim adjustments, sheet tension, halyard tack/forestay sag, in-hauler etc.

On my boat I have a measurement marked on my jib cars as my base position at 2600mm from the forestay, marked on both port and starboard tracks. This base position becomes my jib car base for trim reference.

In summary, the advantages of the radial construction are:
- a smoother moulded shape achieved through multiple panel vertical shaping,
- improved shape holding through yarn alignment, giving longer racing life,
- lighter weight with greater wind range,
- the creation of computer moulds for ease of both reproduction and subtle design tuning for future development.

The end result gives us a lighter, smoother, longer lasting shape holding jib built to the class minimum cloth weight of 270gm.


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