High tech sails on fastest 18 footers
by Colin Groves on 21 Dec 2007
The 18ft skiffs have always been a hot bed of development, and more recently, the pace of sail development has been significant with North Sails 3DL leading a new development phase.
FIAT winner of the 2007 JJ Giltinan 18 footers Christophe Favreau © http://christophefavreau.photoshelter.com/
In the 2006/07 JJ Giltinan 18ft Skiff Championship a battle royal waged between first and second place boats. In the end only four points separated the winning ‘Fiat’ team from the second placed ‘Gotta Love It 7’. There is a story behind this battle to be recognised as the world’s best 18 footer team. Sail-World spoke to North Sails Michael Coxon about how his company assisted the top two boats.
North Sail’s Michael Coxon is the namesake and uncle of the winning 18 ft skipper. He is also called Michael Coxon more often ‘Cocko’. To keep things simple, we’ll call the Fiat skipper ‘Mike’. Michael tells the story so far…‘Mike won the 05/06 Worlds and he got the approval to do a new boat (from the Australian 18 footer League Club).’
‘A month before the season started the previous sponsor pulled out and said they weren’t going ahead. He was basically looking at having a boat, but no sails or rig.’
Michael called on yachting legend Neville Crichton who came to the party with sponsorship from 'Fiat '. At the same time, Iain Murray was given the task of returning the Channel 7 name he won 6 world titles with in the 70’ and 80’s. Iain and Michael then set a plan to begin a sail development program using the two boats to test with.
North Sails got stuck into constructing the best sails they could for Fiat and the Channel 7 boat. ‘People hadn’t used 3Dr sails before on 18 footers; it is allowed by the rules but this is the first ever set.’ ‘We wanted to do moulded sails, and we wanted to do different rigs. Basically we had an opportunity to play with the rigs, where the sailors and the sponsors were committed to working with us.’
‘The first set of sails made for Seven were a set of panel sails, to experiment with different masts and race profiles. The second generation was moulded 3Dr sails for both boats.’
Like many good ideas, making sails on a three dimensional mould seems obvious in retrospect. Sails are not flat, so why construct them from flat, two dimensional fabrics? The inspired notion of building a three dimensional shape with a single piece of fabric was born late last century.
North Sails started making moulded three dimensional sails in the early 1990’s. The 3DL™ sails are constructed from a seamless piece of fabric. Executive Vice President Jay Hansen explained the evolution of the three dimensional technology.
‘In the 1980’s we made paneled sails. At the time we were one of the few sail makers that actually shaped the seams of all those panels; most sail makers would put them together flat which was far easier, it didn’t make quite as good a sail, but it was far easier.’
‘We began discussions about three dimensional sail manufacturing in 1989 with J.P. Baudet and in 1990 we began development. Comparing the 3DL product to our own paneled sails, which we could do in hundreds of cases, we quickly realised the 3DL product was far better than we expected it would be.
‘We learned the reason why, was that each individual yarn in a 3DL product was doing a more efficient job, yarn by yarn, than it could do in any kind of panel sail. Not only because it was continuous but more because it was lying in a three-dimensional plane, something it could not do in a panel sail or in other two-dimensional sails.’
‘The big difference was 3D versus 2D.’
With about a month before the Championship, Michael Coxon wanted the sails for both 18 footers to be as efficient as possible. They experimented with sail shape and trim on board the Channel 7 boat using the paneled sails.
‘The panel sails did the development on the Channel Seven boat before Fiat was launched. We went out a month before hand and did all of the development, signed off on what we liked and did some recuts before she hit the water. We then produced some moulded sails for Fiat.’
It became like a high speed controlled experiment. Take two boats with two highly skilled crews and identical rigs. Then pit them against each other to see whether paneled or moulded sails perform better.
‘They then went two boating; they were identical rigs and identical sails in every way apart from the fact that one was moulded. In line-ups Fiat would beat Seven around 60/40.’
With time running out, North Sails built a set of 3Dr™ moulded sails for the Seven team.
‘The new moulded sails were a big advantage. The two boats just got faster and faster. More importantly they were fast through a high wind range. They would often sail from pretty average starts and then the majority of the time end up in the top three. The chance to win a race with time to spare was just amazing.’
Sail-World asked why the moulded sails performed so much better than the paneled version. He said it relates to the profile shape of the leech of the sail when it’s under load. ‘The biggest difference we can see when we try and explain why the moulded sails are so much faster is the leech twist. They are way lighter as well.’
At the same time that Coxon was engaged in the intensive development of the 18 footers sails, North Sails world –wide was engaged in refining moulded sail production techniques. Three dimensional sails have been so popular that at times the company has had trouble keeping up with orders.
‘From the beginning of 3DL we realised the labour content was still quite high and it was a relatively expensive sail to make, even though the process made a better sail’ said Jay Hansen.
Currently the 3DL™ sails are produced on a gantry mould. Mylar film is laid down first over the curved male mould. The film is covered with special glue and then a computerized loom lays down Kevlar Aramid yarn. Kevlar and Aramid are synthetic fibers with high strength to weigh ratios. The pattern in which the yarn is laid down corresponds to the expected stress points on the sail.
After this another film of Mylar is applied and then the sail is vacuum bagged and heated to cure the laminate. The resulting product is lighter than a paneled sail and held to its designed shape.
North Sails has just started producing moulded sails on a new rotary loom in the company’s 3Dr facility in Toronto, Canada. The expected result is a reduction in sail delivery times with smaller keelboats and one designs able to utilize three dimensional moulded sail technology.
‘The 3Dr machine will produce smaller sails at about ten times the rate of the 3DL moulds. This will allow us to increase sail production capacity for larger sails on the 3DL moulds.’
Not one content to rest on their laurels, Michael and the team have been pushing forward in the news 2007/2007 season with a new radical head profile, revised sail shapes and new Southern Spar rigs. So far the results have been encouraging and the sails turning heads. A new development phase has begun and we’ll have more news and images before the World titles.
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