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Flying Moth development
Thursday, 25 February 2010
The International Moth worlds is due to start in Dubai in a week’s time, and over the winter the Hyde team has been working hard developing a new version of their winning mainsail design.A keen Moth sailor himself, Hyde Sails' Technical Director Mike Lennon explains: "With such an early world championship In Dubai this March, we wanted to move our Nationals-winning 2a design forward over the winter. However, the weather to date has not been kind and this has only allowed three iterations of the design. The development is further complicated by the need for three different luff curves. The 2a design is very much based on masts from the more flexible end of the spectrum and our winter program was very much aimed towards the stiffer end."
The basic elements"There are several basic elements in the sails to be considered and perhaps the most influential is the shape on each side of the sleeve. The sleeve acts like a wing mast but the amount of rotation available is set by a combination of the shape on the front (luff curve) and the shape on the sleeve to sail join. Plus the flexibility of the batten tips out of the cams. The cams them selves can also have some effect.
"Outline shape is free so you can have massive square tops or super long foot so long as the surface area does not exceed 8sq m. The problem is that in marginal foiling and downwind always you want the area high and the sail deep. But upwind once foiling you need a quite flat draft forward shape. We tried a smaller head and wider lower/mid area but both myself and Richard Lovering didn't like it. We felt we could not get as good a VMG down wind. It seems easier to deal with over-full sails upwind, than power-up flat sails downwind."
The data verses on the water testing"We have also been doing some pure aerodynamics with Kevin Ellway (Ninja designer) and although my experience told me some of the data he was feeding us didn't stack up with on the water work, we did made a very radical sail for Mike Cooke to try. This sail did influence the thinking in the more conventional work on the 2a modification. So we shortened the foot and added the area to the mid roach whilst keeping the large square head. This acts as a simple lever, power high
er up meaning you have to bear off to de-power making you sail deeper angles. No rocket science in that, but a lesson remembered! We are hoping the shorter foot and wider mid section will reduce drag without reducing lift. Although it's understood this potential gain is pretty small compared to getting the shape right."The result
"So we have ended up with less luff curve – a flatter, but wider mid section and shorter, but deeper foot section. The sleeve is slightly narrower, but has as much shape at the sail join. The top batten now shares the last cam whereas on the 2a there is a gap. This makes the twist profile smoother as in most Moth sails the top batten is not on a cam so you get less compression through the batten, allowing the twist between the top and second batten down to be inconsistent.
"The new sail for stiffer rigs (the 2B 2010) is still made from ODL04 as it's very light and very low stretch, but we have reverted back to dacron luff panels to make downhaul application more progressive.
Looking ahead to the worlds"The World Championship should be a welcome relief from the UK winter with air temperatures in the late 20s and the sea in the early 20s. Light to moderate breeze is what's expected and looking at Windfinder and Windguru predictions for next week of around 10-15 knots, conditions should be ideal although it has been down at 6 and as high as 30 in the
last week or two, so I would expect the unexpected. The last two worlds have been on sheltered waters, but this is on the open sea so bigger waves may also have a role if it's windy. Moths are tricky downwind in larger swells. Last year's UK nationals was won and lost on who pitchpoled least!
"I would imagine that Bora Gulari (USA) will go in as favourite having spent most of the winter in Miami training to top up his already impressive skill level after winning last year's worlds.
"Watch out for the UK's Simon Payne in a mixed wind or light wind week; he is up foiling early up and quick downhill in the marginal stuff. He won one of the few light air races at the Gorge last year by a leg. Nathen Outteridge (AUS) (not currently entered) now has a Mach2 after finishing second last year in a Bladerider, the Mach2 may well give the extra
little bit needed to win.
"The boats are becoming more and more sophisticated and most are now adjusting ride height around the course and from tack to tack. Sail development has taken off after years of domination from KA. Also there are a lot of different mast sections available in the mix. There are rumours of wand dampers and built in slop in the flap to wand mechanics plus gearing adjusters to alter the wand to flap ratio of movement. The boats are getting quicker and the sailors' understanding of what matters is improving. It's going to interesting to see what comes next."
For more details on Hyde's Moth sails or their development, contact Charles Devenport on +44 (0)845 54 38 957. or email: charlesdevenport@hydesails.com
posted by Hyde Sails at
04:25
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