Wednesday, 6 June 2012

Sail and mast development

(click on pic)

Mast Development

We will officially introduce our mast at the Europeans. We have tested the mast for two years now and are happy now both with the performance, the looks and its strenght.

The whole idea was to make a mast which was both faster and stronger than the existing masts as we felt that the mast was the weakest part in the pakage. Mast breakages are not good for the class and with trapezing downwind you have more hard crashes.

We choose to make a tapered mast which is slightly wider in the bottom and smaller and thinner in the top.
The profile in the bottom is slight rounder and becomes flatter in the top.
The shape has four advantages:

  1. It suits the soft fore aft style better as the mast will easier bend in the top
  2. The difference in profile between bottom and top accomdates to the difference in windsheer at boom and top level. There is a built in windsheer compensation as the exit in the top is flatter than in the bottom.
  3. The mast has less drag which leads to higher speeds and more height
  4. The mast is stronger as it is a RDM style mast. Reduced Diameter Masts do break less as the wall thickness is higher than in bigger masts. You see the same trend in windsurfing
There are two disadvantages:
  1. As the mast becomes thinner in the top we have to use more high modulus in the top to make it as stiff as needed. This makes the mast slightly heavier (200 grams).
  2. The mast is a bit more expensive as we have to use more high modulus carbon fiber and because the mast is made in a more expensive mould.
Our base mast is 76-137, which is suitable for most people. We have tested with sails which were made for both the Saarberg and the Fiberfoam masts and these rigs were fast. We do see now that the first sailmakers start to design special sails for it. (Landy , Stevie). The sailmakes can add just a little bit extra luffcurve in the topsection (between batten 3 and four; the powerzone)

Sail development

The membrane sails of Glenn and Landy are the newest trend. These sail hold their shape very well and are clearly faster downwind than most other sails.
The sails are significantly lighter. We still have to see how durable the sails are though.
Another trend is the return of the positive roach on the sails of both Glenn and Stevie. The consequence is slightly smaller heads (in the case of Stevie), but better control of the overall shape with your mainsheet.

The membrane sails are fast downwind because the leech is stiffer than most other sails. The Maxx sails are relative soft in the leech which leads to fast sails upwind but makes it harder to use downwind as you easily pull too hard on yoour mainsheet.  It is not that the Maxx sails are exactly slow downwind, but certainly harder to use.

The Stratis sail of Glenn is very hard to trim upwind as it is more sensitive to mastrotation and cunningham than the sailsof last year. We do see higheer endspeeds though.

The membrane of Landy is claimed to be easier to use and is in essence a second generation membrance sail. I have not used it myself so I cannot comment on its performance.

Stevie has switched to radial sails which seem to be very fast downwind. Center of effort is pretty high up as he uses a high clew and the sail is relatively wide at the hounds. The radial sail is also stiffer in the leech than last year's Maxx and might therefore suit heavier sailors better.

Micky made a very nice Maxx Pentex sail for Chris Field with which he did very well at both the German and the French Championships. Although he uses pretty soft cloth he aligned enough fibers along the leech to have a good downwind performance.

My conclusion is that it makes sense to use stiffer sails on softer masts. This can also be accomplished with traditional sailcoth by changing fiberorienations and/or by using other fibers.

Another prediction: The difference between rigs for the ligher and heavier sailors will become smaller!
Adding more luffcurve for the heavier sailors does not make always sense as it can hurt their endspeeds. If the lighter sailors still can flatten the fuller sails on their masts, they will use the fuller sails as well.
Last two seasons the lighter sailors were way faster downwind, I do think that this will be no longer be the case as the sailors will get more power out the sails downwind and the higher righting moment leads to higher speeds.
The longer daggerboards do help the heavier sailors as well as it seems  to be easier to keep the boat on its boards especially in  rough conditions with waves or big swell.

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