Another little conundrum for the hive mind..

Well, I've switched my little EPS to rear sheeting, and done away with all that silly rope in the middle of the boat nonsense back to the way life was in my first ever single hander the Blaze, with a neat little auto block from Ronstan right up the front near the mast and everything is now cool, except I shall have to learn another tacking technique which doesn't involve teeth, but that's not my problem.

My problem is as follows, one fundamental in windsurfing is that you sheet into the centreline and slam the foot of the sail as far back down on the boards as possible to go upwind, which was my secondary goal with this sheeting method. I've even fitted an adjustable forestay to further emulate it.

But...

It doesn't work, the boat goes slower, why is this? Is my question for speculation, why is it Laser style boats don't work centre sheeted?



Edited by iGRF - 06 Jan 13 at 7:40pm

You have switched it TO rear sheeting?

Originally posted by JP233 You have switched it TO rear sheeting?

Yes it was centre sheeted.

Graeme, if you can sheet out and keep the sail filling it will always be quicker than oversheeting. Its basic physics. If you look at the force vectors from the mainsail if it is over sheeting you will have virtually no forward component, only sideways and therefore slow.
The roller on laser tillers does indeed allow the traveller to be tightened right down but this is not to prevent the boom moving out to the quarter, it is to allow the leech tension to be maintained against the rather bendy mast. Even with the super tight traveller the boom on a laser is over the rear quarter when fully sheeted in. In most single sail classes this tends to be a good approximation for the best upwind position.
As has been said on two sail boats you can drag the main up to the centreline but only because the flow angle onto the mainsail is altered, and most of the forward drive is developed by the jib.

The other thing to remember is that in light airs you need to sail free to maintain attached flow. Dinghy sails tend to collapse and therefore struggle to re-attach whereas more rigid windsurfing sails can quickly re-attach the flow. The other thing is that with light winds there tends to be a very thin boundary layer therefore there is a large pressure and directional gradient acting on the rig, so you want to allow a fair amount of twist in the rig. As the wind speed picks up to 7-8kts the boundary layer gradient over the height of the rig will be less and therefore you want a tighter leech.

There are other reasons such as rotational centre of effort of boards vs dinghies, and position of foils which will also dictate rig set up.

From what you have said, I would say you were oversheeted and pointing too high. If you compared your actual track across the ground I would imagine that even though you outpointed other boats on the lake they probably sailed a higher course???

yes yea ...single sail set-up .... about 30-35cm from centreline works best for the Blaze in terms of VMG and I suspect  the EPS is not that much different.  Tighter can work in a tactical sh*t-fight with a real pain in 'the whatsit' in his or her 'pinch and fight' traditional box but long term all around the course a bit lower works best for boat speed ... and handicap.

But you might have known this already ....

Mike L.