Lee-Bow..... Windsurfers...etc (Dons tin hat)

Originally posted by iGRF That's funny, it's the first time I've seen you two turkeys active in quite a while..

TBH I can't see a difference, the foil in a board is fixed relative to the hull, sure you can oversheet so the sail stays full at extreme angles more easily than in a boat but it still results in reduced forward drive in exactly the same way as it would in a dinghy. What you can do with a board is engage the rail which reduces leeway and increases the waterline length, both of which will help you to point higher without loss of speed.

First, to answer a few of the questions about my lad’s sailing:

He was on an old (non-batwing) Starboard Phantom Raceboard. He did spent a lot of time on Techno and RS:X, but has only ever pottered on the Raceboard.

The thing he did with his feet: it wasn’t really windy enough to ‘rail’ in the conventional sense, but with one foot over the centreline the other was lifting the front strap to lift the weather rail and dig the leeward rail in (his words “for want of a better term, over railing it”). This in effect gave him a much bigger ‘foil’ in the water. (Clearly, it could be the lift from this foil alone, ignoring any LBE that gave him his upwind escalator). Plus, he says he was pinching so should've lost speed but didn't.

Interesting, both the sailors who made outstanding gains upwind in this race believe (independently) it is because they managed to get the current on their lee bow when others didn’t!

And to address a point from many pages ago, the RYA did coach the ‘lee bow effect’ with the national squad.



I still have an open mind on the whole thing. The ‘conveyor belt’ analogy is just that; a simplified model that stands up as a generalisation but does seem to assume that water is not viscose, a steady state has been found, and possibly no other forces are acting.

If we can agree that the Hampton Loade ferry works due to the current flowing over a foil and the force applied on the boat via the rope, and can also agree that a resultant force is just a vector regardless of what it is applied by (be it from a rope across a river, an anchor, or a sail), then does it not follow that there may be some circumstances in which the effect experienced by the ferry could also be experienced by a sailing craft?

Okay, it may well be that the effect is so negligible compared to everything else going on that it can to all intents and purposes be ignored, but that does not mean it isn’t there.

My feeling is that if it is exploitable it would be very nuanced. From the time I’ve spent with some very good windsurfers (being a dinghy grunt myself) I know that feel is much more of a ‘thing’ to them. For example, dinghy foilers rely on mechanical systems to control their ride, whereas my lad will be subtly tilting his head to vary the weight distribution to control his foil angles. If there is a very small effect to be exploited, I can believe that (very good) windsurfers could feel it whilst a heavier slower dinghy with with far less direct feedback (e.g. through a tiller, multi-purchase mainsheet, sat on your backside, etc, rather than direct to body) may not.

But maybe it is more fun just to call GRF a dick than keep an open mind.


Edited by GarethT - 26 Sep 19 at 7:46am

Nice post Gareth t
Their are current ferries around the world that transport cars and hgv's, so must be able to apply significant force.