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

OK GRF
so the tide will induce a tidal wind coming from the WSW ( the opposite of the ENE tidal direction. If our friend is pointing north he will then sheet his sails in or a reach. All the boat will experience this light WSW wind and will start to sail where they want to go using this wind. Wind is the same whether its from the general movement of air or from the movement of water that our boat is sitting on.

I wondered how long it would take for the climate change deniers to turn up.

I'm done, believe what you like.

And Gareth, congratulate No 1 son from me and tell him to ignore dinghy sailors when it comes to advice as to how to sail in tide, particularly RS200 crew ;-)

That there is no way to downvote sh*t posts is one thing that's wrong with this forum. 

OK Here goes - my simple explanation for why the LBE is fallacy.

First to get things straight what do I mean by the LBE. (Lee bow effect).
This is the additional advantage that you get from the effect of the tidal flow when it hits the boat (and foils) on the lee bow. This increases the apparent wind and also lifts the boat to windward. This results in greatly improved performance even if it is obtained by "pinching" to obtain it.

Race Scenario 1
The best way to get your head around it is to consider what would happen if we had a race in a strong adverse tidal stream with the course on starboard tack aligned to the tidal flow ( which could just be got onto the lee bow by pinching) where all the marks were free floating. There is uniform tidal strength across the course.

As the marks were free floating ( with sea anchors) unless we looked at the shore line we would not know that we were in a tidal stream. We would experience a wind strength and direction that was a vector sum of the true wind and tidal induced wind, and this would be constant in strength and direction across the course. In this race some boats raced as normal concentrating on boat speed and picking up the minor shifts and others tried to use the LBE by pinching on starboard tack to gain the LBE .
I predict that the boats that pinched on starboard would not be in the lead at the windward mark.

Race Scenario 2
Taking this to the next stage if we now had a race that the buoys were all movable at 3 knots ( think RIBs rather than motorised buoys!). We had the same race with any tide. Would the movement of the marks make any difference to the race. I suggest that they wouldn't.

Race Scenario 3
The next stage is to have a race where we had like race 1 the tide, but we also had like race 2 the buoys moving at a constant speed. This would be just like the result of race 1. This is exactly what we have when we have moored buoys in a tidal stream.

I hope that makes sense. Once you get that the rest drops away.

The fact is if you were to oversheet to that degree without an additional reason for doing it, (getting the tide on the lee side of the foil) you would simply stall out and slip behind. That technique was two fold, back then there were no cambers which tend to control the angle of attack of the rig. The rig in fact was a dinghy style rig, a needle spar mast and possibly a Mountifield (local sail builder)sail. Pressure is applied to the back of the board as well as oversheeting to get the foil across the flow and you'll have to trust me when I say it doesn't work, certainly not as effectively, without the extra pressure you get from tidal flow. Like it to not, it's true, it works and our sub terrainean friend like so many others are wrong when they refer to tidal flow as only a moving carpet to be ignored. I'd say if you want to win stuff on the sea then ignore the tide at your peril.

Edited by iGRF - 17 Sep 19 at 1:50pm