LEE BOW EFFECT

In the meanwhile I've had another look at Eric Twinames section on tide, he does deal with it, but he also misses the essential part of the tidal equation, which maybe back in those days wasn't as relevant and probably because the stuff we sail amplifies the effect (Literally a favourable tide in certain conditions can make the difference between planing up wind and displacement speed).

Originally posted by Peaky   That is the fallacy. The orientation of the boat's hull does not affect the direction it gets "pushed" by the current.

It depends on the angles. As soon as there is any component of the tide against the wind, you will get lifted. Basically means difference between tide and wind needs to be greater than 90 degrees and you will get some Lee Bow effect. At least in the definition I know.....

No it doesn't!  The apparent wind is a combination of a moving volume of air (True or Ground wind) and a moving carpet (OK volume but in practice it's 2D) of tide (the tidal wind), and your boat speed and your angle to the wind (I'll call it induced wind).   Pinching or footing changes the induced wind but it can not change the tidal wind.

But we need someone clever to do some vectors!

Originally posted by JimC .... Same term, different meanings... it sounds as if you've never come across the traditional lee bow fallacy. That says that if the tide is more or less bang on the nose you should pinch up so that the tide is fractionally on the lee bow because even though you'll go more slowly the tide will push you up to windward. Its nothing to do with the choice of which tack is favoured and thus which you should be on, which is what I believe you are talking about.

Quite succinctly put, Jim.


One element that messes with your head is the fact that because the boat is slow relative to the ground, the apparent wind does not move forward as you expect it to, therefore you seem to be able to pinch without slowing the boat.
This feels like a strange effect, which some people seem to roll into 'the lee bow magick'
We tend to think in the 'land and marks' frame of reference, whereas the boat is operating in the water frame.