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Lee-Bow..... Windsurfers...etc (Dons tin hat)
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Rupert View Drop Down
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Topic: Lee-Bow..... Windsurfers...etc (Dons tin hat)
    Posted: 27 Sep 19 at 3:24pm
So, as a river sailor, I have often crossed a river when pointing at 45 degrees into the stream whilst, annoyingly, making no forward way. This is similar in its outcome to being tethered, but I'm pretty sure the physics is different. All I'm doing is sailing across a river. If there was no current, I'd have gone forwards and crossed. The current is wiping out my forward motion.
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iGRF View Drop Down
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Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 19 at 7:32pm
Well clearly Rupert you should have gone for Mozzys technique of having the land pull you across.
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L123456 View Drop Down
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Posts: 500 		Post Options Post Options   Quote L123456 Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 19 at 9:56pm
Originally posted by mozzy

Originally posted by iGRF

The Air is the tether. Think of the start line with an adverse current you don't need to cross it before the gun.

So, you either hold onto the start boat (illegal) or you play the rig to maintain station, both tethers of sort.

Ohhh, the old air tether. So you're attached to the land with thin air, i guess using one of those air hook things. 

 
Originally posted by iGRF

Exactly as if you were holding on, what is it with you lot, why can't you understand?

No, not exactly as if you were holding on. In fact, completely different.

If you are using the sails to hold station, then the force to move you through the water is coming from relative movement of air over water. 

If you hold on, then force comes from the relative movement of land and water. The land is pulling you through the water.

I am saying that unless you hold on (tether) to the land, then you cannot experience that force or use that energy. 

So, my question, at the third time of asking, if you are not holding on, or tethered by a rope, or in some way attached to the land, how can you transfer or access the energy from the relative movement of land and water? 

...and don't say using sails and air, because sails and air are not in contact nor transferring forces from the land. 

I admire your efforts but save yourself and give up, I don’t think he believes any of this he’s just baiting you. 
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Hitcher View Drop Down
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Posts: 38 		Post Options Post Options   Quote Hitcher Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 19 at 10:00pm
Originally posted by Sam.Spoons

 http://www.offshore-sailor.com/articles/seamanship/lee-bowing-the-tide/

BUT WHEN THEY BOTH TACK THEN THEY WILL EXPERIENCE THE OPPOSITE EFFECT FROM THE TIDE.  AND END UP IN THE SAME PLACE.

THIS ONLY WORKS IF THERE IS A TIDAL GRADIENT ACROSS THE COURSE. Although sailing the "long tack" first, boat B, is a sensible thing to do.

Are you posting this as an example of articles as recently as 2016 spouting this utter nonsense? Please say you are. Please. I'm begging you.
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 7:21am
Yes that picture ( in the linked article) sums up the problem here. This is why we are 20 pages into this subject and many are still trying to get their head around it. A bit like other whacky pseudo science ( (eg homeopathy-I know the scientists don’t like it but it works for me!)
It surprising that the author doesn’t also point out the additional “benefit” of the lee bow tack of the increased apparent wind! It’s clear in the picture.
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 7:40am
The trouble is there are all sorts of different phenomena that the phrase lee bow gets attached to. The offshore sailor article Sam posted a link to, for example, isn't the lee bow effect that the myth is about, although I agree that it misses the point that what counts is not distance to the mark but vmg.

AFAICS 85% of what GRF posts about tide is perfectly correct, and I'm not sufficiently confident I understand exactly what he means to comment on the last 15%. I'm also not sure that he actually disagrees with the people he thinks he's disagreeing with.
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 8:27am
We have two groups of contributors on this. Those who get it and can’t see what the problem is and those that don't.
A bit like in school those who got quadratic equations and those that didn’t and no matter how much extra home work they never got there.

Anyone who says “it is very complex” doesn’t get it as it is blindingly simple. It’s a left brain 🧠 right brain thing
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L123456 View Drop Down
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Posts: 500 		Post Options Post Options   Quote L123456 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 9:39am
Plus there is a third group, the most dangerous ones ... who think they get it but have absolutely no clue ...
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CT249 View Drop Down
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Posts: 399 		Post Options Post Options   Quote CT249 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 11:04am
It's been said here that the big boat guys are idiots (well, pretty much) and that windsurfers are more sensitive therefore are more likely to feel the (mythical) LBE.

I'm fairly sure that actually the good big boat guys are far more likely to notice the LBE if it existed (which it does not) because they will often have well-calibrated instruments sitting there telling them the boat's VMG through the water, its target VMG, and the actual speed over ground as determined by the GPS as well as other information such as water temp and the predicted course and speed, all of them often monitored by a full time naviguesser.  If the LBE was around, that would be seen by a difference between boatspeed/VMG and SOG (speed over ground) and other data, and in some boats it could come up on the dials and show anyone who was watching - and there's nothing more the crew perched on the rail prefer to watching the dials so they can give "constructive feedback" to the driver.

Windsurfers on the other hand are less likely than dinghies to be locked in a neck-to-neck battle; they accelerate and decelerate faster and there is more difference in speed between comparable sailors than there is in dinghies. If a board climbs out to windward it's more likely to be the sailor hitting the groove better than is the case in dinghies or in yachts, where speeds tend to be more similar. So the windsurfer is probably LESS likely to notice any boost given by the mythical LBE.


Edited by CT249 - 28 Sep 19 at 11:06am
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L123456 View Drop Down
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Posts: 500 		Post Options Post Options   Quote L123456 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 19 at 12:08pm
Originally posted by CT249

It's been said here that the big boat guys are idiots (well, pretty much) and that windsurfers are more sensitive therefore are more likely to feel the (mythical) LBE.

I'm fairly sure that actually the good big boat guys are far more likely to notice the LBE if it existed (which it does not) because they will often have well-calibrated instruments sitting there telling them the boat's VMG through the water, its target VMG, and the actual speed over ground as determined by the GPS as well as other information such as water temp and the predicted course and speed, all of them often monitored by a full time naviguesser.  If the LBE was around, that would be seen by a difference between boatspeed/VMG and SOG (speed over ground) and other data, and in some boats it could come up on the dials and show anyone who was watching - and there's nothing more the crew perched on the rail prefer to watching the dials so they can give "constructive feedback" to the driver.

Windsurfers on the other hand are less likely than dinghies to be locked in a neck-to-neck battle; they accelerate and decelerate faster and there is more difference in speed between comparable sailors than there is in dinghies. If a board climbs out to windward it's more likely to be the sailor hitting the groove better than is the case in dinghies or in yachts, where speeds tend to be more similar. So the windsurfer is probably LESS likely to notice any boost given by the mythical LBE.

Don’t come here spouting your common sense and logical argument. 
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