New Posts New Posts RSS Feed: LEE BOW EFFECT
  FAQ FAQ  Forum Search   Register Register  Login Login

LEE BOW EFFECT
 Post Reply Post Reply Page  <1 1011121314 22>
Author
  Share Topic Share Topic  Topic Search Topic Search  Topic Options Topic Options
JimC View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 17 May 04
Location: United Kingdom
Online Status: Offline
Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Topic: LEE BOW EFFECT
    Posted: 15 Oct 11 at 12:35am
Originally posted by G.R.F.

We're not discussing the 'pinching issue' the OP didn't ask that,

Well some are, some aren't. There are at least three phenomena people use the phrase "lee bow" for... The pinching thing used to be widely described - page 39 of the edition I have of Proctor's "Sailing, Wind and Current" from the early 60s for example. Maybe the board sailors were too smart to fall for that one so you never came across it. You do still come across it from time to time amongst those who haven't spent enough time learning about developments in the sport since the sixties.

From the OP description there's no way of telling which phenomenum he's had described to him. That the tide is more favourable when on the lee bow is perfectly true, of course its even better when on the lee stern [grin]. The more you can keep the current on the favoured side then, normally the better you will do, the main exception being when wind and current shifts are favoring opposite tacks and the peculiar adverse current *downwind* situation ILuvWight describes...
Back to Top
G.R.F. View Drop Down
Really should get out more
Really should get out more


Joined: 10 Aug 08
Location: United Kingdom
Online Status: Offline
Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 15 Oct 11 at 1:41am
Originally posted by Ian29937

 
So how do you use this mythical beast if you don't sail higher than the other boats about you.  If everyone sails at the same angle to the wind and tide they either all get a lee bow effect or they don't.

It's not wether two of you doing the same thing do it better or worse than each other, it's wether one knows it's even happening or not and or believes it to be beneficial.


Originally posted by Ian29937

 
You're changing the question, discussing the use of tactics with tidal bends now, (and in your example, you are as likely to lose out as gain by taking the high risk option which would disprove your theory in any case). 
 
We are talking about a specific boat on boat situation - if I can get a lee bow when others around me don't, do I gain an advantage ?  No....
 
Ian

Er yes, especially when the other sailors have been briefed as half this forum is briefing in that it doesn't work.

I'll return to a specific example, many years ago i was asked to do a tactics lecture to the Olympic youth squad, by the then coach, half way through my lecture on tides, he very rudely and publicly disagreed with me in similar vein to some here, and cut the lecture short. In his day he'd also been a fair sailor, but never a tactician and never my level, so I was naturally not that happy.

Some 4 or 5 years later I'd been participating casually in the last day of the nationals at which the fleet had been sailing in disadvantageous tide and there were cliffs inshore that mean a lift on the way back out, bit of a wind bend, so first into the cliffs riding the knock and escaping the tide was first out, so a pretty mundane course.
Anyway the last day saw the same conditions with a tide still strong out to sea only this time the wind had backed a bit further out to sea and the course was a long distance event round an island and back. I wasn't going to bother, until I saw and overheard said coach lecturing Britains finest and pointing out all the same stuff on his course board sketches, into the cliffs, miss the tide go along the coast enough distance before striking out to sea taking the lift off the cliffs to help against the negative tide they'd take crossing the tidal flow into the bay. I saw something different.

Mine involved going exactly the opposite side of the course to some other cliffs on the other side of the bay, then flacking over and making the crossing with the tide on the lee bow.

So I'm at the windward mark, by the island, ten minutes clear of the entire fleet, having a little chat with my Olympic coach colleague and his team, about not interrupting my tide lectures in future, and pointing out that his Boys and Girls were still mere specs on the horizon and next time a)don't be so rude and b)pay a bit of attention and he might learn something.

They've never asked me since, it doesn't do for Olympic coaches to be shown wanting.

So that's an extreme example, but in answer to others around me, had there been that many (there was one who followed but he didn't quite stuff it high enough to make the effect stick, and it was one of those situations where the higher you got, the easier it was to make it stick, to the point it got so good i free'd right off and went for speed. So yes, if you spot it get an advantage and it improves where the other guy didn't then yes. But you have to a) spot it and that involves reading the water, and b) have the confidence of knowing it will work, both of which come with experience of sailing lots of different tidal venues over lots of years.

Finally, it's a lot easier on a board, because you're standing and see more than when you're sat in a dinghy and you feel it directly through the boom the rig feels more powerful the moment the lee bow cuts in and you can stuff a board by over sheeting and or angling the board higher than the rig, kind of manually gybing the centreboard in order to get the flow pressure the other side of the foil.

Jeez I think i've written enough now, almost an article in its own right, I'll work on those drawings and try and remember all the tactical scenarios I used to illustrate and what to do in various circumstances to even the odds in your favour, but it won't get done overnight.




Edited by G.R.F. - 15 Oct 11 at 1:48am
https://www.ease-distribution.com/
Back to Top
2547 View Drop Down
Really should get out more
Really should get out more


Joined: 11 Aug 11
Online Status: Offline
Posts: 1151 		Post Options Post Options   Quote 2547 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 11:13am
Originally posted by G.R.F.

Originally posted by Presuming Ed

Next you'll be saying that you can sail in a 3kt easterly with a tide setting 3 kts to the west....
A frequent occurrence where I sail...


I think that is enough to confirm the need for these

Originally posted by Presuming Ed

By the sounds of it, he's advocating using a perpetual motion machine...


Indeed ...
Back to Top
bert View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 23 Apr 05
Location: norwich usually
Online Status: Offline
Posts: 584 		Post Options Post Options   Quote bert Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 11:23am
I for one look forward the "drawings and try and remember all the tactical scenarios I used to illustrate and what to do in various circumstances to even the odds in your favour, but it won't get done overnight."
& thank you GRF if you can do for me / us -- no piss take I would geninely like to understand this better.


Edited by bert - 17 Oct 11 at 11:23am
Phantom 1181
AC-227 IC 304
blaze / halo 586


Back to Top
2547 View Drop Down
Really should get out more
Really should get out more


Joined: 11 Aug 11
Online Status: Offline
Posts: 1151 		Post Options Post Options   Quote 2547 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 11:43am
Originally posted by bert

I for one look forward the "drawings and try and remember all the tactical scenarios I used to illustrate and what to do in various circumstances to even the odds in your favour, but it won't get done overnight."
& thank you GRF if you can do for me / us -- no piss take I would geninely like to understand this better.


Bert ... if you really want to understand then buy a book from a bloke who has won loads of championships and has coached at the highest levels ...

http://www.amazon.co.uk/RYA-Tactics-Mark-Rushall/dp/1905104219

.... but GRPs etchings would no doubt be good for a laugh.
Back to Top
Ian29937 View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 25 May 05
Online Status: Offline
Posts: 409 		Post Options Post Options   Quote Ian29937 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 12:28pm
Originally posted by JimC

Originally posted by G.R.F.

We're not discussing the 'pinching issue' the OP didn't ask that,

Well some are, some aren't. There are at least three phenomena people use the phrase "lee bow" for... The pinching thing used to be widely described
 
Thank you for that.  I've been focussing on the boat on boat 'pinching' effect as the other two, (which I presume are the bigger picture tidal effect which relies on boat separation, and the wind effect caused by a boat which is very close to leeward ) are well documented and understood and are not in any way controversional.
 
Ian
 
btw In terms of the big picture tidal tactics grf is now focussing on, I can easily imagine where a windward bow effect could also be beneficial, when trying to soak down to a mark in light airs for instance.  BUt it always depends on getting enough separation from the oposition to be in a different tidal effect..
Back to Top
G.R.F. View Drop Down
Really should get out more
Really should get out more


Joined: 10 Aug 08
Location: United Kingdom
Online Status: Offline
Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 12:46pm
I've just thought of a definite scenario when "pinching' in a tidal lee bow situation will be beneficial.

If there are two boats about even on the same tack, both in a tidal lee bow situation, then if the leeward of the two, pinches and establishes a lee bow overlap, i.e. gets his nose ahead of the windward boat but points high enough to establish a 'lee bow' header by distortion of the flow over the windward boats jib or main if its a single hander, then it will gain an advantage over that boat.

No question, no doubt.  Another example of Lee Bow and it's application at work.

So now David Perry where is he now?



Edited by G.R.F. - 17 Oct 11 at 12:47pm
https://www.ease-distribution.com/
Back to Top
G.R.F. View Drop Down
Really should get out more
Really should get out more


Joined: 10 Aug 08
Location: United Kingdom
Online Status: Offline
Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 12:48pm
Originally posted by seamonkey

 a bloke who has won loads of championships and has coached at the highest levels ...


That would be me then.. LOL
https://www.ease-distribution.com/
Back to Top
JimC View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 17 May 04
Location: United Kingdom
Online Status: Offline
Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 1:00pm
Originally posted by G.R.F.

So now David Perry where is he now?

Still talking about something different...

Carry on with the stuff about tactical options in tide though: fascinating and something I know stuff all very little about...


Edited by JimC - 17 Oct 11 at 2:54pm
Back to Top
Presuming Ed View Drop Down
Really should get out more
Really should get out more


Joined: 26 Feb 05
Location: United Kingdom
Online Status: Offline
Posts: 641 		Post Options Post Options   Quote Presuming Ed Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 11 at 1:54pm
Originally posted by G.R.F.

 If there are two boats about even on the same tack, both in a tidal lee bow situation, then if the leeward of the two, pinches and establishes a lee bow overlap, i.e. gets his nose ahead of the windward boat but points high enough to establish a 'lee bow' header by distortion of the flow over the windward boats jib or main if its a single hander, then it will gain an advantage over that boat.

Why on earth does the tide make a difference? If you can go into point mode and gain a lee bow position on a boat to windward, how does the tide have any affect on this? Why could you not do the same with the tide from astern, or no tide at all?

Or does point mode cease to exist as soon as you cross the coast and start sailing on ponds? 
Back to Top
 Post Reply Post Reply Page  <1 1011121314 22>

Forum Jump Forum Permissions View Drop Down

Bulletin Board Software by Web Wiz Forums® version 9.665y
Copyright ©2001-2010 Web Wiz
Change your personal settings, or read our privacy policy