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bert View Drop Down
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    Posted: 19 Oct 11 at 11:54am
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.
 
Would you consider doing this,If you could find the tactial stuff & illustions that would be great.
This back & forth posting is just confusing & in danger of becoming a worthless thread when it could be a great benifit to a lot of people if it was explained well.
 
Thank you 
 
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Oatsandbeans View Drop Down
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 12:26pm
GRF -I don't want to get involved in a slanging match but I just like to deal with the points that you have raised. 
First, I am not a " full time coach", I race dinghies most weekends and spend some time helping the young kids at the club. Where I sail is very tidal with 3 1/2 knots on springs, so I do have a lot of practical experience racing in strong tides.  I have also done, in my youth, a lot of international dinghy events so I have a depth of knowledge on dinghy racing tactics. 

My position on this is that until 1982 I fully believed in the Lee Bow effect and could vouch for numerous situations where it worked in my favour. In a discussion with one of my competitors I was astounded when he stated that there was no lee bow effect. He then explained it to me and he convinced me that I had been wrong, ( that sailor was Steve Goacher). I now have a simple explanation of the effect (or lack of it!) that I do for anyone that is confused on the matter! So if anyone wants I can do this on this thread, (but I suspect it has been done to death anyway)

PS I even remember racing against you in IMCO in the 80's
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G.R.F. View Drop Down
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Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 12:44pm
I made a start on some of the illustrations last night, got myself an iPad app, but it takes ages and there are so many bloody variables, I feel a bit silly doing it really as I'm sure it must have been done before by sailing minds far more experienced in boats than me, I'm sure somewhere there must be a book on the subject.

It's a big deal, or it used to be. I did the basic components in a rough sketch for that sea monkey girl, which helps the understanding I guess, I'll bung what I've got up here in a minute, but to really illustrate what happens at various speeds would take hours..

My old notes and records got lost in a house move twenty years ago, which is a shame, because I'd documented the tide variations in the various courses and venues I'd sailed during my fifteen minutes of fame and glory and I had done it precisely because my memory was never totally reliable, one coastal tide bend easily gets confused with another.. Not for one moment would any of those venues be anything like the way they were then as the bottom shifts all the time, but the examples would have helped illustrate the point.
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Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 1:03pm
Originally posted by Oatsandbeans

GRF -I don't want to get involved in a slanging match but I just like to deal with the points that you have raised. 
First, I am not a " full time coach", I race dinghies most weekends and spend some time helping the young kids at the club. Where I sail is very tidal with 3 1/2 knots on springs, so I do have a lot of practical experience racing in strong tides.  I have also done, in my youth, a lot of international dinghy events so I have a depth of knowledge on dinghy racing tactics. 

My position on this is that until 1982 I fully believed in the Lee Bow effect and could vouch for numerous situations where it worked in my favour. In a discussion with one of my competitors I was astounded when he stated that there was no lee bow effect. He then explained it to me and he convinced me that I had been wrong, ( that sailor was Steve Goacher). I now have a simple explanation of the effect (or lack of it!) that I do for anyone that is confused on the matter! So if anyone wants I can do this on this thread, (but I suspect it has been done to death anyway)

PS I even remember racing against you in IMCO in the 80's

Yes, apologies for coming across as harsh as that, everyone has a right to their opinion and we all have our beliefs, I'm sorry, don't mean to offend you.

I'm intrigued as to how 'that sailor Steve Goacher' managed to convince you that what you must have been convinced about and experienced 1st hand on numerous occasions, doesn't actually exist, or was he another Perry?
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 2:55pm
Well I don't know anything about Perry but I was convinced by Steve by his explanation, and I now try to summarise it.

The only effect that the tide has on the wind that is experienced by the boat, is that of the vector sum of the true wind and the tidal effect wind.

The boat and sails behave in an identical manner to this combined true and tidal effect wind as they would to a normal wind without any tide.

So all the rules that apply to VMG (whether to point or foot off) without any tide will be identical to those with a wind modifiied by a tidal effect. ( This means that pinching to get a lee bow effect is pointless as the boat should be sailed as normal to maximise VMG) 

However the tide will have the effect of moving all the fixed points (buoys) and thus there may well be times where it is advantageous to sail differently to accomodate this. For example if you round the leeward mark and find that you are pointing directly into a fast flowing tidal current making little headway. Here it makes no sense to sit there and wait for the fleet to sail up to you. If you can sail off (free off ) and into a weaker tidal stream you can then harden up and make an improved VMG to the mark. This is often difficult as when you free off it intially appears that you go backwards and sideways, but when you hit the weaker tide it pays off as the others spendall afternoon sitting in the tide going nowhere (fast!).

Steve convinced me because he was ( and still is, based on his continuing sucess in the F15), a very good sailor and also quite scientific and analtyical about his sailing ( he took physics at Durham), so I listened to him, and you can't argue with the science.

What concerns me now is, what else have I got wrong in my understanding of this sport, if I was so convinced that the Lee bow effect was a winner -what other dodgy theories do I still base my sailing strategy on that are wrong?
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Posts: 978 		Post Options Post Options   Quote rogue Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 2:55pm
I tend to judge things by my own experience, and I'm afraid to say, my basic understanding of what lee bow tide was/is has been born out several times on the race course.

I think we're all sailing faster boats these days and maybe this means lee bow is less of an issue, but back then, when I took it for granted that I sailed on some proper water, I was sailing Oppies, Toppers and kneewrecking sh*tboxes and in the estuaries I sailed in, I certainly felt the positive effects of leebow.

Edited by rogue - 19 Oct 11 at 2:57pm
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G.R.F. View Drop Down
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Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 3:46pm
Originally posted by Oatsandbeans



So all the rules that apply to VMG (whether to point or foot off) without any tide will be identical to those with a wind modifiied by a tidal effect. ( This means that pinching to get a lee bow effect is pointless as the boat should be sailed as normal to maximise VMG) 


Yes, the thing is, and I think we may be confusing all around us here.

It's not the discussion wether to pinch or not, it's the what happens when you put the tide on the lee bow.

It may be in fast planing hulls, that by pinching they drop off the plane and will not get any more ground from the tidal benefit.

Against slow displacement hulls of yore, which a bloody load of y'all are still sailing, which actually lose little relative speed by pointing higher and will gain ground by tidal assistance, what you lose by pointing gets replaced by addition to true wind speed.

This at that cusp between tide on the nose and on the lee bow.

Those sketches I had done so far and gotten bored with...


In item 1, just a reminder of the normal contributing forces that combine, True Wind and Created Wind for those that may have forgotten

Sketch 2 Shows the (approximate) effect by hardening up the angle narrows, the created wind is less as the boat slows so the apparent wind moves aft.

Sketch 3 Ads tidal flow to the equation this has the effect of strengthening the True Wind, which then in turn speeds the created wind over the water but not over the ground, so still not as fast as in still water, but the true wind element is greater, therefore the apparent wind moves aft so a lift is produced.

Sketch 4 Simply shows that as in normal water the boat can free off and sail faster, or sail high, no different to any other boat on the same tack, but greater than boats on the opposite tack.


Where the crux of disagreement appears to be is a sketch I have yet to illustrate with tide on the nose and the margin and type of boat that may or may not take advantage by heading up enough to gain a lee bow without losing more way than it gains.

Anyway those sketches were aimed at the sea monkey girl to show what the terms meant, there are folk reading this that haven't actually understood a lot of it, then there are those that are beyond expert that attempt to baffle others by suggesting circumstances where it might not work and there are plenty of them, but to suggest the whole thing doesn't work simply for effect when we all know it does, baffles me.
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G.R.F. View Drop Down
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Posts: 4028 		Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 4:07pm
ER F15?

Are you talking about Flying Fifteens?

Flying Fifteens with keels, that don't go anywhere near tidal situations because there are no jettys with colostomy disposal points.

I doubt anyone sailing a flying fifteen would even notice wether he was in a tidal lee bow situation or not unless some elderly butler served notice of it with his morning copy of the Times, freshly ironed.

Seriously nobody in the Flying Fifteen fleet would have the first idea, they're based at Grafham aren't they?


Edited by G.R.F. - 19 Oct 11 at 4:08pm
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Posts: 2899 		Post Options Post Options   Quote alstorer Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 4:37pm
There's big fleets of them on the sea. First time I saw any racing was having a fleet bearing down on my class in Poole harbour (which has very complex tides), the world championships were at Hayling etc.
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 11 at 7:00pm
GRF thanks for the intertesting comments on the Flying 15 class. But seriuosly tidal effects are greater on slower boats and I'm sure that a F15 is a lot slower than anything that you sail -so they must know a thing about tides. ( Steve was sailing 470s and Fireballs in the early 80's)
Thanks for the drawings -I liked them, but they didn't really help much. The main problem with you is that you are still thinking of the tide under your lee bow and what it is doing to your boat- this is not usefull. It only confuses things. The tide is not under your lee bow (doing anything magical) the only 2 things that the tide is doing is 1. modifying the wind that your sails are seeing and 2. moving the buoys around in the body of water that you are sailing in. Until you can understand, or just accept this, you will have a problem with this and you will have real mental problems when trying to sort out what to do on the race course.  The beauty of my approach (apart from being right, of course) is that tidal tactics become really simple. Good luck.
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