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Search took 0.00 seconds. Search: Posts Made By: Dockhead

Forum: Challenges

22-11-2013, 12:18

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I can only add to that, that the most important thing for these problems is total tacking angle, which includes leeway, true-to-apparent conversion, etc.

However, it is very important not to...

Forum: Challenges

22-11-2013, 06:36

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

No one disagrees. In fact, there are situations...

No one disagrees. In fact, there are situations where you can lay your mark without even sailing - just drift to it. This is all completely irrelevant.

Forum: Challenges

22-11-2013, 06:34

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

So does it fit the given thesis? Word for word...

So does it fit the given thesis? Word for word :"you can't lay it"

I did NOT write "you couldn't lay it but for the current". A very different thesis. I also did not write "your destination...

Forum: Challenges

22-11-2013, 04:33

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

LOL, you are persistent! :). Come get your...

LOL, you are persistent! :). Come get your Champagne already and leave me alone!:) :) :)

But there is not even a minor technicality. I specifically defined "upwind mark" as "one which cannot be...

Forum: Challenges

22-11-2013, 03:26

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

The champagne is yours in any case, but your scenario is not included in the problem I posed. "Directly upwind" from ground perspective is certainly not going to be directly upwind in water...

Forum: Challenges

22-11-2013, 02:45

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

My darling, I can find a bottle of Mumms for you any time :)

But no, if you can lay the CTS without tacking, then this is not an "upwind mark" for purposes of this problem. By definition of the...

Forum: Challenges

21-11-2013, 17:26

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Sorry, I'm just getting back up to speed having been buried in work the last couple of days.

There is a lot of argument in here about the frame of reference. In fact, of course, there is no...

Forum: Challenges

19-11-2013, 06:59

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I suspected this confusion, and now I'm absolutely sure of it.

Look here --

A non-changing current has no affect on the wind whatsoever. It changes one ground wind to another true wind. But...

Forum: Challenges

19-11-2013, 06:30

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Yes, but you are stating a navigation problem, not a sailing problem.

If the current is not changing, it's irrelevant to sailing, but not irrelevant to navigation. If the current is not...

Forum: Challenges

19-11-2013, 05:44

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I don't understand any of this.

In a steady current, there can't be any Effect of any kind -- you've got one true wind, and you sail as usual in it. No effects of any kind. Just because a current...

Forum: Challenges

19-11-2013, 05:40

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

LOL :)

In our perverted parlance :), a "knock" is the opposite of a "lift". It's any change in the environment which worsens your situation. When speaking specifically about wind shifts, yes,...

Forum: Challenges

19-11-2013, 05:19

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

As to "knock", by the way --

I've got nothing at all against "header" and "headed", of course.

But "knock" is proper racing terminology, at least in Yankeeland. You would have an argument,...

Forum: Challenges

19-11-2013, 05:15

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

OK, so if there is no abrupt, magical transition at the bow, when the current goes from slightly on the windward side to slightly on the lee side, then how can it ever be worth the lost VMG to...

Forum: Challenges

19-11-2013, 03:14

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

When you say "the effect of pinching is reduced if you . . . come up slightly to windward" -- what exactly do you mean?

What effect occurs in a few degrees from dead on the bow to slightly to...

Forum: Challenges

19-11-2013, 01:57

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

You get an "A" for effort, or full marks as you guys say over there. Keep poking away at it and you can understand anything. You are not thick.

I'll give you some hints:

When you are on a...

Forum: Challenges

19-11-2013, 01:44

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Exactly. This is a different flavor of Lee Bow Effect than what we have been discussing lately. This is the "if you can pinch to get the current from fine on the weather bow to fine on the lee bow,...

Forum: Challenges

18-11-2013, 07:41

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Yes, now understanding it much more deeply,...

Yes, now understanding it much more deeply, thanks to this thread and everyone who contributed, I would not just keep the current on the lee bow. I would work up the problem, starting with CTS...

Forum: Challenges

18-11-2013, 00:47

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Interesting question --

Some Channel sailors believe that the LBE works because it shortens your distance sailed over ground. This is obvious nonsense, and it threw me off -- that's why when we...

Forum: Challenges

18-11-2013, 00:43

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Look, think about it like this:

No current, zero boat speed -- zero forces.

10 knots of current, zero boat speed -- zero forces - identical.

No current, 6 knots of boat speed -- certain...

Forum: Challenges

17-11-2013, 17:23

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

The key word here is apparent water flow. You've almost got it :thumb: Everything you write is true; you just have the wrong frame of reference. It's the water -- apparent water flow, as you wrote....

Forum: Challenges

17-11-2013, 15:49

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

And we slouch towards total consensus :thumb:

What a great thread. I wish I had time to make a YM article out of it.

Forum: Challenges

17-11-2013, 14:59

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

I do not disagree! :flowers:

I don't want to take anything away from your excellent work.

The most excellent thing about it is that you have proved that the Effect is not caused by the...

Forum: Challenges

17-11-2013, 14:35

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

The point was explained somewhere above. The...

The point was explained somewhere above. The Effect is useful somewhere around current=perpendicular to ground wind. Somewhere around current=parallel ground wind, the Effect does not exist.

So...

Forum: Challenges

17-11-2013, 14:32

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Leeway is included in the tacking angle. Boat...

Leeway is included in the tacking angle. Boat tacks through 90 degrees over ground, for example - includes apparent to true and leeway.

Forum: Challenges

17-11-2013, 13:52

Replies: 774

Let's Get to the Bottom of the Lee-Bow Effect Once and For All

Views: 57,001

Posted By Dockhead

Re: Let's Get to the Bottom of the Lee-Bow Effect Once and For All

You have a great talent for visualizing these problems in drawings :thumb:

But unless I'm missing something, your drawing exactly proves my point. The yellow parts on your drawing are all...

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