Jib question

Sails, sails, sails... A sailboat is not just sails, it is sails plus boat. There is an underwater part of it at work too.
I agree that at this point only a test boat can tell the truth.

 

Daiquiri,

Point well taken, you just usually have nothing you can do with the hull while sailing, and little with the board and rudder, compared to the sails.

So should we move the dagger board/ centerboard off center also? Sort of like H'ydroptere? Sorry that was a poor joke.

 

That is the whole point. Well done

Upchurch ( not Daiquiri - my typing error )

Your statement
", I have never seen a sailboat with either of those diagrams, assuming the wind is from the top."

is very strange


Position A is what the WHOLE DISCUSSION is about - moving the leading edge of the Jib to leeward !!!


Position B is what EVERY MONOHULL SAILOR IN THE WORLD has done -

its what occurs when you BACK the Jib while tacking.

I assert at the top of my lungs, that there is no effective difference in those two sail positions. Some poor people are trying to say that you will point higher with that configuration.

I say that every sailor in the world has tried that configuration and knows that it does nothing of the sort.

 

rwatson

Thanks for the illustration.
I never imagined anyone was talking about something that made no possible sense.
True your right hand picture is used on less than wonderful boats to make a tack, but almost no one tries to continue sailing in this configuration, so I never dreamed that was your argument.

Just so I can show what I believe we should be talking about.

https://lh3.googleusercontent.com/-...AAAqg/cYwI_6usbmw/s912/Jib%20to%20Leeward.jpg

It would be more feasible on a multihull.

Marc

 

Its good my intent came through.

I understand your diagram, but it isn't what started the discussion

Here is the original statement

"Every degree of angle you swing the jib tack to leeward, as measured from the jib tack to the mast, you gain that number of degrees to windward."

That isn't what your diagram is as I understand the proposition.

 

Rwatson,

These threads drift a bit. Sometimes its a good thing.
I never believed the initial statement, but the basic idea is still interesting.

What are you interested in?
Nit picking a statement you don't believe, or moving on to something that might work?

 

Basically, I was trying to come up with a practical concept to explain all the good vector diagrams, that have been submitted explaining why it wouldn't work.

Mikkos comment "No offence, but I find this thread kind of depressing. To me it suggest that so many of all the amateur and semi-pro boat designers on the forum fail to understand how the sailboat really works. There is no magic in how the sailboat works, and there is no way violating the drag angle rule," was indicative of the kind of confusion that was arising.

The reality that moving the clew to windward was the same as moving the tack to leeward for this exercise took a while to dawn on me, and then actual experience that all sailors get was the easy way to prove the point.

I hope it is helpful.

On re-reading some of your earlier posts, its easier to see where you were coming from. I was concentrating on the basic premise.

 

OK, it isn't what was originally claimed by Eric. But what do you think this configuration is doing for you? Does it look to you like there is any "additional lift", or the drive is at any different angle than if the sail was in the on-centerline position?

By the way, my boat used to have exactly the configuration you have drawn. It did not make the boat point higher, nor did it give more lift. It was simply used to allow an overlapping headsail to sheet corrrectly around a long spreader rig that was not meant to have overlapping headsails.

 

How do you know that? I mean if you moved the jib bcs it was the only way to set it in the first place so how you know..

 

Because the boat in both modes had jibs. The boat would be fully powered up with the genoa in about 6 knots of wind, overpowered in about 8, so anything more than that we used a jib, same as I use now.

The question is, why does anyone think the sliding tack sailplan in the sketch is going to point higher than the one on cl?

 

Another jib.. not the same.. hardly conclusive but now the votes are 2 to 1 of real life testing..

 

with many years working in aerodynamics in an earlier life, I would speculate that moving the jib to windward likely greatly improves the flow over the main sail, keeping the flow attached and prevent it from stalling, allowing for a higher angle.

 

Sorry, but I don't see any other "real life testing" on this thread showing a sliding tack makes a boat point higher or more powerful when sailing upwind.

Eric's original claim has been debunked. He said he had done it, but then backed off that claim. He has not had the decency to clarify this, so some people still seem to believe it.

Then someone else claimed Eric had used it in a race and it was proven. But I sure don't see any evidence of that. They were just parroting his claim.

Then there are some comments about beam reaching on multihills, but that has nothing to do with the subject.

So can you point me to the real life testing that shows us that dropping the tack to leeward improves pointing, or adds power?

 

Petros
That's excactly opposite what's been discussed here. Doesn' t work with soft sails and with wings thou the lift increases it increases also the drag even more drasticly.

 

I don't give much credit to any of the experiences mentioned here. None of the them proofs nothing so they are only "votes" so far..

But... Interesting is what I find it as a question. And quite funny how most of the "pros" are staying out of the conversation, just maybe too afraid to being wrong, whatever is right. Anyway I've told what I think makes it tick, if it ticks and waiting for some intelligent response...