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Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Topic: Weight equalisation
    Posted: 03 Jan 22 at 10:28am
Griff, if you didn't have a trapeze you couldn't have your feet on side of boat and lie out horizontally, you would have to put your feet under hiking straps, but because you are nearer centre line of boat you have less righting.
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Post Options Post Options   Quote mongrel Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 12:15pm
Originally posted by iGRF

Originally posted by 423zero

Think about the angle the wire is from your body to the mast, it's not much off vertical, if you stood at the side of your boat and tried to tip boat on its side using the exact same angle, you wouldn't tip it over.
Youve just made the case for me. Exactly why moving the wire further away helps pull the boat over.

& why in a lull you bend your knees to reduce your righting moment.
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 12:58pm
Originally posted by mongrel


Originally posted by iGRF

Originally posted by 423zero

Think about the angle the wire is from your body to the mast, it's not much off vertical, if you stood at the side of your boat and tried to tip boat on its side using the exact same angle, you wouldn't tip it over.
Youve just made the case for me. Exactly why moving the wire further away helps pull the boat over.

& why in a lull you bend your knees to reduce your righting moment.


And why you'd have to bend your knees further and earlier with a higher hook?

Edited by iGRF - 03 Jan 22 at 12:58pm
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 1:21pm
Originally posted by Do Different

I have a friend who is an engineer. He once told me that he spent half a night in a pub with a bloke who was convinced putting a wind turbine on his car to generate electricity as he drove along could feed an auxiliary motor to save petrol.   
Nuff said.

I'm guessing this is something to do with the 'apparent wind' effect we know and love.
 



Edited by Sam.Spoons - 03 Jan 22 at 1:31pm
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 1:30pm
Tall people have more righting moment not because the trap hook is further from the boat but because their CoG is further from the boat. Moving the hook doesn't change that.

How high up the mast the wire attaches (almost always at the hounds IME) is also irrelevant WRT righting moment but the lower it is the more load on your legs to stay standing horizontally off the side of the boat

You have to have the trap hook at or slightly (but only slightly)* above your CoG to be able to move around the boat, if it's too far above and you feet slip off the gunnel your legs will fall in the water, if to low your head/body will fall into the water.

* In practice slightly above your CoG has proven to be most efficient.


Edited by Sam.Spoons - 03 Jan 22 at 1:31pm
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Post Options Post Options   Quote tink Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 1:56pm
Originally posted by iGRF

So what’s now being suggested the Contender doesn’t need a wire and trapeze at all because you’re an Engineer and I’m in marketing?


You could fit wings on a contender and the crew could create the same righting moment as a trapezing crew, the key thing is where the crew c of g is. As a engineer this stuff is my bread and butter so my understanding of this stuff is rather relevant.
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 2:27pm
Originally posted by tink

Originally posted by iGRF

So what’s now being suggested the Contender doesn’t need a wire and trapeze at all because you’re an Engineer and I’m in marketing?


You could fit wings on a contender and the crew could create the same righting moment as a trapezing crew, the key thing is where the crew c of g is. As a engineer this stuff is my bread and butter so my understanding of this stuff is rather relevant.


Well I would beg to differ, then what do I know, I've only spent thirty odd years marketing harnesses and harness hooks in wind and more recently kitesurfing where the idiosyncrasies are very different. So you'll excuse me for choosing to find out for myself, when I can find a suitable harness with the option to vary hook height.

As for fitting racks on a contender, or using your Toy example, they may very well apply sufficient righting force but they will be slower. If you are truly an expert engineer, then I shouldn't have to explain why, but if you wish, I'll try and find a better drawing programme to illustrate why.

Edited by iGRF - 03 Jan 22 at 2:29pm
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 2:28pm
Originally posted by tink

Originally posted by iGRF

So what’s now being suggested the Contender doesn’t need a wire and trapeze at all because you’re an Engineer and I’m in marketing?


You could fit wings on a contender and the crew could create the same righting moment as a trapezing crew, the key thing is where the crew c of g is. As a engineer this stuff is my bread and butter so my understanding of this stuff is rather relevant.

The B14 is a good example, huge racks and a 3.05m beam give the same righting moment as a trapeze would, note where the crew's feet are.





Edited by Sam.Spoons - 03 Jan 22 at 2:32pm
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Post Options Post Options   Quote Do Different Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 2:39pm
Give it up people, there's nothing to be gained here.    iGRF has an undoubted history of being a demon windsurfer and marketeer but time and time again he has demonstrated that he entirely missed out on secondary school physics lessons. I have respect for skills and wish him well with his Contender experience.

Edited by Do Different - 03 Jan 22 at 2:44pm
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jan 22 at 2:40pm
Originally posted by iGRF

As for fitting racks on a contender, or using your Toy example, they may very well apply sufficient righting force but they will be slower. If you are truly an expert engineer, then I shouldn't have to explain why, but if you wish, I'll try and find a better drawing programme to illustrate why.

Interested to hear your explanation?
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