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fab100 View Drop Down
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    Posted: 04 Jan 22 at 6:13pm
Originally posted by iGRF

Which still gets back to the original question, what's best to achieve that high or low hook?


Mozzy’s et al have told you, pay attention - hook should be just above your CoG.

If you want more righting moment you need to trapeze low, perpendicular to the mast with the boat absolutely flat as that moves your CoG out marginally further. And be out in your tippy-toes, and in platform boots in your case. Which all works as long as you are not crashing into waves, obvs.

As usual, the moral is that if you’d learn to apply accepted best practice, you’d gain far more on the water than by trying to invent new tricks that aren’t there.

Interesting thread tho; it’s wakened the place up.
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 5:59pm
Griff, what do you make of the 'dead downwind speed' thing? Thought you would be all over that.
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iGRF View Drop Down
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Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 4:54pm
Which still gets back to the original question, what's best to achieve that high or low hook?
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Posts: 3400 		Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 2:46pm
Originally posted by iGRF

I know I've read somewhere the wider area the weight is displaced over, the earlier to plane, it was the physics behind formula boards, it's why wide goes earlier than narrow, and I'm sure the fact that c of g of that out fit moves from the centre line further to weather and the bigger the weight component of the crew of the whole package the earlier it all goes.
Now I'm not disputing all your schoolboy physics bollox, but I swear to God there's more going on with this weight transference, now wether it's the wire angle, the helm angle, but nothing has changed with all your calculations except at some point everything knotches up, and we breakout.

I'm guessing it's 'cos it's never a steady state, windsurfing we'd pump a couple of times in a gust to get over the hump, the act of extending to windward to counterbalance a slight increase in wind strength will have a similar effect if you are on the point of planing anyway. Once you are planing there is less boat in the water thus less drag so you don't need as much power to keep planing as you did to get planing.

I agree WRT the wide/FW idea, I think boats are not so different to windsurfers when it comes to the effects of rocker and planing areas and the basic concepts, that wide flat planing areas get going sooner than narrow/curvy ones is easy to see as is the trade off that wide flat boats are slower in displacement mode.
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ChrisI View Drop Down
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Posts: 143 		Post Options Post Options   Quote ChrisI Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 12:09pm
PS Very interesting data analysis on the RS800 from Mozzy... many thanks.
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Posts: 1151 		Post Options Post Options   Quote 2547 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 12:00pm
Well I have missed a lot since starting this topic ... I wasn't really expecting to see some people trying to rewrite the laws of physics but I should have expected that.

Anyway ... seems the answer to my original question is that weight equalisation in dinghy sailing is a concept that is almost forgotten bar a few classes in the UK.
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iGRF View Drop Down
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Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 11:56am
Originally posted by ChrisI

Love the discussion and Happy New Year to all.
Nice picture GRF and glad to see you've been out over Christmas/New Year.
Here's a suggestion on your original question (from another engineer ) if you have a spare moment in a coffee break.
Make up a model but make it with one mast and a trapeze (with weight etc) EACH side so it is exactly balanced.
Then without changing the position of the weights change the attachment point on one of them and see if the thing unbalances.


Yes, exactly what I was planning to do, have even got a set of warehouse scales to set it all up on.
Just need to set it up with a model helm that won't shut up moaning all the time.
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iGRF View Drop Down
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Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 11:53am
Originally posted by 423zero

How was your back? You must have good core strength.


Yes, luckily I have, formed years ago water ski race training then windsurfing and mountain biking help. I've also been lucky with my back and knees given the punishment I've handed them all these years and learning this dinghy sailing sh*t is probably the worse, but each year a little better than last, which at my age is something to treasure.
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ChrisI View Drop Down
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Posts: 143 		Post Options Post Options   Quote ChrisI Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 11:52am
Love the discussion and Happy New Year to all.
Nice picture GRF and glad to see you've been out over Christmas/New Year.
Here's a suggestion on your original question (from another engineer ) if you have a spare moment in a coffee break.
Make up a model but make it with one mast and a trapeze (with weight etc) EACH side so it is exactly balanced.
Then without changing the position of the weights change the attachment point on one of them and see if the thing unbalances.
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iGRF View Drop Down
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Posts: 6499 		Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jan 22 at 11:43am
I know I've read somewhere the wider area the weight is displaced over, the earlier to plane, it was the physics behind formula boards, it's why wide goes earlier than narrow, and I'm sure the fact that c of g of that out fit moves from the centre line further to weather and the bigger the weight component of the crew of the whole package the earlier it all goes.
Now I'm not disputing all your schoolboy physics bollox, but I swear to God there's more going on with this weight transference, now wether it's the wire angle, the helm angle, but nothing has changed with all your calculations except at some point everything knotches up, and we breakout.

Edited by iGRF - 04 Jan 22 at 11:45am
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