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Blobby View Drop Down
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Post Options Post Options   Quote Blobby Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 8:52am
The big splash on the right must be where the helm / crew landed - 7m away from the back end of the boat...now that is fast...
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Doctor Clifford View Drop Down
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Post Options Post Options   Quote Doctor Clifford Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 9:30am
Originally posted by Adam84

Wow, wot a pic wish id of been
on that boat!!!


thought you ewnt to university??!!
'id of been'?

(only joking, beofre you fire one back!)
regards
Dr. Clifford

take two tablets twice daily
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sailor girl View Drop Down
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Post Options Post Options   Quote sailor girl Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 10:47am
what's ewnt mean!!!     'went'????
and beofre    is that by any chance an anogram of before?!
Sailor Girl, Queen Of The Forum!
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Lucy Lee View Drop Down
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Post Options Post Options   Quote Lucy Lee Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 7:55pm

er, wow.

Check out their very very groovy rudder, which has some pretty amazing features like the short chord at the point where it pierces the surface to reduce ccavitation at high speed.

I recon thats the most amazing foil I've seen since the hydrofoiling moths. I know what I'll be making for my next cherub rudder.

Fly Cherub!
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Brian View Drop Down
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Post Options Post Options   Quote Brian Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 10:14pm

ummm yeah... i understand that

im sorry lucy i havnt really a clue wat u just said, im not very knowledgeable on anything to do with sailing as a matter of fact. i can see that the rudder is a funky shape alright but i dont really get what it would do, much obliged if u could explain? (i know what cavitation is,i think, but not how the rope would stop it)

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Jamie View Drop Down
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Post Options Post Options   Quote Jamie Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 10:42pm

I'm fairly sure that "short chord" is a reference to the width of the rudder at that point. - you will see the concave curve on the top of the rudder making it a shorter shord at that point. Nothing to do with rope.

Of course I may just have made a fool of myself there. 

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Bruce Starbuck View Drop Down
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Post Options Post Options   Quote Bruce Starbuck Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 10:51pm

Chord is the straight line distance between the leading and trailing edges of a foil (or sail).  Cord is another name for rope!

 

 

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maxim View Drop Down
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Post Options Post Options   Quote maxim Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 10:55pm
And could you possibly explain what cavitation is...
(I'm not a marine engineer)

Max
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Bruce Starbuck View Drop Down
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Post Options Post Options   Quote Bruce Starbuck Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 11:19pm

Cavitation is the rapid formation and collapse of vapour pockets in a flowing liquid in regions of very low pressure. This most often happens when water boils at normal temperatures due to very low pressure on propeller blades. 

This doesn't happen on dinghy foils.

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Bruce Starbuck View Drop Down
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Post Options Post Options   Quote Bruce Starbuck Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 05 at 11:37pm

I think when a rudder stalls, it's due to the water flow detatching and air being sucked down the low pressure side from the surface, and is called aeration, or something like that.

A dinghy's never going fast enough to boil the water, so cavitation is a commonly used misnomer in this case.

Quite a few classes have rudders with a narrow chord where they pierce the surface. The 470s have been doing it for years. Not sure it makes a huge difference, and it's quite a test of foil building to go making it narrower right at the point where it needs the most strength!

 

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