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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: 15 Jan 05 at 12:38am

Originally posted by Bruce Starbuck

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

Ah, I can see you've never sailed a Cherub

Just kidding, I was completely wrong. It isn't cavitation but aeration. I rather like the fact they have a nice short foil at the surface piercing point and still keep pleanty of surface area under the water to make sure they can steer at Mach 10 (approx.)

Fly Cherub!
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Barty View Drop Down
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Post Options Post Options   Quote Barty Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 05 at 9:22pm

The short chord limits the effects of ventilation.   When a wing or foil is working there is a low pressure and a high pressure side.  Now the low pressure like nothing better than to mix it up with the high pressure side.  Ventilation is when you have a foil operating at a medium (air, wter etc) interface, i.e. in the water right by the surface.  The low pressure flows up the foil to meet the air and equalise itself. When this happens you lose lift and you create drag.  Viewed from the rear (!), the rudder will have unequal water levels on each side.  This is the ventilation. 

The shorter the chord the less lift and hence less ventilation there can be and therefore the less drag.  If you don't put fences at the top of your rudder then you will just have to accept ventilation.  Rudders would work much better with longer chords lower down but the engineering (too much stress at the stock) stops this.

Btw the pressure differentials created across foils can mean that water boils and hence cavitates.



Edited by Barty
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sailor.jon View Drop Down
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Post Options Post Options   Quote sailor.jon Quote  Post ReplyReply Direct Link To This Post Posted: 16 Jan 05 at 10:14pm

right its coming up to that dreaded time again, monday morning, so does anyone have a photo for the week about to start?
something to get me thru monday at least, i love looking at the pictures people post, it gets me looking 4ward to the weekend. i have a choice sit n do my ict projects thats like a massive part of the final grade or come on yachts n yaching, i think u can guess which wins

  

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Tornado_ALIVE View Drop Down
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Post Options Post Options   Quote Tornado_ALIVE Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 6:44am
Originally posted by sailor.jon

right its coming up to that dreaded time again, monday morning, so does anyone have a photo for the week about to start?
something to get me thru monday at least, i love looking at the pictures people post, it gets me looking 4ward to the weekend. i have a choice sit n do my ict projects thats like a massive part of the final grade or come on yachts n yaching, i think u can guess which wins

  

 

Here ya go Mate...

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Chris 249 View Drop Down
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Post Options Post Options   Quote Chris 249 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 8:26am
Hmmmm, Mistral sailor in the background sheeting in and loving it, some guys on a Tornado with the forward hand standing there brave and tall and the skipper skulking down to leeward, too scared to get on the wire. If you look closely, you can see his white knuckles and terrified brow from here, and yet he sails that old people's home known as a Tornado rather than a fast lively cat like a Taipan 4.9.......what's wid dat guy???? As my forward hand/skipper says, a Tornado worlds is the sort of regatta you do the season after you start sailing, before you get onto macho boats like Lasers and windsurfers....

I bet he didn't even sail this Sunday......WE would have sailed this Sunday, of course, if only we hadn't agreed to let some Vicwegians use the boat. We woz raring to go.


Edited by Chris 249
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ed490 View Drop Down
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Post Options Post Options   Quote ed490 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 11:43am

How about this?!

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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: 17 Jan 05 at 11:48am
That water loks like bileous vomit
regards
Dr. Clifford

take two tablets twice daily
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sailor.jon View Drop Down
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Post Options Post Options   Quote sailor.jon Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 5:19pm
hey cheers guys that managed to get me thru the day,

both pics look great, the water on the second one looks like yeadon tarn. tho it cand't be cos the tarn is so shallow :'( not deep enough 4 me to put down the daggerboard on the laser 2
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Phil eltringham View Drop Down
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Post Options Post Options   Quote Phil eltringham Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 5:41pm
Is it a 'spot the helm' competition?
FLAT IS FAST!
Shifts Happen
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sailor.jon View Drop Down
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Post Options Post Options   Quote sailor.jon Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 05 at 8:01pm



u reckon this could be real??

i'm not to sure,
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