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broken daggerboard

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ModifiedC-Class View Drop Down
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Post Options Post Options   Quote ModifiedC-Class Quote  Post ReplyReply Direct Link To This Post Topic: broken daggerboard
    Posted: 19 May 06 at 4:30pm

snapped a dagger board on our old C-Class cat yesterday screaming along at 20knots and all of a sudden bang followed by a shudder thought what the hell was that looked up at the rig expecting the worst but couldn't see anything amiss ( we where struggling back across the solent in what we later found out was 28 to 30 knots of wind that was gusting to nearly 40 knots ) it was only when we got back to Calshot that we realised we now had a very short board.

Anyway the daggerboards are Grp moulded using chopped mat with wooden strengthening battens, I can take a pair of moulds from our surviving board easily enough but would like some advice on strengthening the design as the other board is cracked as well ( PS they are 6ft long)

I refuse to tip toe gently through life only to arrive safely at death
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Isis View Drop Down
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Post Options Post Options   Quote Isis Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 06 at 5:02pm
Initial impression is that the flaw lays with the fact there seems to be a bit too much chopped strand in your carbon layup...
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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 06 at 5:10pm
Make it out of foam with some carbon stringers. Or infact make it out of
foam with anything but chopped strand mat!

go here for a bit more info and some nice How To Do it Videos.....

http://www.sailingsource.com/cherub/chframe.php?menu=build

or you could PM me and I'll send you the mpeg if the website ones are to
small.
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Captain Aris View Drop Down
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Post Options Post Options   Quote Captain Aris Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jun 06 at 11:40pm

It looks like the wood is there not so much as added strength as for shaping the internal ribs which give the dagger board extra stiffness.

In view of your experience I would mould the new daggerboard with roving or glass cloth rather than chopped mat. At least some glass cloth on the outer surfaces. And I would make the walls a bit thicker than they are.

I think it is also a good idea if you can manage to get the internal ribs to meet exactly along the center line.

Beware of more sail than ballast.

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