Repairing Firefly Centreboard Casing

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highburyal
Posts: 43
Joined: Tue Nov 20, 2007 12:12 pm
Location: Forest of Dean

Repairing Firefly Centreboard Casing

Post by highburyal » Thu Jan 03, 2008 7:52 pm

Hi all,

Can anyone give me some advice?

The plywood(?) lining of the centreboard case on my firefly is rotten and I want to replace it. Does this involve dismantling the entire assembly or is there an easier way to do it? How is the board casing attached to the hog?

Also, hope to be going to Robbins soon for some veneer. What is the best glue to use when repairing fairey hot moulded hulls?

Thanks in advance,

Al

Rupert
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Post by Rupert » Thu Jan 03, 2008 9:11 pm

If rotten there, it will be rotten in other places too...
The ply of the case is rebated into the hog, making it rather difficult to replace. I've not replaced one myself (having found that it was the wood around the case that was rotten on a couple of occasions, which was cured by taking the keel off and redoing the veneers instead), so I will leave that to others.
Veneering can be done with epoxy (the obvious choice) or cascophen (the nearest to what they were built with). Cascophen is plenty strong enough, and has the advantage of less wastage, but it really is very messy. Epoxy fills any gaps better. Robbins do (or did) both.
Rupert

highburyal
Posts: 43
Joined: Tue Nov 20, 2007 12:12 pm
Location: Forest of Dean

Post by highburyal » Mon Jan 07, 2008 6:36 pm

Has no one got any experience of rebuilding a centreboard case they could share? Thanks, Al

Rupert
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Post by Rupert » Mon Jan 07, 2008 7:09 pm

I have in other classes, but they are slightly different. Best bet is to wait till the Firefly site has found a new forum host and ask on there. Or contact Ray Smith (who has done many Fireflies) direct - I expect his contact number is on the Firefly site somewhere
Rupert

Michael Brigg
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Location: Gosport, UK

Post by Michael Brigg » Mon Jan 07, 2008 9:16 pm

There was a vogue at on time for lining the case with formica.

The idea was that you would reduce the slop on the plate and improve upwind pointing ability. Not surprisingly this was quite quickly stamped on by the measurement committee as technically wedgeing the plate.

I always thought you might get away with painting the inside of the plate case with about 100 layers of epoxy but never had the time or desire to win enough to try it. OK, maybe 20 layers but you get the idea.

If you're going to rebuild the case I would reccomend plate stiffeners,at the front end extended out to the shroud plate. (Too much further aft I think would count as an extra thwart and is out of class.)

Have fun

Michael
Michael Brigg

Rupert
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Post by Rupert » Mon Jan 07, 2008 9:45 pm

The rules say it can be lined, by a non metallic substance no more than 1.5mm thick. But you would still have to have minimum width.
Rupert

Garry R
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Location: Chapel Allerton Somerset

Post by Garry R » Tue Jan 08, 2008 9:43 am

While we are on centreboard cases for Fireflies I am thinking ahead and do wonder how you manage to paint the inside of the case. I've not had a case so narrow as it's been Merlins up to now. Also wonder Rupert if I could take up your offer of a small amount of agba for replacing my few bits of rotten veneers. I reckon I would need a total of 3-4ft of the normal planking width but for sending it could be cut into foot lengths. Would it be possible for you to manage that? Thanks in advance.

Does anyone have a better way of getting paint off wood than nitromors. The top coats come away well but the last bits of blue paint - possibly an undercoat are well into the grain and are a pain to get out - nitromors seems hardly to touch it. I think it is where the original varnish has had a ding and the surface has broken and now the paint is in. I think I am going to give it a really good deepish sand all over otherwise she is going to turn out patchy anyhow.

chris
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Post by chris » Tue Jan 08, 2008 10:08 am

there's an eco friendly stripper - can't remember her name - but it's a white paste rather than a gel. It is much slower than nitromors but does not dry off like Nitro. Spead it on and cover with polythene leave it at least a day (or more it won't dry in some cases the longer the better). Use a stiff scrubbing or brass brush to clean out the grain. You might need to repeat the process. When clean scrub with jiff or some other cleaner and plenty of water evenly over the timber.

This stripper is much kinder to wood ( and your hands) as it is non-caustic. It seems to enhance the wood rather than leave it washed out. Because it works very slowly and doesn't dry you can work on the whole hull in one go. Given time it seems to go through layers well.

I used it on my albacore when I found nitromors wasn't doing anything. You just have to use it differently. I think the one I used was the cheapest Focus own brand. It really doesnt dry - I found I had forgotten a small area in one of the bouyancy tanks that I was replacing the top ply fortnight after I had applied the stripper the paint came off very cleanly.

Garry R
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Post by Garry R » Tue Jan 08, 2008 12:18 pm

Don't know if everyone has seen this video - click on the Firefly download to see the video of the Firefly hot moulding process

http://www.freewebs.com/faireyaviation/marine.htm

Rupert
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Post by Rupert » Tue Jan 08, 2008 3:08 pm

I've found a hot air blower works the best for stripping, and it dries everything out at the same time.
PM me your address, Garry, and I'll pop some agba in the post.
I waterproofed the inside of a West Wight scow case once by taping up the top when the boat was upside down and filling it with linseed oil! Amazing how many little gaps there were in the wood...there was still linseed oil on the floor when we moved 5 years later!
Rupert

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