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Old 12-08-2008, 09:13 AM
LimeyInBr LimeyInBr is offline
 
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Fiberglass mast repair?

I just took over an unfinished 28í plyglass sailboat project. Problem is that everything here in Brazil is really expensve and the more I can do myself the better. I already got a bunch of good tips reading through back posts of this great forum. Thanks guys!

Present problem is this:
The mast is 34í and I have an unused 24í aluminum mast (section 7Ēx5Ē, thickness 3mm) complete with boom and spreaders, which I really want to use. Trouble is I canít find the same section to join so Iím thinking of constructing the missing top 10í in fiberglass.

I thought about making a permanent internal mould, either with foam, or plastic drain pipes, laying up epoxy/glass on the outside of this (spiral wound and longitudinal), and then gluing the new section to the old with epoxy.

I've atached a photo of the existing mast and a sketch of what I imagine the join should look like. Main problems I foresee are calculating the thickness of the new section and length of the internal sleeve, and matching the internal slider tube so the plugs donít snag - maybe Iíll just ignore it and fit a new external track to the whole mast after.

Iíve already found plenty of info about constructing freestanding and carbon fibre masts on the web but nothing on plain old glassfibre or joining mast sections.

Anybody have any experience with this or know of any sites with info?

Thanks in advance for any help.
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Fiberglass mast repair?-mastjoint.gif  Fiberglass mast repair?-mast.jpg  
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  #2  
Old 12-09-2008, 05:22 PM
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Eric Sponberg Eric Sponberg is offline
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A fiberglass mast section as an extension of an aluminum mast section is not going to work very well. Fiberglass is as bendy as spaghetti when compared to aluminum, and you'll have a really hard time keeping the fiberglass part of the mast straight.

In my opinion, you would almost be better off with making the upper section out of wood-epoxy. It could fit internally to the aluminum section and shaped so that the exterior surfaces are flush. You can start with a generous wall thickness, minimum 20% of the diameters all around, and plane it down to shape in pretty quick order, so you would not need any tooling of any sort.

I hope that helps.

Eric
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Old 12-09-2008, 05:43 PM
LimeyInBr LimeyInBr is offline
 
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Thanks, Eric.
I've seen a few smaller sailboat projects with instructions on how to make a wood-epoxy mast. Basically epoxying strips of wood together to get the basic profile and then hand finishing. Would a final layer of glass help hold it all together or is that unecessary?
Dan
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Old 12-10-2008, 09:56 AM
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Eric Sponberg Eric Sponberg is offline
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A final layer of fiberglass cloth all around would be fine, yes, mostly to seal the finish layer of resin and to toughen the surface against minor impacts from the sails.

Eric
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