[Alberg30] Deck Coring

J Bergquist j at ship.saic.com
Thu Jun 20 07:30:59 PDT 2002


C.B.

I haven't done this job on a boat of my own, so take my advice with that in mind. I would caution against using option 1, because it is a stopgap solution at best. At worst it is just a waste of time and effort and will probably only make the recore job more difficult when you do eventually have to do it. If you plan to either keep or sell the boat, it would probably be best for your resale or for your use of the boat do do a good recore job. 

As regards the epoxy, I am a huge proponent of west system for personal use, even though it is more expensive than the MAS. I haven't used MAS very much so I don't know that one. However, I did once buy a bunch of 'Barrier' epoxy from Defender and had a lot of problems with proper cure. I had to use heat guns to get it to work. I have found that West system is the most forgiving epoxy in terms of mixing (the proportions still have to be accurate, but for some reason West seems to work even if they are a little off, like when the pumps get air bubbles, or I have even just dumped roughly right proportions into a cup and it still worked famously). I did have some friends that built a kayak with MAS because it was cheaper and they had some cure issues, I think. West has never failed to work flawlessly for me, so I think it is worth the extra cost. If you're a professional, using gallons of the stuff every day, it pays to find a cheaper brand and get to know its idiosyncracies. B!
ut if you're just doing a recore job, you want the epoxy to cure right the first time, and you don't want to monkey around with what turns out to be a big sticky mess if it doesn't cure right, so I advocate sticking with Gougeon. That's enough about epoxy.

Regarding core, you could use foam, or you could use end-grain balsa. I would check prices. End grain balsa is probably cheaper. If you bed the core right (especially if you vacuum bag it in to ensure proper adhesion of the core bedding to the core and laminate), it will be totally waterproof and then you just have to be careful when you install hardware not to leave any of the core exposed where water can get to it. 

Foam will probably be lighter, soak up less resin, and might be more rot resistant. But it will probably be more expensive and harder to work with (because even scored foam tends to be pretty stiff, where balsa is more flexible). However, the rot resistance of foam should not be over estimated and depends strongly on what brand and type you use. 

You could also consider using plywood, but I think the balsa would be a better choice. It is much lighter, same rot resistance (probably better in fact, since the end grain tends to keep water localized), and probably about the same price. 

I'm real interested to hear if anybody has some specific information about different flavors of foam core. 

J Bergquist
Calliope #287

 +---------------------------------------------------------------+
 |  Boatowners Mechanical And Electrical Manual by Nigel Calder  |
 | http://www.amazon.com/exec/obidos/ASIN/007009618X/alberg30-20 |
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