Advice on fiberglassing deck of Shearwater Sport

Hi folks - I'm about ready to fiberglass the deck on the boat and hoping to avoid some problems I had with the hull.  When I did the hull I had a good many air bubbles pop up under the cloth, apparently from the holes where I'd removed the wire stitches.  These were quite a PITA to fix.  Hoping to avoid that problem with the deck.  Wondering about painting epoxy over all the holes, or just rolling a thin coat over the whole deck before laying down the cloth.  Thoughts?

Also, I have a wood veneer compass applique to put on.  Should the epoxy be thickened a bit with cellulose?  Should the epoxy be put on the deck or the bottom of the applique?

And finally, the cloth tape that I used to attach the deck to the hull is quite rough.  While I have the boat right-side up, thought I'd do something about that, at least in the cockpit area.  Should I fill the weave with more epoxy before sanding smooth, or just sand and brush on a finish coat of epoxy.

It's a big help for a newbie having you guys to ask about stuff like this.  Thanks.


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RE: Advice on fiberglassing deck of Shearwater Sport

   As far as air bubbles appearing under the cloth, some people will epoxy the deck first and then apply the cloth when dry to the touch but I prefer putting cloth on a bare deck. While proper temperature is essential, falling temperature is better than rising. If the the air temperature is rising after applying the epoxy, air traped in the wood can expand and rise up under the cloth, causing bubbles.



RE: Advice on fiberglassing deck of Shearwater Sport

   I'll leave (almost) all the fiberglassing guidance to others, but really some of the best advice is to watch the videos on this website.

The one thing I would recommend against, unless your make sure "dry to the touch" really means that there is no chance that the cloth will even sighty tack itself to the green epoxy.  You reay need to be able to smooth the cloth with your hands prior to putting on the wet epoxy.  Working out a the wrinkles with your hands and getly stretching it on the biases wil help ensure it lays flat.  Anyplace that the glass doesn't want to lay agains the hull when dry typically just becomes worse when "lubed" with epoxy.  If you do have a spot that won't lay down at a bend or a corner after you've wet it out, coming back when the epoy is tacky will sometimes get it to stick down.  A gently push with a brush seems even better than trying to rub it down with a spready.

Now on to the reason I took the time to post.  ABSOLUTELY DO NOT GET CELLULOSE-MIXED EPOXY NEAR YOUR VENEER.

RE: Advice on fiberglassing deck of Shearwater Sport

   Ooops.  Hit enter when I was getting ready to explain why no cellulose - sure, even if you think you're only gluing the veneer down, but will subsequently cover it with clear epoxly, you'll most likely get some squeeze-out, etc.. Anywhere you get the milky-colored epoxy, and your almost sure to get some on the surface of the veneer, and you only get a few thousandths of an inch to sand it off if you do, and if you don't you'll get amilky-colored area on the veneer. The fact that the unthickened epoxy might absorb more deeply into the wood isn't an issue - you're not looking to do much except hold the veneer down and maybe fair in the edge a bit when gluing it on.  So use only clear epoxy - nothing mixed in.  Once you cover it with glass it certainly isn't going anywhere.  Superglue is also a good choice for tacking down the veneer, so long as you are confident you can position it before the clue sets up.

RE: Advice on fiberglassing deck of Shearwater Sport

Hi Florida Jim, 

Bubbles, as pointed out above, are probably more due to glassing during rising temperatures than anything else.  for this boat, i would just make sure that you plan your work to ensure the temperature will be going usually around night fall....but check the hourly temperature forecast just to be sure.  the term is called 'outgassing'.  the wood has air in it,  when the temperature is going up the wood 'exhales' as the gas in it expands with the rising heat....making bubbles if a layer of wet epoxy is put over it.  you want the wood 'inhaling' when you are glassing it for the first time.

there is a method called skim coating, that is about rolling on a very thin layer of epoxy to plug the pores of the wood prior to glassing.   this prevents outgassing becuase the wood pores are now plugged.   but i think on this build, its a bit of overkill.  just pay attention to the temperature.

wood veneer, just straight epoxy....per bubbleheads point. i would put the epoxy on the veneer first then put it where its supposed to be.  you can use some scotch tapen to ensure the edges are held down.  epoxy won't stick to scotch tape.....and its not so strong that it will pull up the grain.  but the tape will not stick to wood wet with you need to ensure you are not sloppy. 

on your last question, knock down the rough edge with 80 grit sandpaper (make sure to protect your fingers from potential loose glass)...then brush a final coat of epoxy.

anyway, that's my 2 cents.



RE: Advice on fiberglassing deck of Shearwater Sport

   Thanks to all for the advice.  I'll let  you know how it goes.

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