multiple fiberglass layers question

Hey All,

 I'm a first time builder and my shearwater project is going great.  This forum has been an invaluable resource.  In a few more days i will be ready start glassing the boat and i have some questions.  I have read a number of posts mentioning how threads on the edges of the reinforcement layers on the hull are a nuisance.  Someone mentioned placing the extra layers underneath the large, main piece to avoid this problem.  So, are threads really that much of a problem?  Will placing the smaller fibglass sections under the larger one result in any loss of strength? Are the ridges created when doing this easy to smooth out since you cant "feather" the edges of the underlying glass? Thanks for your input!


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RE: multiple fiberglass layers question


There's a good thread on this subject from a few months ago. I can't remember all the details, but the consensus seems to be that doing the multiple layers per the instructions is the way to go. The messy threads look like crap during the initial glassing, but disappear through sanding and additional coats of epoxy. There are tricks for minimizing loose threads, but they're not worth worrying about in my opinion.



RE: multiple fiberglass layers question

I would just do it the way it is stated, the edges will feather out and disappear under the expoxy.....happy building .... Ocean

RE: multiple fiberglass layers question

Here's a handy little tool for cutting fiberglass cloth on the bias. Makes nice clean edges that tend to not fray. Well worth the purchase for creating custom shaped, bias cut pieces for the stem and transom areas.

Rotary Cutter

RE: multiple fiberglass layers question

Thanks for the info guys!  I'll stick with the manual's method.

RE: multiple fiberglass layers question

I was the one who asked the same question a few months ago, in an earlier thread. I found that cutting the 'glass with a pinking shear helps reduce threads. I was convinced by the other builder's comments to go according to the instructions.

However, on my next build, I may consider omitting the 3rd small pieces at the bow & stern. They make a total of four layers of fiberglass, including the tape you applied on the inside. I've seen builder's notes on other message boards, where they just did a full hull layer, and a bottom layer. Also, where the instructions called for 3 additional layers of fiberglass in the deck area behind the cockpit, I only used 2, and it came out perfectly strong. I think the otherwise-excellent instructions have just a teeny bit of "overkill-extra-measure" built  in, unless you plan on hard use, like pouring 8oz. of epoxy in the ends. I whittled blocks of cedar instead, and glued them in.

RE: multiple fiberglass layers question

I've found based on using my Shearwater that extra glass applied on the hull at the bow and stern (actually along the centerline of the entire boat - a keel strip) are epoxy/glass well spent.  These areas seem to get hardest hit while beaching (and transport if you happen to, for example, lose your grip and one end hits the pavement - not that it's ever happened). 

I didn't find the loose threads too much of a pain - cut a few of the worst ones during the epoxy process and the rest sanded out fine.   I think that a rotary cutter would work great - you can get a cutter and the mat to use it on at a fabric or quilting shop as well as online.  


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