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Old 01-03-2013, 12:02 AM
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CC2MC CC2MC is offline
MC Devotee
Join Date: Aug 2012
Boat: 2005 x-10
Location: Alabama
Posts: 1,405
Originally Posted by Cloaked View Post
So I ask... is fiberglass itself or a similar make of fiberglass/epoxy resin (for example a floor stringer that is supposedly all fiberglass makeup) conducive to tensile strength in the manner of, let's say, inserting a 3/8" x 16 x 2" lag screw into the material, holding something such as an engine mount, in place for setting the engine? The stipulation to this question is that there is no wood or other composite in-lay of material involved. Strictly a fiberglass stringer, per se.....

I ask this on the same theory of a concrete masonry unit... the CMU is great in compression but is very weak in tension.

Will fiberglass take good hold with a lag screw in a tension load?

With fiberglass, it really depends on the particular strand type and thickness used. Temperature and the type of resin used also plays a big factor. Generally speaking the tensile strength for fg is okay, but it is always a good thing if you can, to put a backing plate behind it and thru bolt it. I would not try to bolt the engine mount to a fiberglass stringer as the stringers are usually around 1/4" thick and filled with foam. I am not sure of the exact laminate schedule of a MC, but the size lag bolt you are talking about using is a pretty good size one and the tensile strength would not be great enough to support the load from the engine, unless it was built into the stringer from the factory. We would always thru bolt anything when we could bc it holds much better over time due to the amount of stress a fiberglass part is put thrugh. Why do you ask out of curiosity?

Sorry for the thread jack. Btw Blake, did u see the newest listing for a 96 205 in the boats for sale section?

Last edited by CC2MC; 01-03-2013 at 12:07 AM.
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