Originally Posted by taskswap
Specifically, it hardly expands/contracts at all. It is an extremely rigid material. When doing things like skins over metal you just need to elongate the holes a tiny bit. Metals expand/contract "a lot" - but only relative to not moving at all. They don't grow inches. You only need to make a round hole 1/16" or so longer to allow for it, depending on what you're doing. There are some side benefits, though, like no galvanic corrosion, it's waterproof, can never rust, etc.
This only applies to exterior skins - which may not be the best use, anyway. It's almost never a problem with smaller things. Fiberglass does take some work, and the work is directly proportional to the piece size. It's REALLY good for doing things like trim work, making ducts, supports, mounting brackets, etc. It's SUPER good when making odd shapes, things you'd need a bending brake and some experience to make out of metal. You guys that are good at welding probably wouldn't get as much mileage out of this, but it's amazing what you can make.
I'll post some videos of this soon when we finally get to work on ours.
Three years ago I bought a project boat and completely rebuilt it. I gutted it all out, floor, stringers, everything right to outer shell. I used to build a copy/replica boats when I was kid, but it was all on a small scale. From my experience rebuilding my boat I can say it wasn't so straight forward.
There are many little things you need to know how and why and why not.... when it comes to fibreglass.
Most people don't even know the difference between epoxy and polyester. Using fibreglass is easy when you know what you are doing and it is easy to screw everything up.
Most of us used or tried to use Bondo car putty but not many know that Bondo is a polyester resin with filler and small tube that comes with it is a MEK catalyst. Here is a very good article about it:
What Exactly is Body Filler?
Most people have no idea that you can use epoxy over polyester but can't do it vice versa....
Most people have no idea that epoxy "welds" to wood but polyester doesn't bond too good to wood, hence many boats have delaminations here and there...
Most people don't know that strong epoxy is very sensitive to UV but weaker polyester holds UV much better.
The whole polyester/epoxy industry is very complicated. People mix up terminology, call things wrong way, creating even more confusion....