Best type of bolts/screws to use with fibreglass...???

[canadian_cowboy]

Hey, I am now underway building the mold and almost ready to start laying fibreglass and I want ot look at getting the hardware and trim soon. I'm wondering which type of fasteners (bolts) and hardware is best to use with fibreglass. I'm thinking stainless steel bolts, hardware etc... but someone suggested that galvanized or regular untreated steel might be the best...
Any suggestions???
Thanks,
Rob

[Misogynist]

Are you talking about fasteners for the mold?... Or are you talking about fasteners for the boat... If they are for the finished boat.. only stainless or brass should be used... Galvanized will last about two days... bare steel even less.... I've seen steel grabber screws used to lag in a stereo amp. Even though the amp never got splashed... or saw water... the screws were rusted away in a matter of a few weeks. On the engine, many high strength steel bolts and fasteners are used... but if they aren't stainless.. then they are heavily painted. Even the cad plating or zinc plating on steel bolts doesn't last long in a salt water environment... Anything that is seen and attached to fiberglass should be stainless.

[canadian_cowboy]

Hey,
thanks for the advice, will be much appreciated when I still have half decent fittings after 2 days

[frastorno]

And what about alluminium screws? can they be used istead of stainless steel? I want to use them to fix the hull to the fiber glass top (basically the roof of the cabin and the top border all around the boat). That because the conection between these 2 parts is covered with an alluminum rail that support a rubber tape for protection while docking, and the screws i need to use will also keep the alluminium in that position. I'd like not to mix different materials. Are they too week?.. corrosion?

[alan white]

Aluminum comes in many flavors, and in the case of screws, I would use stainless for strength. Whatever aluminum screws are out there, I doubt they are made from aluminum that can stand the assault of salt water.
Even the right aluminum, if found, would likely not stand up to the torquing required to install them nearly as well as stainless or bronze. Brass is not suitable for anything structural. It may be used where a lot of fasteners are needed for uniformity, or for ornamentation such as hanging a mirror in the head, but brass is very weak tensily and given to corrosion if submerged.
Stainless is fine abive the waterline, and below bronze should be used if it's going to get wet. Stainless will corrode if deprived of oxygen in a wet environment. Stainless is a quarter the cost of bronze right now, I think, so whereas it would be nice to use bronze throughout, it just isn't cost effective while copper is so high.

Alan

[frastorno]

Thx for the info, it seemsthat stinless is the solution then. As those screws are attached to an alluminium component, won't that create galvanic corrosion?

[alan white]

To a small degree, yes. However, virtually all sailboats using aluminum mast, booms, cleats, and similar hardware have used stainless screws for attachment for over fifty years.
You would note that aluminum will corrode around stainless fasteners on masts of older boats, a whitish erosion surrounding the part attached.
There are ways to prevent or at least limit the contact between the two dissimilar metals, specifically coating threads prior to fastening. I am no longer dealing with that issue, as I build mostly wood and prefer bronze screws, cleats, and other hardware. As a result, I am not up on the latest products available to coat fasteners. I know they can only have improved in the last few years. I used to use a thread locking liquid, Locktite, but i'd google for the latest stuff, or someone here could help you.

Alan