How to tell what material my hull is made of ?

[jim smith]

I have a old RPModeltech sub hull and it is very thin. I would like to reinforce it but am not sure if it's fiberglass or resign. How do I tell the difference? You can see by the close up picture that there are cracks and small holes in the hull.

[jim smith]

Here's the close up

[bob the builder]

I'm pretty sure that Rick used epoxy and cloth in his kits, but I've only seen his Foxtrot and Kilo kits up close.

His kits were very light layups. I have the two boats that I mentioned above and while they look amazing, I'm going to need to reinforce the parting lines to maintain alignment. Rick used a series of screws all down the side of the boat to get it to line up properly. It's almost as bad as cracking into an Engel dry-hull boat...

I'd say that if you rough up the surfaces you're trying to reinforce, using epoxy and cloth will be the most generically safe solution for you, not to mention the easiest to do (and the least smelly), if not the cheapest.

Bob

[lhdockyard1]

Interesting, from your close up picture I don't see the standard organized pattern that a cloth layup should provide. The randomness of the fibers sure looks like a mat rather than a cloth but from your overall shot, with the amount of light shining through the hull it must be a very thin layup if it is mat. My suspicion is that it is a mat layup and possibly in polyester as mat does not work well with epoxy. In any case the solution Bob provided is the best way to go.

Don

[jim smith]

Thanks for the help guys. I would like to reinforce the whole hull as it is very thin. Would you suggest building it up with thin layers or go with a thicker cloth right from the start? I know from the fiberglass hull I have and the plastic I use for vacuum forming hulls that the thickness is about .080-.090" thick. Should I try to achieve this thickness? Also I use Z Epoxy is that recommended or is there something else I should use?

Jim

[thor]

I agree with Don. It appears to be polyester. Mat cannot be used with epoxy. The fibers are treated chemically to release themselves from the mat after a reaction with the polyester resin. This allows them to form to very complex curves.

Your best bet is to use epoxy such as West Systems. Start your work with a 4 oz layer of BID cloth. You'll need 2 layers of 4 oz BID and 2 of 6 oz to achieve your desired laminate thickness.

[598602G]

Don, Matt I have used 2.5oz glass mat using epoxy on rc airplanes structures and that stuff stiffens up structures for sure. I have some .75oz glass mat that I am going to use in future hulls. The rpm Palumbo boat hull pictured above is epoxy as epoxy turns that amber color when it gets old.

[thor]

Glass mat should never be used with epoxy. It is designed specifically for use with polyester only. The binding chemical that reacts with the catalyzed polyester resin to release the fibers for movement prevents a complete mechanical bond between the epoxy resin and the glass mat.

Polyester can be the exact amber in color shown immediately upon curing depending on the solids content of the resin. Regardless, it is a guess only looking at the photos. Moving forward with epoxy is the best choice. Just be certain to rough the old glass up very well with 80 grit before laying up the new glass.

[jim smith]

Thanks for all the input. What is the cloth I should use with the epoxy and where do I get it?

Jim

[thor]

https://www.fiberglast.com

Look under fiberglass cloth under the products menu. You want 4 oz and 6 oz bidirectional cloth.

[jim smith]

Thanks.

Jim