Epoxy / Glass Over Aluminum ?

[capngeo]

I was out in an ideallic tropical anchorage last week, when the ugliest boat I ever saw pulled in. It's lines reminded me of the shuttle from star trek. It was a cold molded cat with amazing space and ventilation. She can make 10kts with only two 9.9hp o/b Yamahas @ 0.5 gph each!

The owner is building another, except this one will be epoxy/glass over 1/8" aluminum....WITH A MAST FOR SAILING TOO! I think I'm in love with the idea!

The real kicker was watching it pull up to the beach (while I was 100yds off) and plow right up at low tide, the owner WALKED off and tied a line to a mangrove root, then went exploring.

So, my esteemed and knowledgable Internet think-tank.... What say you about building with epoxy/glass over aluminum? I've never heard about it before! I am thinking about selling the mono, and building one of these for myself!

[noelex 77]

Its hard to know what the glass achieves.Skipp the glass and just go with aluminum. Stronger more abrasion resistant and no risk of crevice corrosion compared with an aluminium glass combination.

[CharlieCobra]

If the aluminum has been acid etched and alodine treated, applying C-Flex onto a base of 3M 5200, as you would a wooden boat hull, would work nicely. Forget about ever getting it off though....

[motion30]

sounds as though the alu was used a the form with the glass is the strength The epoxy can really grab it done property

[capngeo]

Originally Posted by motion30

sounds as though the alu was used a the form with the glass is the strength The epoxy can really grab it done property

EXACTLY! Not to mention the galvanic isolation aspect.

I,ve been scribbling on a napkin, and a 40'x18' LOA boat would fit my needs nicely, with a 20' deck house. 3' beam x 4' depth x 40' hulls would be ~12k #buoyancy per foot of displacement with a shallow v and a keel. Giving a six ton boat a 12" draft.... Not too shabby

[capngeo]

Now I need some small diesel outboards!

[minaret]

Terrible idea! The glass will delaminate from the aluminum eventually. Even the most careful etch and alodine will eventually fail, even with epoxy. I remember stripping all the fairing compound off of a deerfoot 63, re-etching, priming and fairing, then re-priming and painting, because the bond had failed and corrosion was setting in due to water trapped under the fairing. Believe that job cost about 100k. And Dashew's yard was very diligent on the prep of their aluminum hulls. I have yet to see anything stick to aluminum longer than 20 years...

[s/v Jedi]

Originally Posted by minaret

Terrible idea! The glass will delaminate from the aluminum eventually. Even the most careful etch and alodine will eventually fail, even with epoxy. I remember stripping all the fairing compound off of a deerfoot 63, re-etching, priming and fairing, then re-priming and painting, because the bond had failed and corrosion was setting in due to water trapped under the fairing. Believe that job cost about 100k. And Dashew's yard was very diligent on the prep of their aluminum hulls. I have yet to see anything stick to aluminum longer than 20 years...

Yes and the lawsuit that followed took years and most of Steve's hair.... but that was the only time he had a problem with aluminium shedding it's paint and there are thousands and thousands of painted aluminium boats that do not have the problem. I can make epoxy stick to aluminium in a way you never get it off again with no prep work at all. Just brush the epoxy on and immediately brush it into the aluminium with a stainless steel brush (mechanically removing the oxide underneath the fresh epoxy).

p.s. there is no Dashew yard. That boat was painted in Scandinavia/ Denmark or something IIRC.

ciao!
Nick.

[capngeo]

West System, seems to think it will work fine with G-Flex 650 resin