advice please on aluminium hull in sea water

[thatmandan]

I've recently bought an ex-lifeboat (built 1954) with an aluminium hull. My hope is that she can be happily moored in sea water as a live aboard. Problem is that I've been getting lots of conflicting advice. Some people say that the salt in the sea water is a threat and that sheathing isn't an option because she's covered in rivets which are 'proud'. Other people seem to think that I could get away with the right primer + paint but that I will need to get a few anodes (to protect against electrolysis) that will need to be replaced on an annual basis. Still others have suggested painting inside with tar or similar. The only thing that people seem to agree on is that I will need to replace the rivets that have oxidised already. Any help with this would be much appreciated - I can't possibly get any more confused!

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[Peterduck]

Aluminium boats are common here in Australia. Most of the smaller fishing boats used by the abalone divers and such are welded aluminium. They are built from a "marine grade" alloy and are often not painted at all. Most light runabouts used by recreational anglers are welded aluminium and frequently unpainted. A lifeboat would have been built by a profesional company of builders who should be expected to use the correct grade of alloy. This seems to be a fundamental point in the construction of boats from this metal. The environment is also important. An aluminium boat stored among other boats in a marina could easily be ruined by electolysis within a year, but left on its own on a swing mooring may well be fine. I am deeply suspicious of cast aluminium in the marine environment, as I accidentally broke a casting many years ago, to find that it contained white powdery aluminium oxide throughout its thickness. Rolled [sheet] or extruded aluminium seems to be OK though.
Peter.

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[thatmandan]

Thank you for that Peter. It's great to know what I need to protect my boat against in the marina and supports some of the other good advice that I've (finally) been receiving from other savvy people. I'm also starting to think that, if I'd known about this site sooner, a couple of them grey hairs up top would still be of the black variety! Many thanks again, Dan.

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[John_Hampton]

Dan, see question put on Practical Boat Owner forum on 29/9/2003, there is a lot of advice there.

Regards

John

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[Coppershield]

Hi, is Your boat out of the water?
Do You have any pictures of the bottom? (problem areas, running gear)
what do you mean by sheathing? (sheating with what and what...for?)
Thank You.

Muzaffer


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