Anodes on Aluminium boats

[andyball]

Has anyone got any advice regarding fitting anodes to an aluminium boat? it's painted & antifouled, and has a drying pontoon berth, The boat is 21'6" ,outboard motor (raised when berthed.

How many anodes? best place to fit......any other advice/horror stories?

Thanks in advance

 

[extravert]

I used to have an Extravert 22, all welded marine aluminum. I had no problem with corrosion at all. The boat was 20 years old, and the surveyor said that the hull was as good as the day it was made.

I took these precautions

2 hanging zinc anodes attached electrically to the hull. The anodes are on wires. The zinc dangles in the water and the wire attaches to the hull above the water line. They are lifted and stowed when using the boat. The anodes need a scrape every few months to get the brown/white crud off, and replacing evey few years. They can be got mail order from chandlers.

Keep copper and mercury out of the bilges. No thermometers on board, take care with coins, check the bilges occasionally, and take care not to drop any bits if doing wiring.

Keep dis-similar metals apart if possible. For me this meant electrically isolating the keel (steel) from the hull, but this was already done by the builder.

With a little care, am aluminum hull is the longest lasting and least maintenance of all boat building materials, and is also very tough. And that's why insurance companies like ally boats.

 

[Guest]

Somebody I know with a Aluminium boat has fitted it out with magnesium anodes. It's a man with huge sailing/boating experience and I believe he knows what he's doing...
Be careful indeed with copper!