Aluminum fuel tank + salt water spray

[Paulus]

Question for this leaned group: My fuel tank is mounted under the cockpit and directly above the shaft seal. As such, it sees occasional spray from the shaft gland - especially when it becomes time to tighten it up a bit...



The tank was replaced from black iron to aluminum when the engine was replaced in or around 1992 - it seems to have been coated with a clear material, like varnish, which is now coming off in the area where it gets hit by the occasional spray... I see no deterioration of the aluminum - it looks like fresh metal, there is no build-up of corrosion or anything else I can see that would indicate galvanic or corrosive action.

Should I re-apply a coating?

[Tim]

The first thing I'd do is replace that old cracked hose seen in the foreground... ;<)

Sometimes aluminum tanks are coated with epoxy at the time of construction, but this isn't a requirement, nor is it necessarily even the norm. However, I know of at least a couple tank builders who apply epoxy as a matter of course.

The problem with attempting to recoat it now will be how effectively (or if) you can achieve appropriate surface prep. Aluminum, more than just about any other material, requires meticulous and specific surface preparation steps to ensure proper adhesion of any coating. Given the tank's installation and what is surely challenging access to all areas, I can't imagine anyone could properly prepare the surfaces without removing the tank.

(Clearly, this was even a concern at the time the original coating was applied, leading to the coating failure you're seeing now and reinforcing my point.)

The good news is that bare aluminum tankage is fine (and common) as long as it's properly installed to avoid stagnating moisture, etc., but you should at least rig up a little spray shield above your stuffing box to prevent that salt spray, which over time will not do the tank (or anything else) any favors.

[Paulus]

Thanks, and, agreed - a spray shield is definately needed...

About that hose ;<) - it bothers me a little bit too, but I believe it's a piece of exhaust hose - reinforced and multi-ply - so it should not fail catastrophically (is that a word?) without showing considerable seepage for a while... right now the boat has so many other areas that need attention... and you know about the squeeky wheel...

Right now the biggest ticket is getting rid of smells -

Cleaned the bilge from about 2" of diesel soaked grime - including chunks of wood, tools, rags, and sawdust...

Need to de-grease the engine now that I have replaced or fixed anthing that leaked (why is everything pink on a diesel? Pink diesel, pink anti-freeze, pink transmission fluid and now pink raw water winterizing liquid.. sheesh)

Then I need to clean and tighten all the head and holding tank lines and valves - the boat stinks and the Admiral refuses to spend any real time down below...

But (sigh) you're right... that hose needs to be replaced...

Thanks for the comeback

[earlylight]

If the head hoses are old, chances are that the odor is permeating them. Check by taking a damp rag and wiping the outside of the hose. Sniff the rag and if the rag smells, the hoses need to be replaced.