Best process to maintain steel deck

[gauvins]

My boat is a 30 y/o steel cutter. The hull was assembled by a competent boatyard. It's been blasted with molten zinc and painted with the Awlgrip system.

The deck has started to show several rust spots in recent years. Most being cosmetic surface stains, but some, around portholes especially, are more serious.

I've tried random systems with more or less success. I'd now like to get to the bottom of this.

I can't justify the cost of a professional refit - i.e. remove everything, sandblast/prime/coat, reinstall everything. So it'll be hunt-and-fix.

Since I don't think that I can bring back nooks and crannies to white metal, I assume that a rust converter of some kind would be the first line of action. Then followed by a primer (one or two part?), then covered by a couple of coats of surface paint (ex. inter deck).

I'd be happy to read advices/comments. If there are good instructions online, please post links. Most of what I came across were suggesting white metal. Nice but can't do.

[Edit]

Might be useful to add that it appears that the primer separated from the zinc layer over time. I can scrape fairly large scales of material that will reveal steel and mostly corroded zinc layer - white powdered zinc residues and dark rusty steel surface.

Here and there, the surface is covered with bubbles that hold water, leading to corrosion

[coopec43]

gauvins

Sorry I can't help you as my yacht is a Robert Mauritius f/g. But there's a fair bit of advice on different forums.

www.cruisersforum.com › Cruisers & Sailing Forums › The Fleet › Monohull Sailboats
Steel Boat Maintenance - Cruisers & Sailing Forums

Aug 9, 2009 - 15 posts - ‎10 authors
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Is this any good?

Skunk Rust: Welcome

“Skunk Rust” is a rust de-oxidizing primer that not only stops rust on contact but will consume all ferric oxide while producing a toothy structure which will double ...

https://www.youtube.com/watch?v=D7NtZ2Ix6nU

Opinions of Skunk Rust and Pickle X
https://www.chevelles.com/forums/12-...-pickle-x.html

[conachair]

Well worth a download imho -
https://www.amazon.com/Metal-boat-ma...Scott+Fratcher

[MartinR]

The main ingredient of rust removers is phosphoric acid. It also removes rust stains. A treatment will not prevent rust, but will slow it down. Many layers of primer also slows the rust down.

To completely stop the rust, you need to sandblast. If it is only small spots, you can use a cheap spot blaster, typically used for cars. Before blasting, grind it down to bare metal.