Rust problem

[pzmaria]

Hello members, I have quite extensive problem with rust showing and discolouring everything around. It's and older (1986) Cat30. After cleaning rusty spots just after 1-2 days at sea they come back and make everything look ugly. Any ideas what is causing this and is there anything I can do to stop this? Removing this stains is so hard. What would you suggest to use for effective removing this? Thank you for any pointers and advice.

[Vasco]

To stop the stainless rusting like that you really have to passivate it. I've found Spotless Stainless to be a very good product for cleaning and passivating.

https://www.mmsonline.com/articles/h...ss-steel-parts

[Vasco]

As Spotless Stainless is not cheap I would first give it a clean with Barkeepers Friend (cheap, sold in Walmart and Publix, essentially oxalic acid though some say it also has nitric acid in it) and then use Spotless Stainless.

[Cheechako]

My bet is the stainless steel. Especially the enclosed part where the pulpit and lifeline stancions mate to the deck. Wet enclosed areas create oxygen depletion and SS corrodes well in that environment. you need to:
-remove all those, (a big job) clean them up removing all traces of rust and maybe have them re-passivated properly by a railmaker shop.
-Replace all the bolts with new.
- I bet you will find those bases are totally rust covered on the bottom. It's probably time to rebed all those fittings anyway, they may already be leaking into the deck core, but you may be lucky with the stancions and pulpits as they may not have carried the coring out that far on the deck.

[Suijin]

Originally Posted by Cheechako

My bet is the stainless steel. Especially the enclosed part where the pulpit and lifeline stancions mate to the deck. Wet enclosed areas create oxygen depletion and SS corrodes well in that environment. you need to:
-remove all those, (a big job) clean them up removing all traces of rust and maybe have them re-passivated properly by a railmaker shop.
-Replace all the bolts with new.
- I bet you will find those bases are totally rust covered on the bottom. It's probably time to rebed all those fittings anyway, they may already be leaking into the deck core, but you may be lucky with the stancions and pulpits as they may not have carried the coring out that far on the deck.

I think you're spot on. That's just too much rust to be coming from the surface after it's polished after just a few days. It must be internal bleeding out under the bases.

And if that's happening, there's a 95% chance it's leaking down through the bolt holes.

No doubt, it is a big job (having just done it), particularly if access to the underside is poor, but doing it will not only stop the rust staining but will protect the core.

I've used Spotless Stainless and was not impressed. Didn't do squat on my rust staining at all, most vexing. Yard where I'm at had some Wonder Gel...brush it on and 10 minutes later the rust is gone. It's pricey but a little goes a LONG way.

For deck rust stains it's hard to beat Mary Kate's ON/OFF.

[Sea Q]

I agree with Cheecako
it is best is to remove clean and reseat

After that i would spray paint with clear coat automotive paint out of can
I have done this method with a tender roll bar and the side air vent louvers on the big boat ----No one sign of rust in the last 5 years and it stays shiny

[zeehag]

rebed after inspection. replace and/or fabricate as needed

[barnakiel]

Sometimes it is the bolts.

At other times it is the stanchions material or manufacturing errors (e.g. the bases ground with a dirty disk).

Remove and clean. Passivize the stanchions an use 316 bolts, washers, nuts.

b.

[Bleemus]

Those bolts dont look like 316 stainless. Replace them all and then treat affected areas with oxalic acid.