Rust spots on deck

[bats]

First noticed this in Ireland about a month ago. Now encountered this in Devon. A light grey very fine dust has appeared on the deck and coachroof. This contains some iron or iron compound that reacts with salt water to produce pin-pricks of rust on these areas. The spots can easily be removed with Y10 but their appearance is annoying.

 

[Andrew_Trayfoot]

Have you drilled or cut something metallic in the vicinity?

 

[bats]

No ... and the spots cover most of the deck and superstructure, although less significant in density than the pic shows.

 

[Poignard]

Perhaps you have been berthed next to some selfish idiot using an angle-grinder?

 

[KevinV]

Perhaps you have been berthed next to some selfish idiot using an angle-grinder?

Good call, it doesn't take much to make a hell of a mess (I did it to my own white car once)

 

[sailoppopotamus]

Perhaps you have been berthed next to some selfish idiot using an angle-grinder?

Or stupidly drilled out a few rivets out of your mast without realizing the implications this would have for your own deck. Ask me how I know, my boat is covered in similar rust stains As far as I know nothing can be done other than to wait for them to rust themselves into non-existence while periodically cleaning the stains with oxalic acid.

 

[AngusMcDoon]

Or stupidly drilled out a few rivets out of your mast without realizing the implications this would have for your own deck. Ask me how I know, my boat is covered in similar rust stains As far as I know nothing can be done other than to wait for them to rust themselves into non-existence while periodically cleaning the stains with oxalic acid.

You can do something about them, but you probably won't like the solution. Y10 or oxalic acid will temporarily remove them, but they come back. A permanent way to get rid of them on non-textured gelcoat is to sand with minimum 1200 grit wet and dry and polish the shine back with Farecla polishing compound. Small areas can be polished by hand. Don't worry about sanding through gelcoat, you can't on flat areas with 1200 grit before you arm falls off in pain, but take care on external corners. The amount 1200 grit removes is tiny, but it's enough to take the small speck of metal away.

Textured gelcoat is more of a problem. You can sometimes scrape the metal speck away with the tip of a scalpel blade,

 

[ChromeDome]

Oxalid acid often removes rust stains.

Available everywhere. Exspensive as boaty products, cheaper for household use - same stuff inside

 

[sailoppopotamus]

Oxalid acid often removes rust stains.

Available everywhere. Exspensive as boaty products, cheaper for household use - same stuff inside

It does, but if you have microscopic specks of iron/steel embedded into your deck, like I do, oxalic acid is only a temporary solution. You'll remove the stain and it will keep returning until there is nothing left to rust.

 

[rogerthebodger]

You could also use hydrochloric acid to remove rust on steel

wash off with lots of water afterwards

 

[Hoolie]

Hydrochloric is a much stronger acid than oxalic. Is there any reason why it can't be used on gelcoat? Well rinsed off after use of course

 

[rogerthebodger]

Hydrochloric is a much stronger acid than oxalic. Is there any reason why it can't be used on gelcoat? Well rinsed off after use of course

I use it on any rust on my steel boat and it does not effect the epoxy paint the boat / deck the boat is painted with

 

[chris-s]

Our last boat seemed to be blighted by little rust specs. As mentioned, repeated Y10 or oxalic until they are no more. Some of the larger specs may be able to pick out with a pointer scribe.

 

[Poignard]

I don't know if this would work but what about trying a powerful magnet to get the bits out?

I had a bit of metal extracted from my eye decades ago using a powerful magnet.

 

[Rhylsailer99]

Once after foolishly sawing a chain on my deck I though I had wrecked the topsides. There was rust spots everywhere, but a few wash downs with a weak solution of oxalic acid and they soon vanish.
It might take a few times for them to rust into nothing.

 

[Concerto]

You could have berthed downwind of a metal working place or scrapyard. Metal particals can be picked up by a strong wind and dropped some distance away.

 

[penfold]

You could have berthed downwind of a metal working place or scrapyard. Metal particals can be picked up by a strong wind and dropped some distance away.

Also a railway line; train brake dust does this also.

 

[bats]

I think I know the answer. I anchor a lot. The anchor chain is rusted around the 30m mark. The rust extends about 5m either side. The manual windlass probably throws off specks of rust and the wind spreads it around.

Solution - re-galvanising, although one company was reluctant to 'contaminate' their bath. New chain? There is a total of 60m of chain so, at 30m, end for ending is not going to help. Or keep getting exercise with cleaning the decks/cabin top?

 

[rogerthebodger]

Cleasn off excessive rust off the anchor chain by draging it behind a car don a dirt road.

 

[bats]

Solution - re-galvanising, although one company was reluctant to 'contaminate' their bath.

Not an option - re-galvanising would not properly coat the links where they make contact.