Rusty Stainless steel

[DAKA]

My grab rails have patches of light rust on them, it wipes off with a sponge or even your hand but its a bit unsightly and adds an extra 1/2 hour on to the washing.

I am currently berthed very close to the sea and I think the waves are pounding the shore and salt spray is being blown onto my boat.

I assume others have had this problem ?, any tips on how to avoid it , anything I can spray onto the rails to protect them.

The stainless horn is allowing a brown streak to form under it on the fibre glass.

 

[Nick_H]

polish the stainless

 

[Firefly625]

paint it with silver hammerite

 

[npf1]

Polish the stainless then wipe over some Rain-X, which is the stuff sold in car accessory shops for windscreens.

 

[VicS]

Possibly the rails are not 316 stainless. If its near welds then its due to the effect of heat on the alloy.

Rust stain from under the horn is almost certainly crevice corrosion. Remove and refit the horn on a bed of sealant so that no water can penetrate the joint.

 

[SAMYL]

Stainless steel isn't.

 

[omega2]

as stated they are not 316 grade, the horn is likely to be the fixings not the horn itself. but can be helped by fixing onto a bed of silicon. non 316 will always stain, best way i have found is polish with auto autosolve, it's a fine paste abrasive, failing that try cif, the kithen pan cleaner, whatever you use repeats will have to be made, or move away from the sea.

 

[DAKA]

Thanks for everyones replies.

Possibly the rails are not 316 stainless. If its near welds then its due to the effect of heat on the alloy.

Rust stain from under the horn is almost certainly crevice corrosion. Remove and refit the horn on a bed of sealant so that no water can penetrate the joint.

You have got me thinking now, the horn and bedding idea is good advice i will do that next.
Now having sorted the horn I am thinking the grab rails are perhaps an unrelated problem, I have had the boat 4-5 years and it has been dowsed in salt water plenty of times without going rusty.

The 'Rust' was red dark brown and wiped off with my fingers as a fine wet powder, under the 'rust' it was bright and smooth as it always has been, perhaps it is red brown mud from the nearby cliff or red lead antifoul that has been sanded off another boat close by ?
But I cant account why the muck only stuck to the stainless grab rail, the horn was clean apart from the brown streak under it on the fibreglass which you have solved thanks Vic.

I recognise the boat at the side of me (more or less) as another forum member but I haven't see him on his boat yet, I will try to find him on here and send a pm to see if he suffers the same problem.

 

[jhr]

I may have this wrong, in which case VicS will give me a sharp rap over the knuckles , but I have been told that stainless steel will rust if the metal added to make it s/s is covered by anything, hence not exposed to the atmosphere, thus allowing the steel to oxidise. My s/s prop gets a faint covering of rust when I clean it up with barnacle remover (dilute H2SO4, basically) when the boat's out of the water. A gentle polish with very fine sandpaper removes this tarnish for the duration and I guess a proprietary polish would have the same effect?

 

[DAKA]

I have been trying to ignore the word Polish that repeatedly keeps cropping up in replies .

I have now spoken to my new neighbour and unfortunately it is a very light rust developing from the heavily laden salt air and he has confirmed metal polish 3M is required.

I have never needed to use metal polish before but I will have to start now.

Thanks again for all your help.

 

[VicS]

Yes stainless steels are protected from corrosion by a film of chromium oxide on the surface. It requires exposure to oxygen to maintain this layer but the oxygen concentration in ordinary seawater etc is adequate. If water is trapped in a small gap its oxygen concentration becomes depleted and crevice corrosion can occur. that is why fittings should be bedded on sealant and fastenings well sealed into the holes. We nearly lost a mast a few years ago when a shroud attachment U bolt failed due to crevice corrosion!

Anything that removes the oxide film will lead to some corrosion until it reforms, which it does fairly readily.

There is a good chance that dakarak's problems with the rails are due to red dust deposited on them now that he describes matters in a little more detail.
If anyone is sanding antifouling dry and creating dust they are a threat to your health and deserve a kick where they wont forget it.

 

[tinkicker0]

I have been trying to ignore the word Polish that repeatedly keeps cropping up in replies .

I have now spoken to my new neighbour and unfortunately it is a very light rust developing from the heavily laden salt air and he has confirmed metal polish 3M is required.

I have never needed to use metal polish before but I will have to start now.

Thanks again for all your help.

just remember never, ever use a wire brush or steel wool to clean stainless.

 

[sarabande]

What about applying some of these clever metal polish bottled stuff so beloved of car owners ? Anything that creates a barrier to the atmosphere will allow the shine through, but stop the rain getting to the metal surface.