SS and Pit Corrosion

[lewisboats]

Does anyone know if 304 SS suffers from Pit corrosion in fresh water?

Steve

[duluthboats]

Hi Steve,

304 is also known as 18-8 because it has approximately 18% chromium and 8% nickel. It will corrode under harsh conditions but is used commonly in marine environments.

Edited to add I don’t think it is recommended to use 304 screws in wooden boats below the water line, I would use Monel.

Gary

[DanishBagger]

Couldn't one just upgrade to 316? I mean, instead of going monel (=$$)?

[dimitarp]

The 316 is better than 304, but monel is better than 316

[DanishBagger]

True, but isn't much more expensive?

The reason I'm trying to make that point is that if money weren't an object, the thread starter propably wouldn't have asked if he could use 304. Or, at least that's how I read it - it wouldn't be the first time I was wrong.

Of course,he could also use silicon bronze, or titanium

(wishing I could afford titanium myself)

[dimitarp]

I think that the price of 316 i not defferent from 304. But titanium is more expensive

[DanishBagger]

Lewis,

I found this link:

http://www.assda.asn.au/asp/index.as...34299&id=56951

The thing is, it seems to be able to hold up, but the moment you introduce electricity (from a stray wire, for instance) things begin to happen, as I understand it. Crevise corrosion is one of my real fears about this.

Caveat: Please dotakethis with a grain of salt, I'm certainly not very experienced in boatbuilding, nor have I owned tons of boats. However, my boat will be built with bronze screws below the water line, bronze screws in the gunwhale and so forth. Onlyin places where I either cannot get bronze for the application, or where it is _very_ easy to exchange will I have stainless steel. Hell, my padeyes will be titanium.


Is it a trailer sailer? Wood-epoxy? "straight" wood?

I mean, if it's a trailer sailer, and all the fasteners are made the way the gougeon brothers do it (the screws are inserted into a plug of epoxy), I can't see any problems arising.

On the other hand, trailing a boat on the road, getting road salts up there, suddenly you will have a saltwater environment.

Anyways, if I were you, I would use the best you can afford, when it comes to fasteners below the waterline. Skimp on something easily changed instead.

[lewisboats]

The main fact is that I can 3/4" by what ever length I want of 304 bolts and nylock nuts for free...very much an incentive to use them. I would be using them on a small (11.5 ft) Stitch and Glue sailboat with a simple plate steel keel (maybe also 304 SS) with a jack knife style dropdown swinging section. The keel will be mounted to a wood fairing pad with the bolts welded on top and thru bolted to floor timbers. The only electrics would be battery powered, closed loop stuff, no common ground.

Steve

[lewisboats]

Originally Posted by DanishBagger

Lewis,

I found this link:

http://www.assda.asn.au/asp/index.as...34299&id=56951

The way I read it...I should be in the clear. This all relates to salt water, it even says you should rinse your 304 off with fresh. Guess I'll be rinsing it off with every outing. In fact...cleaning my stainless might become an obsession

Steve

[DanishBagger]

Indeed, that's how I read it as well, Lewis.

About the electricity, I was talking about other's, but seeing how small it is, I assume it would get out of any water fairly often.

Good luck with it

[MikeJohns]

Originally Posted by lewisboats

Does anyone know if 304 SS suffers from Pit corrosion in fresh water?

Steve

If it is in wet wood fresh water or otherwise, yes it will pit and crevice corrode.