Stainless Steel Yacht

[jamie N]

Just having had a swift browse (not swift enough actually), through the thread here about 'Steelboats', corrosion is mentioned somewhat frequently.
What's the reason for not having Stainless Steel as the build material?

 

[Iliade]

Crevice crack corrosion, amongst other issues.


Corten is probably the 'best' steel for boats.

 

[dom]

Corten is probably the 'best' steel for boats.

£££££££££££££££££££££££

 

[weustace]

I did meet a couple in Yarmouth (IoW) last season in a beautiful looking 45' (ish) boat. I enquired what it was made of, and was very surprised to be told it was SS. I asked in some incredulity and it was confirmed... I still don't know if this was a wind-up that I somehow missed the humorous aspect of, or whether it was actually true!

 

[sailorman]

Wasnt there a Aussie yacht called "Gelignite" hull formed by explosion, a vauge memory from a yotti Mag mebe 40 yrs ago

 

[sarabande]

Yepp, explosive formation. usually used in clever military devices where you want to fix two metals together without welding into a special cylindrical or conical shape.


IIRC there was a New Scientist (black and white !) article on the process.

 

[JumbleDuck]

Wasnt there a Aussie yacht called "Gelignite" hull formed by explosion, a vauge memory from a yotti Mag mebe 40 yrs ago

Yup. It was an Australian design by "Dynamite" Don Richardson in, I think, 1989. There is a picture, which I better not embed, at https://www.gettyimages.co.uk/detai...-with-crew-squad-leader-news-photo/1080214970

Basically they made a roughly shaped hull, all flat surfaces and straight seams, lowered it into a concrete mould in the ground, filled it with water and set off an explosive charge in the middle. The charge creates pressure, the water transfers it to the rough shape and the aluminium is forced into the shape of the mould - I expect with a bit of springback.

 

[DownWest]

Yepp, explosive formation. usually used in clever military devices where you want to fix two metals together without welding into a special cylindrical or conical shape.


IIRC there was a New Scientist (black and white !) article on the process.

Also used in a joining strip for the superstructures of steel hulls with ally tops. You can weld to both.

 

[DownWest]

£££££££££££££££££££££££

When I was building steel woodstoves, I managed to buy Corten 4mm for not much more than plain mild steel?

 

[noelex]

I have seen a couple of stainless steel yachts. They were not without problems, but no boatbuilding material is perfect.

I once had dinner on two boats that were rafted up together. They were identical, from the same builder, but one was conventional steel and one was stainless. The stainless yacht had to replace the entire deck, but this was originally covered in teak. Wood over metal is rarely a great idea.

 

[Ladybirdgaffcutter]

There's a totally copper yacht (or was it bronze?) out there somewhere, it was looking a bit green in the photo I saw...everything corrodes..

 

[dom]

When I was building steel woodstoves, I managed to buy Corten 4mm for not much more than plain mild steel?

The trouble with Corten steel, as I understand it, is that it’s not that great in marine environments owing to the fact that the combined hygroscopic nature of salt and the high chloride ion content of seawater can damage the natural patina which protects the steel’s surface. Which in turn either directs one towards quite specialist steels in terms of exact composition, or back to pricey surface coatings. Happy to be corrected if this is not the case.

 

[DownWest]

The trouble with Corten steel, as I understand it, is that it’s not that great in marine environments owing to the fact that the combined hygroscopic nature of salt and the high chloride ion content of seawater can damage the natural patina which protects the steel’s surface. Which in turn either directs one towards quite specialist steels in terms of exact composition, or back to pricey surface coatings. Happy to be corrected if this is not the case.

Yes, I heard that too. If it was that good, it would be worth the bit extra in the overall cost of the hull. Reality is, you still have to protect it with the coatings.

 

[rotrax]

The trouble with Corten steel, as I understand it, is that it’s not that great in marine environments owing to the fact that the combined hygroscopic nature of salt and the high chloride ion content of seawater can damage the natural patina which protects the steel’s surface. Which in turn either directs one towards quite specialist steels in terms of exact composition, or back to pricey surface coatings. Happy to be corrected if this is not the case.

I fail to understand why anyone would imagine that Corten steel would not require protecting with coatings. AFAIK it is just a slightly more corrosion resistant steel.

I can assure you, as the owner of a Corten steel boat built in 1986 that it still rusts, even with protective coatings.

I have just repaired 4 window apertures and a cockpit side where severe corrosion and holes had appeared.

Due to bad practice when built 34 years ago. In the best tradition of proper repair work, the fault has been repaired and the cause of the fault removed.

Hopefully, the fault will not re-appear!

 

[JumbleDuck]

I fail to understand why anyone would imagine that Corten steel would not require protecting with coatings. AFAIK it is just a slightly more corrosion resistant steel.

Corten is widely used without any coatings - it's a weathering steel, and that's the point, really.

See: North, Angel of the

 

[dom]

Corten is widely used without any coatings - it's a weathering steel, and that's the point, really.

See: North, Angel of the

True, alongside many art pieces in the 1990s when its tanned look was de rigueur. Also widely used in ind eng.

But I seem to recall it is contraindicated within two miles of the sea for the reason that marine environments break down the steel's protective patina allowing good old rust to take hold. Once again, happy to be corrected.

 

[JumbleDuck]

But I seem to recall it is contraindicated within two miles of the sea for the reason that marine environments break down the steel's protective patina allowing good old rust to take hold. Once again, happy to be corrected.

It's used for a lot of shipping containers, but I suppose those are painted.

 

[lw395]

Corten is widely used without any coatings - it's a weathering steel, and that's the point, really.

See: North, Angel of the

I have seen that, and verily it doth rust.

 

[dom]

It's used for a lot of shipping containers, but I suppose those are painted.

You're right: shipping containers tend to be either single-use cheapo steel jobs, or high quality ones fabricated from corten steel. Shipping containers spend a lot of time inland, but even then the average life is about 10 years before they're sold-on to non-premium shipping Co.s or other users.

The ones used for site huts, storage, etc are invariably corten and with a good wash-off can last another 30 years or so inland. So that's 40 years in total which is not bad considering the bashing they get.

It's a great product, just compromised in a marine environment. Perhaps shipping containers could be made of stainless steel?

 

[JumbleDuck]

I have seen that, and verily it doth rust.

That ith the point. It ruthtetht, then it thtoppeth ruthting, thankth to a thuperfithial thurfacthe layer.