Stainless steel / Aluminum

Stainless steel / Aluminum

We are building at this moment yachts between 25 and 100 meter using ordinary steel and steel constructions. We planned to build one yacht with stainless steel.

This because of the following reasons:

Stainless steel we can use 6 mm comparing to 8-10 mm normal steel
No painting
Less maintenance
No big change in the current logistics and way of working
Stainless is a local product of Indonesia and sheep in comparing to Aluminum.

Who has an opinion, what are the + and – in your opinion.

Hendrikus

 

The biggest problem with stainless steel is crevice corrosion, specially at the welds. You should check with a metalurgist. In the USA the best I've worked with is Q Metalurgic in Florida.

 

stainless steel boat

I have worked with stainless a lot and believe that some people with advanced sheetmetal/ welding/ panel beating / polishing skills could build a very goog boat from sheet thicknesses up to 4mm. Stainless has servere shrinkage characteristics in the weld zone not to mention oxidadation. Basically the more you weld your boat the smaller it gets. Once the hull is enclosed and is damaged, the repairers must have access to the inside of the repair in order to shield the heat zone with argon and then applie a dolly for stress relief treatment. So I believe its possible to build in Stainless but would cost much more than steel.
Note A good stainless job is taken for granted, a bad one is an eye sore.

 

Better to keep with ordinary steel, it is something you can get at any ship/boat yard and even metal fabricators ashore usually have a grade which is compatible with your original material. Besides it doesn't take too much to weld ordinary steel, just practice and the right welder.
Stainless and skilled stainless steel welders are not as readily obtained, plus the added cost of inert gas shielding and the not so little problem of crevice corrosion common in poorly made stainless joints.
As for worrying about maintenance -- you still have barnacles and bottom coat to worry about, and the deck and ........... you get the picture, you will always want to do something in the way of coating. Save the stainless for the galley counter and maybe the fresh water tank -

 

I just read an article on use of stainless steel on submerged areas. It sounds like a BAD IDEA. Salt water and moving water interferes with the passivisity of the stainless, making corrosion unpredictable and portentially aggressive. Obviously for a hull, we are talking about a huge area, but active stainless on a scratch on the hull bottom will lose electrons to the passive stainless on the relatively larger hull surface and rapidly start to destroy the hull where the scratch was. I think they said that stainless loses it's passivisity over 3 months

 

Stainless steel vessel?

Hi Mr Builder

I would be very interested to see what life a large S/S vessel will have

S/S work hardens, that is to say when the material is put under stress loads as in a vessels hull it continues to gain hardness to a point where it will no longer flex and there fore must fail eg S/S rigging

The same properties that prevent corrosion also reduce ductility

Sir i am sure you have more expertise than i and would very much appreciate understanding why S/S construction material will not eventually fail

cheers

lyle