Identifying if my hull is Corten?

[Asa Hammond]

How can I identify if the steel in my boat is corten or not? I want to repair it with the correct steel plates that are the same steel.

Thank you.

 

[bajansailor]

Could you maybe post some details and photos of your boat please?
Somebody on here might recognise the design (or is she very much a 'one off' design?).

Can you also post some photos showing the areas that need to be repaired please? It would be useful to see what condition they are in.
Do you know how thick the plate is?

 

[kapnD]

The HIN number will identify the builder, whom you should contact for that information.

 

[Asa Hammond]

lots more detail is at my previous thread on the boat: 42 foot steel round bilge sailboat scantlings https://www.boatdesign.net/threads/42-foot-steel-round-bilge-sailboat-scantlings.67826/

 

[BlueBell]

And who will be doing the repair work, you?
If not, ask the people doing the work.

 

[Asa Hammond]

Yes, I will be doing the repair / ordering the materials.

 

[BlueBell]

And how many square feet of plate will you be replacing?

 

[Asa Hammond]

Well, as few as possible. I am not sure if I would have an issue putting mild steel in a corten boat, or corten in a mild steel boat. Its not a cost issue, I want to have a strong hull. The thickness is 3mm. Are there any missmatch issues? Should I just put Corten plating in no matter what with filler rod that is low alloy (er80s etc)? Anyone have direct experience with this?

 

[BlueBell]

Well, as few as possible.

Brilliant!
Best of luck.

 

[Asa Hammond]

Thank you for all your help!

 

[jehardiman]

How can I identify if the steel in my boat is corten or not? I want to repair it with the correct steel plates that are the same steel.

Thank you.

lots more detail is at my previous thread on the boat: 42 foot steel round bilge sailboat scantlings https://www.boatdesign.net/threads/42-foot-steel-round-bilge-sailboat-scantlings.67826/

Given the age, appearance (corrosion is not the right color), and manufacture date/location it is unlikely that the original construction material was COR-TEN (TM). Original COR-TEN plating can be identified by sectioning and metallographic inspection and testing; including X-Ray fluorescence/spectroscopy. Today most "corten" steel of your thickness is ASTM A606 Type 4. Realistically, painting "corten" actually causes more more pitting issues as it is a "weathering" steel not designed for coating or cathodic protection due to the high copper and manganese which gives its lighter weight and higher yield.

Edit to add: Note that 606 Ty 4 overlaps ASTM A588 at 3/16 so depending on application either could be specified.

 

[comfisherman]

If it's a colossal pain in the backside to weld its probably corten. Running joke is if you weld it and feel like you somehow forgot to weld its probably a Corten hull.

 

[Asa Hammond]

I believe it is corten because of some marketing material of a 5 year later boat from the same builder and designer (Henk Tingen, KOK boatyard netherlands) that was marketed as being made from corten.
What lab would I send a sample to? How can I get an expert to run the right type of metallographic inspection and testing?

 

[Asa Hammond]

Are there examples of corten steel hulls that go unpainted? I thought that was just for land usecases?

 

[comfisherman]

It's good but it isn't that good.