whicht type of steel

[Lexluthor]

hi guys,

Upon inspecting the hull of my recently purchaded steel sailingboat i discovered rust in the usual places, under the toilet area (a strip about 7x40 cm) and the anchor chain locker is a gonner also.

I allready have cut out the bad pieces, measuring the sound plate i have a thickness of about 4 mm, what type of steel should i purchase to make these patches (i shall have the welding itself done by a pro but i would cut the patches to size myself), i have a choice of cold or hot rolled plates or prepainted. The outer hull will be shot blasted for a new painsystem, inside the hull this will not be done because its in good shape.

Thanks for the tips guys,

[Brent Swain]

Common mild steel is all you need. There are no real advantages to other steel types.

[Lexluthor]

this gets confusing, should i weld in plain mild steel, what about patching things up with corten?

< mod note: sorry; posts regarding Brent Swain / Origami thread have been deleted since they don't have to do with your thread >

[Wynand N]

Originally Posted by Lexluthor

this gets confusing, should i weld in plain mild steel, what about patching things up with corten?

If your hull is mild steel, stay with it.
Corten is in my view a bit over rated and costly for steel boatbuilding and the bit of copper contend in it to little to be of any help with barnacle prevention and the steel get anyhow painted making that property obsolete.
It do have a bit of stiffness to it because of the carbon content and should be welded with E7018 (low hydrogen) electrodes which is problematic for the novice. It need to be in a hot box and absolutely dry, buzz box wont work nicely since you need at least 72 OCV (open circuit voltage) machine to have a decent go with 7018.

Lastly, a chain is only as strong as its weakest link - Corten patches will no nothing structurally in strength.
Hope this is helps a bit.

[gonzo]

If the hull is mild steel, that is the proper patch to use. It is also easier to work cold to match the shape of the repair.
Dskira: you are hijacking a thread with your ranting. Why don't you give Lexluthor some relevant advice instead? He is needing help.

[rugludallur]

Originally Posted by Lexluthor

hi guys,

Upon inspecting the hull of my recently purchaded steel sailingboat i discovered rust in the usual places, under the toilet area (a strip about 7x40 cm) and the anchor chain locker is a gonner also.

I allready have cut out the bad pieces, measuring the sound plate i have a thickness of about 4 mm, what type of steel should i purchase to make these patches (i shall have the welding itself done by a pro but i would cut the patches to size myself), i have a choice of cold or hot rolled plates or prepainted. The outer hull will be shot blasted for a new painsystem, inside the hull this will not be done because its in good shape.

Thanks for the tips guys,

Like others have stated, if the boat is mild steel just patch with mild steel. If the hull is marine grade (Grade A) you should patch correspondingly, especially if you sail in colder waters and if it's a larger vessel (see Brittle Fracture).

Jarl
http://dallur.com

[gonzo]

In cast iron repairs, nickel rods are usually used to prevent stresses. Does that work on hull repair or does it create an electrolisis problem?

[TwoByFour]

Originally Posted by gonzo

In cast iron repairs, nickel rods are usually used to prevent stresses. Does that work on hull repair or does it create an electrolisis problem?

I've not tried it, but it is clear that Nickel is more noble than steel and thus I would expect the steel to sacrifice itself. I imagine that it would be similar as having stainless welds on an otherwise regular steel hull - It probably would not cause any problems though, if the repair area was to be properly coated afterwards.

Is there a reason to worry about stresses in repair welds any more than if you were welding together a hull from scratch?

Carl