Why is this exposed steel not rusting?

[peter57]

Originally Posted by Captn_Black

Can confirm

Off topic, But I have a junk as well.

[Captn_Black]

Originally Posted by peter57

Off topic, But I have a junk as well.

Ahoy! I see you too are a man of culture

I created a junk rig thread here a while ago if you want to pop by and say hi.

[peter57]

Originally Posted by Captn_Black

Ahoy! I see you too are a man of culture

I created a junk rig thread here a while ago if you want to pop by and say hi.

I seen it and your YT channel.
Here is a pic of no rust using the burr method.


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[Captn_Black]

Nice, I've also been looking into the possibility of a bowsprit and jib. Would make sailing to windward easier in light wind.

[Scorpius]

Scorpius was launched in 1982. After ALL the steel fabrication was done (hull, deck and house) she was completely, inside and out, sandblasted and zinc flame-sprayed (done with a cross between a paint sprayer and a welding torch - effectively hot dip galvanizing EVERYTHING!). Then, inside, an inch and a half of foam was sprayed in down to the top of the box keel. In the close to 40 years since then, there is, and has been, almost no rust anywhere except where modifications have been done. Anywhere I've removed foam inside to do something, the steel behind is absolutely pristine. It's really quite remarkable.


The only place it has been a problem (and it was a BIG problem at the time) was outside below the waterline. It acted as sacrificial zinc and caused the copper paint to slough off in sheets. I called the paint rep for advice and he said I could sandblast it off - which would be a very slow and expensive job because that stuff is really stuck on there and would also probably warp the plates from the heat generated - or I could just wait until it all sacrificed itself and put a new bottom paint system on - which I did. It's been great since. If I ever built a steel boat (which I won't as I'm 73 and quite happy with Scorpius) I would for sure have it flame-sprayed.

[peter57]

Originally Posted by Scorpius

Scorpius was launched in 1982. After ALL the steel fabrication was done (hull, deck and house) she was completely, inside and out, sandblasted and zinc flame-sprayed (done with a cross between a paint sprayer and a welding torch - effectively hot dip galvanizing EVERYTHING!). Then, inside, an inch and a half of foam was sprayed in down to the top of the box keel. In the close to 40 years since then, there is, and has been, almost no rust anywhere except where modifications have been done. Anywhere I've removed foam inside to do something, the steel behind is absolutely pristine. It's really quite remarkable.


The only place it has been a problem (and it was a BIG problem at the time) was outside below the waterline. It acted as sacrificial zinc and caused the copper paint to slough off in sheets. I called the paint rep for advice and he said I could sandblast it off - which would be a very slow and expensive job because that stuff is really stuck on there and would also probably warp the plates from the heat generated - or I could just wait until it all sacrificed itself and put a new bottom paint system on - which I did. It's been great since. If I ever built a steel boat (which I won't as I'm 73 and quite happy with Scorpius) I would for sure have it flame-sprayed.

Was the engine Earthed to the hull?

[RaymondR]

The US Coast Guard built some cutters from galvanized plate and blasted and metal sprayed all the weld damaged areas.

[Dougtiff]

Year's ago i was working in Jetta, Saudi Arabia, a German construction company was building i believe the largest R O plant in the world, mostly built out of Monel steel, one of the welder's was building a 50 ft. Sail boat out of Monel, as he had been able to include a order along with the Mega order for the plant, so got one hell of a deal, he was building the boat "MONELA" after working hour's on his own time, [now that's a good employer], no paint on the metal, often wonder how it turned out.

[peter57]

Originally Posted by Dougtiff

Year's ago i was working in Jetta, Saudi Arabia, a German construction company was building i believe the largest R O plant in the world, mostly built out of Monel steel, one of the welder's was building a 50 ft. Sail boat out of Monel, as he had been able to include a order along with the Mega order for the plant, so got one hell of a deal, he was building the boat "MONELA" after working hour's on his own time, [now that's a good employer], no paint on the metal, often wonder how it turned out.

Maybe lots of barnacles under the water line.

2 boats ago I had one of Huon pine timber, S&S 43' one-off design, the floors were Cu-sil-mon bronze but the rest of the metal on her was Monel, like the wheel, stanchions, propellor, prop shaft, pulpit, push pit bow roller, ect. ect. she was also splined and the planking screws where Monel and all of it was like the day it was fixed on in 1961, it is an amazing metal.

[hpeer]

There was another libel boat built sponsee but some copper research outfit. Some papers were written on her.

She was advertised here for a couple of years and recently sold. Rio Dulce I think. Wooden spars, don’t know why.

[Mauro47]

It could be the original primer coat of vinyl inorganic zinc, 30 years ago this was a popular and extremely effective steel primer for inboard and topside surfaces.

[Coltrek]

Definitely zinc

[GrowleyMonster]

What they said. What you are looking at is not steel. The steel is underneath, protected by whatever is on the surface, be it zinc or what have you. Still, best wire brush, feather the old paint, and spot paint that area with 2 or 3 coats of epoxy based enamel soon.

[Flynsail1]

I had a friend who built a 40' steel boat in California and it had an alloy with nickel in it and it never rusted. It was built in the '80's

[merrydolphin]

Hard to tell from the photo, but sort of looks like galvanized steel.
If so, there is your answer. If it has little patchy lines going in different directions, it galvanized.