Steel Boats and Welding

[haidan]

Originally Posted by Yachts66

Good, because it's not supposed to insulated below the water line!! One of the primary purposes of insulation is to eliminate condensation, which only happens above the water line!

Thomas

I'm a big fan of that blown in poly foam, I brought mine down below the water line, not all the way, I still have a bilge that's bare painted hull, which does collect a fare amount of condensation when it's open to the rest of the boat. My foam comes down to the floor board level, which is about a foot or so below the water line. As I said if the bilges are open to the warm boat atmosphere then I get a fare bit of condensation down in the bilge. Maybe I'm taking this out of context but condensation happens everywhere on the boat, that is anywhere where warm water carrying air meets colder steel hull/frames, below the water line or above. Up here in the PNW I would say that condensation happens more readily above the water line than below. Well, in the winter anyway when the hull temp above the water is air temperature cold, say around freezing, whereas the water is several degrees above freezing. I've found that the lips around my hatches and any small little bits that got missed when I foamed drip more water by far than I get collecting in my bilges.

[boden36]

You should have no problem apart from the distortion issues previously mentioned.
If a plate is pitted but not penetrated, then you can just double it. So long as no oxygen can get between the plates, there is absolutely no chance of corrosion. I recently opened a pipe I had welded shut 25 yrs ago and it was as new.
Regards,
Richard.

[shorebird]

Grinding steel before painting may not give the adhesion that blasting will, since proper blasting will give a better "micro-edge profile" on the steel, giving the paint a better anchor.

[Yachts66]

1/4" plate is awful thick! How big is this boat? The other option is to cut out the bad area and weld in a new plate, which would be a lot less expensive I think and quicker!

Thomas

[Matt sachs]

Normally I would but part of it was under the mast post and would be a PITA to get at.

[Matt sachs]

It's a 50 ft Roberts. The keel is 5/16. The first Chine is 1/4. The second Is 3/16 and the third is 1/8. The keel plate is 3/4.

[S/V Alchemy]

Yikes...Good luck with the repair.

[Boracay]

Is it possible to weld in a plate on the inside, with welding all round the edge? Then fill the hole from the outside with as much weld as seems practicable and grind smooth.

Even if it had to be shaped to fit it's steel thickness that you want. A decent thickness can take many years o rust through, even longer if you can get some sort of decent coating on it.

[MacG]

That may be, but it is far from wisdom.
Re: onesided welding: it depends where? Keel and bilge sections are welded outside & inside although there are methods to do the traject in a single run. Depends totally on the skill of the welder.

[PaulyG]

I love these welding questions, they get so many replies.
I am Boilermaker by trade and have been welding for 15 years.
Boracay has pretty much hit the nail on the head. All of the boat must be easily accessible from the inside for maintenance and inspection. Van de stadt has some really good modern designs with minimal internal frame work.
You would neeed to buy yourself an air compressor and needle scaler as well as a grinder and wire brush/wheel for clean up and rust removal. It is fairly quick and easy. It takes longer to remove the internal fixtures than what it does to do the repairs generally.
Steel, welding consumables and required tools are relatively cheap. As far as DIY goes it is achievable.
If you learn to look for the tell tale blisters and bubbles very few of the repairs will actually require welding. When looking at a boat you would brobably only see 20-30% of the rust that is there on first or second inspection.
At the end of the day stick with what you know, I have a steel yacht because I am a Boilermaker

[PaulyG]

Originally Posted by Boracay

Is it possible to weld in a plate on the inside, with welding all round the edge? Then fill the hole from the outside with as much weld as seems practicable and grind smooth.

Even if it had to be shaped to fit it's steel thickness that you want. A decent thickness can take many years o rust through, even longer if you can get some sort of decent coating on it.

It is possible, what you need to remember is that more welding means more heat. This in turn means more distortion. A small area would be ok, a large area is not such a good idea. The process of building up a surface with weld is known as "pad welding"
All joins need to be "butt welded" that is edge to edge not over layed. Overlayed layers sweat and rust from the inside out.

[S/V Alchemy]

Originally Posted by PaulyG

At the end of the day stick with what you know, I have a steel yacht because I am a Boilermaker

Finally, something we can all agree about.

[Matt sachs]

Thanks for the tips guys. Fortunately (or unfortunately) I have every tool one could need for boat building, and about 50% of the skill needed to use those tools. But that number is increasing everyday.
The only place on the inside of the hull that dosent have very easy acess is the area I was asking about. There is an I beam spanning the forward keel area that the mast post sits on. Its all fixed up now. I'm going to clean it up and coat with 3 coats of amercoat 240 the next time we get some warm weather

[Yachts66]

Curious why 240? 235 is generally less expensive an works great in most applications.

Thanks,

Thomas

[xymotic]

I know nothing about steel/welding. I also know very little about FG, and in fact every fiberglass project I've attempted has been an expensive, crappy looking mess. My very first weld, was also crappy looking, (so I bought a better grinder ) but not counting the equipment costs was actually pretty dang cheap. And I figure the equipment will last a good long time and I can sell it later for what I paid for it, unlike epoxy.

OK, so here's my dilemma. I'm self-taught at pretty much everything. I can pick up a book and learn how to weld, but I always doubt myself and wonder if I could do it better. So how to I get a basic welding class without taking a year(s) long get certified and get a 'career' community college course?