Rust in steel Schooner bilge? Some say "run"?

[Boatwright]

Marinette, Wisconsin is on Lake Michigan -- [U]fresh[U] water. Is it still on the lakes? Steel lasts a long time here. Plenty of old, old beat up fish-tugs with 1/8" steel hulls that are still going strong.

Cor-ten steel is a lot like stainless in that the surface layer of corrosion protects the underlying metal. Steel is also easily repairable anywhere with readily available tools and materials.

[Triumphant]

Originally Posted by captlloyd

Well I think that is a mistake on someone’s part. On that size boat I would expect at least 6mm if not more.

we have a 40 foot steel boat, Hull is 4mm, deck is 3 mm and the bottom of the keel is 12mm

[Huron Jewel]

I have been captain of several steel schooners. The ones that come from freshwater can be in very good shape. The ones in salt do ok, but you have to be able to see/paint all of the bilge. I worked on one that didn't get painted before the interior went in and there were some places that the steel was thin because it was completely inaccessible from from the inside, hence no maintenance. That just means welding new plating on sometime. The survey on that vessel showed good but the hull thickness was carefully measured at the frames, so it included the frame thickness as well... Otherwise, like has been said, there are many good things about a steel boat, strength and ease of repair being the main ones.

[AKA-None]

Well I’ve never owned a steel boat but spent many years building and repairing steel ships :-)
You absolutely need to stay ahead of all rust.

Unless you like sitting in a boat yard replacing plate and stringers.

[hpeer]

First there is too little info to go on to give any difinitive answer.

My standard advice before buying a steel boat is this: YOU (not a surveyor) must do a very through out of water inspection of the entire interior of the boat using a strong flashlight, big screwdriver, and ball peen hammer. YOU must be able to get to the entire interior, if you can’t then no one else could either and that is where there will be rust. Infrasound inspections are nice for insurance companies but are pretty worthless for the Owner, BECAUSE rust can develop in very small localized places, a very through ultrasound will be done on a 1’ by 1’ grid and could entirely miss a few bad spots. As noted above look for areas where water can accumulate and or drop in for a long time. Chain lockers and lazzaretts, under sinks.

I’ll take a contrarian view on having the owner do the repair before buying. I would suggest you get an estimate for the repair and deduct from the price. I would want the repair done by myself or under my supervision. I want to know perskannly just how bad it is and authorize any additional work. Frankly I don’t want to trust someone with a motive to go cheap to do the work.

Another place I would check for small localized but deep rust would be within 2” of any Stainless fittings not welded to the steel. Again I have a contrarian experience, but that experience tells me this is a prime spot for rust.

Don’t be too afraid of replacing plate. I’ve had to do some and it’s not terribly bad. As long as you can get to both sides. If you have to start ripping out furniture, then no.

Our small boat has mild steel chain plates, they always streak. On the big boat the origional owner replaced the mild steel chain plates with stainless. No rust. I’m thinking of doing something similar on the small boat.

I’m guessing it’s a Colvin Gazzell? I’ve seen some Colvin boats built with pretty light gage steel. We looked at this one about 10 years ago. At the time we were told by the origional owners it was 10 gage steel.

https://www.yachtworld.com/boats/199...ketch-3079240/

[Tarheelrod]

I have had a very long and busy day and only now have been able to grab my IPAD and see what replies have come in. I was so pleased to see this many folks take the time to weigh in on my questions. I can’t thank you enough!

[mako]

Hi Rod, I bought a 40 year old steel boat of 65ft. I would say that when you own your own steel boat, it will be wonderful because you are maintaining it properly.

However, when you are buying a used boat, one sitting neglected like you describe, then it is assumed that there will be corrosion problems that need to be corrected, either through local sandblasting or by cutting out and replacing plating. Do NOT add patches on top of corroded steel.

I had a couple of small sections that needed to be cut/replaced and the yard bill was $5k. That was years ago. But there was bigger work needed that I delayed, so the bill should easily have been $15k+. You need to assume something like this with your boat as you go into it.

BTW, 1/8" steel plating is very thin. It is acceptable, but very thin. There is basically no room for corrosion in such a size. And if you are planning remote bluewater cruises then I would look for at least 3/16" hull thickness in a 40ft boat.

[RaymondR]

Patching steel hulls can be very fast and very cheap. During a hull refit on my old steel boat the welder and I did one patch in about 35-40 minutes.

Since most of the problems were caused by water pooling in stringers and stringer frame intersections I crawled around in the bilge with an electric drill, a scraper and a chipping hammer and when I found corrosion chalked around it and drilled 1/8" holes at the corners, I usually tried to encompass the corroded spots inside triangular markings as it's easier to measure and mark out the patches.

Most people cut the hole then make a patch to fit however it is much easier and quicker to cut the patch using measurements defined by the drilled holes to get a slight oversize patch then tack weld the patch onto the hull and using a 1 mm thick cutting disk guided by the patch to get a perfect patch/hole match with a 1 mm gap all around.

The next bit's more conveniently a two person job.

Cut the tacks off the patch to get rid of the waste and fit one corner of the patch into the hole and tack it in place. A couple of pieces of 1 mm or so wire bent around the edge of the hole will help in getting the 1 mm gap right.

You work your way around the patch putting small tacks and using a straight edge to get the patch perfectly placed. We used a piece of 1 1/4" x 1/4" flat bar to pull the edges down by tacking the 1/4" edge onto the plate and levering the patch up or down to get it perfectly even with the surrounding plate. Bending the tack backwards will break it free.

After you get your patch properly placed you go inside and run a bead of weld all the way around the 1 mm crack and then go back outside and grind a V groove down to the inside weld.

Fill the V groove and grind it back to the level of the plate and you will have a good, fair patch with a fully penetrated weld.

If I had not gotten so old and lazy and been able to keep up with the maintenance I'd have built another steel boat rather than buying the plastic one I have now - no other material gives you the security of steel.

[GordMay]

I haven’t owned a steel boat but ... I’ve worked on a number of them, whose owners didn’t know diddly squat about them, and I can corroborate ausnp84's (& others) advice.

[RaymondR]

One of the tricks I used in places where I could not remove or alleviate the trap was to put anodes in them.

I would put a 90 degree bend in the end of a piece of 12 mm x 3 mm alloy flat bar, clamp the short leg against a frame, drill through the alloy and frame with a 1/4" drill, and rivet the alloy to the frame, with the long leg lying along the bottom of the water trap, with a short piece of 1/4" alloy rod.

[mako]

Tatheelrod22, word of advice. Find the deepest, darkest, nastiest corner of the bilge. Usually deep in the forefoot under a tank, or below the packing gland. If you investigate and it's filled with what was once hot melted tar, then run for the hills. Sleazy scam artist seller.

Only a fool would buy a boat like that. Don't ask me how I know

[Delfin]

Other than verifying the use of Corten steel and access to all bilge areas that can be exposed to water, I wouldn't worry about it if you like the boat. Corten is stronger than mild steel, so 1/8" sounds ok to me. Delfin is built of mild steel, weighs a lot more than this vessel and is 1/4". If Corten, they would have used 3/16".

I would ask the seller to blast, prime and coat the area in question. If they just slap some Rust-Oleum on the area, it won't last long.

Just FYI, but Corten is formulated to be used where paint maintenance can be a problem. Ideal for boats.

https://en.m.wikipedia.org/wiki/Weathering_steel

[hellosailor]

I can appreciate an owner NOT fixing corrosion. Consider, if the buyer has a survey that says "Shows signs of recent repairs, exact extent of problem cannot be determined". That's what you get if it has all been nicely refinished and done. But by leaving the rust visible, it can be surveyed, can be evaluated, and the buyer gets to see what the problem is, before the seller turns around and pays for the repair job. And, different buyers might want different repair jobs.

Coal tar epoxy?? Coal tar is one thing, epoxy is another. Sounds like mixing fresh sushi and lean hamburger: A perfectly good waste of two good materials combined that way.

Some buyers might want to see it patched, others might say, well, if the original coating failed, let's strip it ALL off and redo it all properly. If the seller just does the patches now...the buyer has to take it on faith.

As the builder is still in business, perhaps they can recommend a qualified surveyor, and give an opinion on what the situation really merits.

[Delfin]

Originally Posted by makobuilders

Hi Rod, I bought a 40 year old steel boat of 65ft. I would say that when you own your own steel boat, it will be wonderful because you are maintaining it properly.

However, when you are buying a used boat, one sitting neglected like you describe, then it is assumed that there will be corrosion problems that need to be corrected, either through local sandblasting or by cutting out and replacing plating. Do NOT add patches on top of corroded steel.

I had a couple of small sections that needed to be cut/replaced and the yard bill was $5k. That was years ago. But there was bigger work needed that I delayed, so the bill should easily have been $15k+. You need to assume something like this with your boat as you go into it.

BTW, 1/8" steel plating is very thin. It is acceptable, but very thin. There is basically no room for corrosion in such a size. And if you are planning remote bluewater cruises then I would look for at least 3/16" hull thickness in a 40ft boat.

Corten 1/8" is as strong as 3/16" A36 mild steel, and more rust resistant.

[GordMay]

Originally Posted by hellosailor

I can appreciate an owner NOT fixing corrosion. Consider, if the buyer has a survey that says "Shows signs of recent repairs, exact extent of problem cannot be determined". That's what you get if it has all been nicely refinished and done. But by leaving the rust visible, it can be surveyed, can be evaluated, and the buyer gets to see what the problem is, before the seller turns around and pays for the repair job. And, different buyers might want different repair jobs.

Coal tar epoxy?? Coal tar is one thing, epoxy is another. Sounds like mixing fresh sushi and lean hamburger: A perfectly good waste of two good materials combined that way...

Well said!