Epoxie On My Steel Yawl Bottom

[roaminraulf]

Hi
I have electrolis`s damage below the water line, on my 41ft steel yawl, when I hauled out to clean the bottom I had 1/2" holes in solid steel plate, (a mystrery how it stayed afloat) I will haul my boat to my yard ,sandblast it , and cut out and replace any plates as is nesessary, but I am thinking it might be like a sieve when I do blast it, and be too much damage to " replate" without doing the whole bottom below water line, that is not feasable at this time,
My question is , will it be o.k. to coat with multiple coats of epoxie, thin at first and thickened as I get into the last coat/coat`s, ? I have no experience at doing this, and I am getting lots of different opinions on it , also what epoxie should I use? and should I use fiberglass cloth? or?? just go with epoxie fairing? I will be glad to get some in-put by experienced sailors and boaters, as I know I will here on cruisers forum,
Ed Gushue Yawl Estrellita iv
charleston s.c.
P.S I have already plug-welded the holes,

[Rustic Charm]

Originally Posted by roaminraulf

Hi
I have electrolis`s damage below the water line, on my 41ft steel yawl, when I hauled out to clean the bottom I had 1/2" holes in solid steel plate, (a mystrery how it stayed afloat) I will haul my boat to my yard ,sandblast it , and cut out and replace any plates as is nesessary, but I am thinking it might be like a sieve when I do blast it, and be too much damage to " replate" without doing the whole bottom below water line, that is not feasable at this time,
My question is , will it be o.k. to coat with multiple coats of epoxie, thin at first and thickened as I get into the last coat/coat`s, ? I have no experience at doing this, and I am getting lots of different opinions on it , also what epoxie should I use? and should I use fiberglass cloth? or?? just go with epoxie fairing? I will be glad to get some in-put by experienced sailors and boaters, as I know I will here on cruisers forum,
Ed Gushue Yawl Estrellita iv
charleston s.c.
P.S I have already plug-welded the holes,

to hear that. I'd suggest cutting out and fixing properly. Fiberglassing over metal doesn't seem to work very well. But that's just one experience of it.

[delmarrey]

Epoxy will stick to steel with a sandblasted surface. But once it starts to rust it will delaminate. And doing patch work would shorten the time factor. The edges would go first and start the creeping process.

I think I'd spend the time and effort to re-plate the whole bottom, if that's what it takes. Fiberglass and resin is not cheap either.

Also the expansion and contraction of steel compared to epoxy, I'm sure would be a problem. You would want to put on epoxy when it's hot and dry. It doesn't adhere to moist surfaces. Then when you splash the steel it would shrink. Lots of things to consider, like twist and flexing too?

Make up some samples and put them through some tests. Bondo has worked on cars for years but they are not submerged.

[boden36]

If you want a medium term but messy fix, you can just plate over the thin areas, without removing the original plate. If there are holes in the original plate, weld them to the doubler from the inside if possible to seal the plate.

Regards,
Richard.

[Old Snipe]

Hi roaminraulf,

Like boden36 said, Plate over it. Weld the outline of the patch and then corroded area from inside the hull after grinding away enough metal to obtain a suitable thickness for welding. I used to run across this all the time on old steel hull MK6 boats in the navy. They had so many patches underneath that they looked like a bad checker board. We were constantly chasing thin hull leaks on some of the older craft. Every time we got a boat up on skids, we would walk around with pick hammers and sound the hull. We almost always found a few more.

Glass and resin should only be used for a emergency situation to buy a little time with a steel hulls.

[HopCar]

Before the Coast Guard ran them out, there were a lot of rusty steel freighters on the Miami River. They would buy Z-Spar Splash Zone Epoxy Putty by the case to keep those things afloat. That's a very temporary fix. The other guys are right, replace the plating.

[shorebird]

Test the steel thickness over the entire hull below the waterline before deciding on any action. Know thy enemy.

[hpeer]

My experience is that the damage MAY be very localized .

Don't panic just yet.

I don't hold any credence in those ultrasonic testers. Not that they are bad, just that the rust can be so localized that it is easy to miss.

Blast and tap is better.

Sorry to hear of your problems.

I blasted last year and put on a new bottom coat. If you have the time, energy, and are short on money I would consider stripping the bottom with a flap wheel. It's cheaper than blasting and you can then recoat smaller areas as you expose it.

Also, you can get a welder and learn how to weld yourself. It's not terribly hard, you will learn a lot, and it's cheaper. Again it's a balance of time, energy, and money.

Just a thought.

[Compass790]

I had a steel plate keel with a lead bulb on the bottom that was very rusty. Ground it, welded where necessary & used a cup wire brush on a 9" grinder as couldnt sand blast it in the slipway. Treated with rust kill ( Phosphoric acid), Painted with coal tar epoxy, maybe 2or 3 coats & then about 7 coats of Ameron epoxy. No rust after 16 years except the keels leading edge & bottom where it hit things.
Hope that helps regards Paul

[delmarrey]

Originally Posted by Compass790

I had a steel plate keel with a lead bulb on the bottom that was very rusty. Ground it, welded where necessary & used a cup wire brush on a 9" grinder as couldnt sand blast it in the slipway. Treated with rust kill ( Phosphoric acid), Painted with coal tar epoxy, maybe 2or 3 coats & then about 7 coats of Ameron epoxy. No rust after 16 years except the keels leading edge & bottom where it hit things.
Hope that helps regards Paul

Welcome aboard Paul!

[Compass790]

Thanks for the welcome. Wish I'd discovered this site earlier, a treasure trove of info that I hope to be able to contribute more to. Already I have received assistance from a member ( Wetdog) in supplying used parts for our Yanmar YSM 8 which are a horrendous price here in New Zealand.
Regards Paul

[h the boat]

Hi Roaminraulf, Repairing the bad bits is only half the problem, although other members have given good advice. WHY did your boat suffer so badly from localised Electrolysis ????. If you dont find out, in only a short time you may be back to square one... There are a lot of posts on this problem, take the time to go through all of them. You will then have the knowledge to make an intelligent summery of the probable causes and eliminate them. The time taken to research within the posts, will probably be longer than you will need to cure the originating problem... H the Boat.

[roaminraulf]

Thank You, that is good advice, I will invest the time and read those posts, as yet I still don`t know what caused the problem,

[roaminraulf]

Originally Posted by delmarrey

Welcome aboard Paul!

Thanks Paul, sixten years you say, Hmmm . let`s see, I am 76 now if I could get it to last that long I would be happy to "redo" it again sixteen years time, "Long may your big jib draw"
Ed Gushue sailing yawl Estrellita Iv

[Compass790]

Hang in there Roamin Ralf, my Dad is 86 & he still races with us. Good advice to sort your electrolysis issues out first. Also forgot to say the cup wire brushes with the spiral wound wire are really vicious at removing the rust. If you dont mind using a grinder without the guard you can get the non-cup (like a grinding disc layout) wire brushes with the spiral wound wires that also rip off the rust. I use them to clean out slag when pipe-welding, they stick a few wirers into yr flesh but boat maintenance is painful anyway. Better to wear overalls than shorts I tell ya! Also the flap wheel with coarse grit probably better to finish as wire brushes tend to polish but we didnt do it. I think the coal tar epoxy paint & getting lotsa coats on so you have good thickness is the most important. Used to do maintenace on fishing trawlers & they put me onto coal tar epoxy paint for steel hulls but they were pretty careful to keep their anodes in good nick
cheers Paul