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BongoCruiser
07-17-2001, 08:41 AM
My friend has a 22' steel launch on Lake Winola Pa that was built by his grandfather in 1913. This weekend we rolled it over and found severe rust over much of the bottom. Since the cost of new steel is out of his budget he is considering prolonging its life by sandblasting and then coating the underwater area with epoxy. I'm sure this unconventional approach will generate some email but we are interested in any cost effective alternative.

RGM
07-17-2001, 10:46 AM
Hey Bongo, without more info I'll go ahead and throw this out there. You probably don't want to go thru the trouble, mess and expense of sand blasting the old girl. Besides, when the blasting is done the bottom of your friend's boat will probably look like Swiss cheese. Not good. Maybe he should just do some judicious disk grinding/sanding. Knock all of the loose stuff off, trim the holes back to good material, don't necessarily go for bright metal. Cut out some patches of sheet metal (not too flimsy, aluminum works good) and rivet the patches to the bottom of the boat where need be. Bed the patches in 5200, clean off the excess. Paint the entire bottom of the boat with epoxy bottom paint to seal up the rust the best you can. If you can't find epoxy bottom paint readily, just use epoxy (perhaps multiple coats). Good luck.

Phil Young
07-17-2001, 08:01 PM
Aluminium on steel is generally thought not to be a good idea. Maybe less of a problem in fresh water than in salt. Your repair plan sounds very short term. The trouble is once steel strarts to rust it gets quite aggressive. It will expand, crack your epoxy and blow it off. Some sort of rubberry compound might be better. Any marine googe will probably cost more than steel. Maybe some bitumen based roofing repair? Personally I'd grind away all the rubbish, buy a small arc welder and have at it with bits and pieces of steel. I think the boat has a pretty limited future though, and I'd be worried about taking it further from shore than the weakest passenger could comfortably swim. You need to see to believe how much water even a small hole will let into a boat. You get a 2" or so hole, no bilge pump is going to keep up.

ken mcclure
07-17-2001, 11:43 PM
Or you could go get some good mahogany, roll the old girl over and use her as a plug for a great cold-molded boat!

Bruce Hooke
07-18-2001, 10:14 AM
Are you sure epoxy would be cheaper than steel? Steel is generally pretty cheap stuff if you can find a commercial supplier to buy it from. Of course if installing it is the problem then that's another story.


I have had good success patching up car bodies with fibreglass cloth and polyester resin, but then a small leak in a car is not that big a deal (at least if your car is old enough to need this sort of patching!). The usual technique is to grind off any paint in the area, put in something (thin sheet metal, an unrolled coffee can, whatever) to bridge the gap and then lay on a good coat of fibreglass cloth in poly resin. That should be a lot cheaper than epoxy and in this case I think it would work about as well. But, as others have said, I would be sort of careful where you take this boat if you have any doubts about the repair job...

[This message has been edited by Bruce Hooke (edited 07-18-2001).]

Wayne Jeffers
07-18-2001, 10:46 AM
Several years back, Boatbuilder magazine had an article on using "coal tar epoxy" for rustproofing steel hulls. I have no experience with steel or CTE.

You might run "coal tar epoxy" thru Yahoo or your favorite search engine and see what you can learn about that. Or maybe other Forum members know something about it.

Wayne

Bob Cleek
07-18-2001, 10:03 PM
Hey! Wait just a damn minute here... I don't think they were even building STEEL boats back in 1913, particularly 22' launches (whatever that means.) In 1913, there was very little STEEL boatbuilding that I've ever heard of. No welded steel for sure. Back then, I think all you were seeing was riveted iron plate, and that only on ships, not 22' launches, because of the weight factors. This sounds like a very unusual, and perhaps historically significant, vessel, if it really was built in 1913. It ought to be easy enough to identify. If it is riveted together, it's iron. If it is welded, it wasn't built probably before WWII. If it is riveted, check out your local maritime museum before you butcher what may be a valuable artifact. If it is welded, slap another plate on the bottom. Don't be penny wise and pound foolish. Steel plate and welding are very cheap. Check around. You'd be surprised. And... you end up with a perfectly sound bottom.

Dumah
02-24-2010, 06:29 PM
I don't know the availability in your area, but for my money I would check the local scrap metal yard for used plate from steel silos, etc. One can often acquire this material for slightly over scrap price and by careful buying, get "new" quality steel. Do NOT take a chance on a severely pitted hull, you and your loved ones are worth considerably more than the time and effort to put a vessel afloat without ensuring she is the best that she can be.

Cheers, Dumah,
Halifax, NS

NealmCarter
02-26-2010, 06:44 AM
I would be very careful when sand blasting rotted steel..the plating is probably so thin that you will cut large holes in it.

flyinwall
02-26-2010, 07:04 AM
i would be interested in seeing this boat to see if it a golden olden or something else
and some pics of the affected areas as well so you can get more detailed responces

skaraborgcraft
02-26-2010, 08:19 AM
steel is the cheaper option here. The problem may be to find sound steel to weld to. We took on a repair of a 26ft sailboat that had a "slightly rusty" shell plating underneath,but less than 2 minutes with a grit blaster proved the plating was in bad shape.We had the problem of having no sound steel to weld new plates to. The owner ,in a rush to head East (into the Med)decided to glass the bottom to maybe 5 inch above the waterline. We used polyester resin due to the fact it shrinks slightly on curing. She was still sailing 8 years later....and no leaks. Cheers

nedL
02-26-2010, 08:27 AM
Anyone notice that this is a nine year old thread? ;)

skaraborgcraft
02-26-2010, 08:30 AM
NO......lol.....but the answers are just as valid....

Tom Robb
02-26-2010, 12:57 PM
Is Bongo still around?
I wonder if Cleek was right and what Bongo did with the launch.
And how did this get back on the Forum anyway?