I have aquired two large pontoons, 24' in length. Don't know if I have the Insert Image thing right, but here goes,
I was given these pontoons because they leak. They have some pinholes scattered along the water line, apparently caused by electrolisis. Perhaps it was copper antifouling paint on aluminum, or a faulty electrical connection but regardless of the cause the point of the post is how best to repair.
After getting many suggestions such as riveting a strip of aluminum embedded with 5200 caulk, to fiberglass and epoxy patches, the plan I'm most comfortable with is to remove the paint, clean/neutralize the aluminum and then completly cover the hull with fiberglass imbedded in Gluvit.
I know this may run in excess of $1,000 for materials but I believe the end result will be worth it. My main criteria is to have a repair that is thorough and done right the first time.
If the picture did not post perhaps the little one below is viewable. It shows how I have removed paint from the front of one of the pontoons. I don't want to start a discussion on the cause of the holes but am only looking for advice on doing this repair in the manner that will give me the greatest peace of mind.
cold tar epoxy thinned with zylene painted on is supposed to make the pontoons like new. The only question in my mind is about how electrolysis (white powder) tends to show up not too long after application.
Can anyone answer this part? I don't know how or if electrolisis can be stopped.
I read up on Coal Tar epoxy and found it has quite a few drawbacks, the main being an oily residue that makes it hard to topcoat.
I've also found some more threads on gluvit with fiberglass and think that may not be the best choice either.
How about laying down a band of 3M 5200 along the waterline/problem area, coving it with fiberglass tape and then a second layer of 5200. All the boat folks I spoke to swear that 5200 stuff will be there forever. One guy said make sure you never want to remove it cause it will be on for keeps.
It's your $$$$ and your choice to do what you'd like, but you're thinking of putting upwards of a thousand or more dollars into this. If what you're dealing with is electrolysis the areas even without pinholes are probably also paper thin. Is it really worth the time, effort, and money to make what would probably be a compromised repair with little life expectancy.
But I do understand you being eager and like to put a boat together also. But why not attempt to start out with some pontoons in good enough shape to justify the project.
New Scratch & Dent Pontoon Tubes
New Pair of 25' X 25" Pontoon Boat Tubes $1695.00
New Pair of 18' X 23" Pontoon Boat Tubes $1495.00
New Pair of 22' X 25" Pontoon Boat Tubes $1595.00
See they are available out there, a bit more than the possible thousand dollar plus repair though. But when you've put the time and effort to assemble the entire boat you'll actually have something that will last a long, long time.
I have considered using the money from scrap toward new pontoons or toward an entire boat and if thats the best way to go I'm all for saving the work, but these pontooms are really solid even at the pitted waterline. Also they are quite large compared to the average pontoon, They are square topped, not round giving them more bouancy something I like since I may start with a deckboat but turn it into a houseboat.
Please forward me the link to those prices, they are better than what I expected. The marine shop I got these from said they would cost about 10 K new. If I can really buy something comperable for under $2000 its a no brainer to scrap these.
In the photo of the stern you can see 2 holes drilled top and bottom I suppose to drain them. They have a drain plug but maybe someone thought this was faster. I stuck a probe 4 ft into a hole and did not hit anything like foam.
I did the hammer test and the hammer bounces just fine. Also, just banging and pushing all over the pontoons they have a very solid feel. I'm thinking they are about .09 thick.
I called the fine folks at 3M to talk about 5200. They said I could apply it directly to the abraided aluminum. I thought I may have to go to a 2 part epoxy aluminum hull primer.
I'm starting to form a plan, apply a band of 5200 along the pitted waterline and embed a strip of fiberglass in the caulk, completely saturating the cloth with 5200 (allowing considerable time for full cure). Also, a coat of the 2 part epoxy aluminum primer either before or after the 5200 patch. Then topcoat with a good paint.
Thats my best idea so far and I'm still open to suggestions.
Ran into almost the same issue with a "tinny" (aluminum) fishing boat belonging to a friend two years ago. (Had pin holes all along the water line.) While not exactly the same as a toon I think the repair process would work fine. We used a product called "Lab Metal" made by Alvin Products.
Like ANYTHING using aluminum, prep is everything and the surfaces must be shiny clean and roughed up a bit with sandpaper (or steel wool) to give the product some bite. You want to apply the product IMMEDIATELY once the aluminum is cleaned/sanded because it oxidizes almost instantly. One advantage we had was we could coat both sides of the aluminum. If you can access the inside of the toons I would do it the same way. As a side benefit, Lab Metal can be machined, sanded and coated with just about anything once it has set and hardened.
All in all, it was a cheap fix that seems to be holding just fine after two years use.
When I called the fine folks at 3M about using their 5200 stuff with fiberglass tape, the nice lady gave me this advice, "when in doubt, try a test piece"
Here are the results of my test.
The first photo shows two kinds of fabric. The roll is something called Poly Mesh Fabric distributed by Geocel and is used along with their 2315 sealant. That product is advertised to completely and permanently seal roof leaks. The other sample is a piece of fiberglass cloth, maybe 4oz or 6 oz I'm not sure.
The second photo shows both fabrics imbedded with 3M 5200 stuff on a piece of bare aluminum sheet metal.
The third photo is a close up of the Poly Mesh fabric saturated with 5200.
I like the way the Poly mesh fabric took to the 5200 making a nice smooth thin patch. The thing is I don't know if I can use this stuff for this application.(underwater) I assume that it is basically a Polyester fabric. It is probably half or a third as thick as the fiberglass and if you stretch it out of shape you can pull it back into shape without damging or pulling it apart.
I am comfortable enough with the results to feel I want to use 5200 along the pitting at the waterline in a 4' wide band, but my question, What type of cloth tape should I use?
If I would be better off using fiberglass, is there a thin weave that would give me good results?
have you flipped them over?are the open on top? if they are not i would think about opening them up with a large hole saw from the flat top part and inspecting them if you have access to a welder you can weld covers on top to close them up or srew a plate with sealant over them.
This is probably not what you had in mind but 2 years ago I fixed a dime size hole in the bottom of an aluminum lake boat I had with JB Weld. 2 years later the guy I sold it to is still using it with no problems.
WARNING: In the event of the Rapture My boat will be UN-Manned!