Repairing pinholes in hull

[zuren]

I have a 14' Mirro that has leaked badly since the day someone gave it to me (now I know why it was free). It was shoved off to the side for the past couple years but I had to move it so I looked at it closer tonight. I always though it was a leaking rivet or 2 for a floor rib, but I found a line of pinholes that are aligned with that interior reinforcing rib (so I never saw light shining through when I looked for pinholes before).

They are effectively blind holes that are only accessible from the exterior surface of the hull. I count at least 40 of them. I used a sharp pick and was able to enlarge some of the holes due to the aluminum being compromised.

What is odd is the holes only seem to be in that one defined strip. In any case, is there a point where "X" number of pinholes in a hull is too many to consider fixing? I can see other epoxy patches on the hull.

If this is fixable, what is the recommended approach? My use for the boat is rowing around my pond. It will never see a trailer, motor, or bigger water while I own it.

Thanks!

 

[DaleH]

Clean, sand area bright w/ metal paper ~80-100 grit, clean again w/ white vinegar & copper kitchen scrub brush/pad, rinse w/ water, let dry well, but prime/paint as soon as you can w/ aluminum metal spray primer. Few light coats better than 1 thick one.

Then apply West Systems G-Flex 650 flexible epoxy (kit is $22), lightly sand, then paint w/ gray Rust-Oleum paint (epoxy needs to be covered to protect against sun/UV damaged). Done!

 

[Weldorthemagnificent]

Dales is a good plan for a good looking repair. If all you want is a quick fix and don't care about how it looks, use JB Weld Steel Stik. I've had good luck with this stuff and keep some in my tackle box. It comes in a stick and you simply slice off a piece and knead it into a putty with your fingers. Once the color is uniform, press it into place and smooth it. It can be sanded later if desired but requires nothing else. Clean the aluminum beforehand like Dale said.

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[zuren]

Thanks...G/Flex ordered!

Is there a limit to the size of hole that the G/Flex will fill? A few of the holes are larger than "pin" holes. I was reading another thread here where a guy cuts patches from aluminum beverage cans to be used in combination with epoxy.

Thanks!

 

[Ronbedard57]

Hi,
If you've got an air compressor, get a cheapy air hammer and a riveting snout. Get some shorty rivets and washers and a helper. Drill out the holes to the rivet size, get your buddy to buck the inside with a ball-peed hammer head, and hammer them from the outside. Maybe experiment on a similar scrap first. Very permanent, and it'll match the other fasteners. Paint over them if you want to, but they're water tight if done right. There may be some other rivets that could use "bucking up" once you've got the equipment. (yes that's where the expression comes from)
Good luck
Ron

 

[DaleH]

Per the G-Flex 650 website, and somewhere on here I had posted as a PDF, they repaired a 3” hole in a canoe using an aluminum piece & G-Flex. Backed, this tin can piece on the inside, I’d say it would fix a 3/4” hole no problem.

Prep/clean/prime. Tape outside of hull with duck tape, position hole ‘level’ (can you take some doing, tilting/jigging up the hull), fill hole w/ G-Flex to level, add tin piece cover, let ‘kick’, i.e., tacky to touch, then lay down another coat over patch & 1/2” of surrounding area.

MUST be painted to protect against UV!

 

[SteveBob]

Another easy way is..... With the boat upside down, clean the areas as mentioned in the other posts. Wait for a sunny day. Cover the area to be repaired with an umbrella just to shade the area from direct sunlight. Then squeeze a little UV resin (the flexible type works best for this type of repair) over the hole, smooth out with a playing card or something similar, remove the umbrella, and let it sit for 5 minutes in direct sunlight. That's it.... You are done.

If you are having an overcast day and or the boat is inside you can use a UV flashlight to cure the resin in about 30 seconds. a complete kit with resin and UV flashlight is only around $20 on Amazon. The resin goes on and dries completely clear, is almost invisible, and will last for years. I use the hard UV resin when creating heads on jigs and flies that I tie and it works better than super glue on glass, plastics, or ceramics. This is the same stuff most auto glass companies use for chip repairs in windshields. But in your circumstance the flexible resin in my opinion will serve you better. Depending on the hole size a 10ml bottle should be plenty to do the job. If the holes are too large, you can do the edges first then cure it. Then slowly work your way towards the middle until the hole is completely covered. This will work great on any hole that's less than the size of a #2 pencil.

I use Solarez UV Dual Cure, Low-VOC Clear Polyester Resin. It's a little bit more expensive, but it is the most durable and is more consistent in quality than the generic or no name resins available.

As Uncle Red Green always says..... If women don't find you handsome, they should at least find you handy... So I learned to be handy at a young age LOL!!!!

Steve Bob

 

[zuren]

All of the holes on mine will be "blind holes", so I won't have access to both sides of the hull. They are directly under a rib, which I don't quite understand. I'm guessing something collected under that rib that helped the corrosion.

 

[SteveBob]

Probably something that was spilled over the area inside the boat where the leaks are and not properly cleaned up. Probably battery acid from your description of the holes. If it was battery acid it may have been soaked up by debris under the rib and thus allowed to eat away at the rivets or skin of the boat or both for an extended period of time causing the leaks.

 

[Weldorthemagnificent]

Good call on the battery acid theory. Maybe a baking soda slurry poured inside and let sit would neutralize any remaining acid. Couldn't hurt.

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[SteveBob]

The reason I know about battery acid is the boat I currently own has the same issue or should I say had?