Fixing corrosion in aluminum holes

[Ride432]

From what I've seen this topic has been beat to death and in all my searches I couldn't find the answer I was looking for. I have a 93 Lund ws16. I traded for it not knowing much about boats and probably shouldn't have done it but I have it and am stuck with it for now. From what I can tell I don't have a big hole anywhere just a bunch of little holes although I couldn't pinpoint them when I filled it with water aside from leaking from the engine mount bolts which I've put 3m 4200 on and fixed. There are a lot of corrosion spots that may or may not be contributing to the water I'm taking on. I plan on sealing all the seams and rivets with gluvit and I'm wondering if that will work well on the corrosion spots? Or should I use 5200 on them inside and out or durafix brazing rods? It's too much to patch with riveted on patches and sealant like 5200.

And cheapest option for flotation foam replacement as mine is acting more like lead than something that floats

 

[Scott Danforth]

Iboats sells 2-part foam

As for the holes. Could be electrical bonding failure causing electrolysis, could be corrosion, could be a number of things. Got any pics?

I once went to help someone that had "a few small holes". Using a work light in the hull at night, it looked like the milky way. Must have been a few thousand pinholes. The owner had installed equipment and used the hull as a ground. Ended up scrapping the boat

 

[Renderwurx]

I have a similar issue... although they aren't all over... just in small patches so easy to see from the inside. None appear to be all the way through... most exhibit hallow pitting. I am pretty sure they are from POs using the hull as common ground. Most are in patch/line that follow each stringer up the length of the boat.

What I am trying to determine.. .is what if any steps I need to take other than cleaning the corrosion off I should take. Fill the holes with bondo? JB Weld? Gluevit?

Or just use aluminum cleaner, etch the metal and then primer?

Here is what the corrosion looked like before touching them:

Here are what they look like after wire brushing them:

A few seem deeper but it could just be how close I am and shadows:

 

[Renderwurx]

BTW... I did do the light in the boat check... I don;t see any light passing through the hull anywhere thank goodness. I just want to stop the corrosion that exists. And of course wire the boat RIGHT!

 

[djrowe007]

wow that is bad, we had a 2014 aluminum boat come in for repair that had that same kind of aluminum damage. His occurred much faster though obviously and he had huge 1/4" holes and cracks all over. It almost looked like it came from the areas that were welded together on the hull. The hull was replaced and the cause was unknown, not every customer tells you the full truth. I thought it might have been galvanic corrosion and it attacked all the joints on the boat, but I also thought it may have been an issue with the aluminum and welder settings used or bad metal.... If you ask me id have to grind those areas down before patching them, and you cant get to the inside so good luck. Hopefully you can find a temporary way to patch them from the outside. No idea how long that would last for, maybe for a while, maybe not I don't have enough experience.