3M has the 5200 silicone and the fast dry 4200 silicone. Has anyone used these products for sealing up holes? I have an aluminum boat and the product description doesn't mention aluminum surfaces but I don't see why it wouldn't work.

 

Any suggestions? It's anywhere from $17 to $26 a pop so I'd like to get the right one.

I've used both on my aluminum hull. I forget which is which but one of them is about permament so don't use it on something you may want to remove.

I used them on screws.

The permanent type was used when attaching this transom extension:

5200 will be fine.

I think the 4200 can dry in about an hour. It may be the permanent stuff.

5200 is permanent for what you want to do thats what I would use. Ive seen where it was used on a motor bracket and when they pulled the bracket off the gelcoat/glass came with it.

3M 5200 is great stuff, but, it's not silicone.  At least it's not the same type of silicone you'll find in hardware stores.  It's an adhesive, and a darn good one.  It cures very slowly, but, it will even cure underwater. 

 

If memory serves, it cures faster in a wet environment than in dry.

 

Yes, it will stick to aluminum.  It should work very well to seal leaks.  I recommend cleaning the area around the hole and hitting it with sandpaper to roughen the surface.  Force  the 5200 through the hole so that you have a good sized drop on the opposite side.  Leave the same size drop on the side where you applied the 5200.  Spread the drops onto the prepared surface, leaving it a little higher in the center.

 

Then let it sit until it firms up.  It could take a few days, but once it's set, your leaks should be permanently fixed.  5200, in addition to being a very strong adhesive is also very durable.  It can withstand a lot of abrasion from the elements.

 

It will also remain flexible, so if the aluminum around it flexes, it will flex with the aluminum and the bond will remain intact.

For leaks in aluminum Cabela's has a hot melt epoxy that works very well, you need a heat gun and sandpaper. When you know where the leaks are rough them up good and melt the epoxy onto the spot. By the time you clean up and put every thing away you're ready to try it.

Rodney

Good information guys. The spots I'll plug are the old transducer mount holes. Not a big deal but holes in boats don't go together! I'm pumped up to finally get a chance to mount my new graph and transducer. I feel like I'll finally be able to scan for structure now.