Replacement for Silicon

[tucker99]

Gents,
I have installed a bilge pump directly center aft at the bottom to transom seam. I installed it with silicon and it has stayed in place for a couple months. I've read here that silicon will corrode aluminum. Is there a good alternative? No I did not prime the surface. In fact, I got it down to smooth shiny aluminum. Is this an old wives tale and if not what is a good alternative?

 

[Wallyc]

I’ve heard the same so I’ve always sided with caution.
The big box hardware stores carry 4200 and 5200 silicone meant for marine use believe it’s made by 3m. If I were you and no sure what kind of silicone it is . I would strip it and start from scratch. Better safe than sorry.

 

[tucker99]

Maybe you're right. But, I'm checking and don't see any other reference to it being corrosive except on this forum.

 

[57sailplane]

Marine Goop.. it even comes in a tube for caulking

 

[lckstckn2smknbrls]

Their is a brand called 3 in 1 sealer or caulk.
It has been said here on Tinboats that this product is safe to use on aluminum.
I have no first hand knowledge.

 

[wmk0002]

I recently saw a guy on Youtube who took a piece of sheet metal and bent it into a 90. He then riveted the bilge to this homemade bracket and then riveted the vertical leg of the bracket to a transom brace or something. I think he added something thin to act as a small shim between the hull bottom and the bracket to keep it from vibrating.

 

[tucker99]

To finish this up, I researched this because I wasn't looking forward to digging out all the silicone I used. Seems the corrosion thing was the case a long time ago. Newer silicone doesn't use an acid cure. I found this quote from a Temco rep:

"...that's a myth to a certain degree - what they are referring to is "acid cure" silicone - old 50-60 technology - the neutral cure silicones do not react with aluminum. Consider every high rise aluminum frame/glass building in the world is sealed with neutral cure silicone for the last 30 years."