The installation of my bilge pump float switch is somewhat unique in that it is on a removable bracket. It's a nice idea, but poorly executed. The bracket is aluminum and when I bought the boat, the float switch didn't work so I set about replacing it with a Rule Model 35A. The original was attached to the bracket via stainless steel hardware with no barrier between the two metals - a textbook recipe for galvanic corrosion.
I made a temporary fix by bolting the new switch base on with a nylon spacer, but knew it was only temporary. This winter I removed the bracket again and decided to do something more permanent and such that the switch will always be easy to clean or replace. Despite the fact that there was a spacer and only one fastener, the corrosion had progressed somewhat. Nevertheless, it was sound enough to be encapsulated. The first thing I did was to bore out the holes on the switch base from 6mm to 1/4" so as to accommodate 1/4-20 screws. This is best done by hand with a .25" twist drill. Secondly, I cut a piece of scrap fiberglass left over from my bilge pump control panel project. It was part of the starboard settee and about .25" thick. Fiberglass can be drilled and tapped, and given that the switch base will not be under any real shear or tensile loads, this will be more than adequate.
I glued the fiberglass piece to the top of the bracket using WEST thickened with 403 adhesive filler. Then I built a mould out of cardboard covered with packing tape and sealed with modeling clay. 1/4-20 screws coated with Vaseline (a very good release agent) kept the epoxy out while covered the bottom with about .200" of WEST thickened with a little bit of 403. I figure the threaded holes are now about .325" deep.
A good sanding made it presentable, but I will never win any awards for my prowess when it comes to this kind of stuff. The important part is that it works, and coupled with the dry bilge system should last a very long time. The last thing I did was add a wire tie mount about halfway up the bracket to neaten up the wiring.
I made a temporary fix by bolting the new switch base on with a nylon spacer, but knew it was only temporary. This winter I removed the bracket again and decided to do something more permanent and such that the switch will always be easy to clean or replace. Despite the fact that there was a spacer and only one fastener, the corrosion had progressed somewhat. Nevertheless, it was sound enough to be encapsulated. The first thing I did was to bore out the holes on the switch base from 6mm to 1/4" so as to accommodate 1/4-20 screws. This is best done by hand with a .25" twist drill. Secondly, I cut a piece of scrap fiberglass left over from my bilge pump control panel project. It was part of the starboard settee and about .25" thick. Fiberglass can be drilled and tapped, and given that the switch base will not be under any real shear or tensile loads, this will be more than adequate.
I glued the fiberglass piece to the top of the bracket using WEST thickened with 403 adhesive filler. Then I built a mould out of cardboard covered with packing tape and sealed with modeling clay. 1/4-20 screws coated with Vaseline (a very good release agent) kept the epoxy out while covered the bottom with about .200" of WEST thickened with a little bit of 403. I figure the threaded holes are now about .325" deep.
A good sanding made it presentable, but I will never win any awards for my prowess when it comes to this kind of stuff. The important part is that it works, and coupled with the dry bilge system should last a very long time. The last thing I did was add a wire tie mount about halfway up the bracket to neaten up the wiring.
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