Grounding Plate Issue

[markpj23]

Thanks guys - I appreciate the replies.

[S/V Illusion]

Thinking you can mechanically or physically preclude any voids and thereby eliminate any possibility of water penetration is counter-intuitive in that if in-tact glass hulls can blister by simple adsorption, so too any any glass in which a hole is drilled regardless of how careful you are.

Assuming the hull is solid glass, I would think it a far better and safer method would be to remove the whole thing, properly patch old holes and epoxy line any new mounting holes. That presumes you even want to use a dynaplate which, as the previous discussion indicates, makes an relatively ineffective counterpoise and a potentially problemmatic and poor DC ground.

[markpj23]

I removed the nuts from the studs inside the hull, moved the copper strapping out of the way and realized that there was not much separating the water from the inside...

There was, however, a neat trick used when these were originally mounted. A nylon or marelon bushing fit over the bolts on the inside of the hull. They applied a sealant underneath this bushing and then tightened the nut. When I pulled this off, I had a gasket formed of 4200 underneath this bushing. There is a trademark name "Wonderseal" on these and I guess they're made specifically for this purpose. I show two of them, the one on the right is inverted to show the groove where the sealant forms its own o-ring around the bolt.


After pulling these off, I was able to tap the bolts out / down with a hammer. Came out extremely easy.


So all that remained between the ocean and the people tank was the bushing and a caulking seal.... how comforting!