Even more interesting.
Deck plate seals are critical, at least for the top of the tank to keep it dry.
The (minor) damage I've seen on my 16 yr old tanks was galvanic damage, the pits, not the white stuff, and only under strips, a few, mostly on the tank bottom. I cleaned the areas and applied a full bed of lifeseal to the neoprene to the tank where it was to begin with, before putting the tanks back in boat. Now the neoprene joint is waterproof. I didn't have any pits at the wedge neoprene. Some pits on top cross member neoprene. And Grady used steel rusty staples on the top neoprene that left rust staines on the tank, talk about galnavic opportunity, but no, perhaps because it was dry.
And pits were more on rear aux tank than main.
All the tanks had was a thin coat of grey primer that came off in spots readily when I cleaned the surface, they were very dirty.
Grady just layed the strips on the subfloor and dropped the tank in place. I also had some pits under the sender neoprene gaskets, when the new corprene gaskets went in, I fully bedded the new gasket to the tank and sender flange.
Waterproof = galvanic damage-proof IMHO.
The white stuff is self protecting, I had little, and meaningless to metal thickness lost. The white stuff looks a lot worse than it really is.
The pits are like driiling small holes. No dust present, the metal was removed to something else. They can be a lot worse than they look.
Once salt deposits dry, they generally don't rinse off fully just from the flow of water especially from the distant plate locations, and worse trying to clear the bottom. Better off filling the entire bilge with 9 inches of fresh water, then letting it drain. Do it a few times. Don't do this on blocks or trailer.
Galvanic damage is from dissimilar metals (conductive) in a conductive solution, the claim has been the neoprene is creating the dissimilar condition, not from absorption. I believe it. I seen it.
I think I'd rather have the tank top dry of anything wet ever, saltwater or not. When it does get wet, unless the floor is taken up, don't see how it can dry in there fully, the tank compartment is purposely non-ventilated by design. I guess it could be power ventilated with dry air.
Since the bottom of the tank is very low in the boat, it is easy enough for a bilge water rise and the tank stern end first to become awash or splashed with bilge water while underway. Bilge water is going to have salt in it, for SW boat users.
Interesting.
One of those saltaway products may be more successfull in getting rid of salt deposits for those concerned.
