SeaCraft is one of the few builders that provided a hatch so you could remove the tank to inspect it without tearing up the deck! That was the first thing I did when I bought my boat in 1975, and it was a good thing! During manufacture, someone had evidently dropped a brass nut used on the gages and the tank was resting on top of it!
Needless to say, that creates a pretty good battery! Fortunately I caught it before galvanic action corroded thru the tank. Cleaned it up, painted tank with epoxy primer and original tank is still going strong! Pulled it again in 2006 when I repowered to replace all the hoses and it was still in great shape!
SeaCraft brochures also used to brag about not having foamed in tanks! They said it cost more, because then they had to ventilate the bilge, but they did it anyway because it made for longer lasting tanks!