These tanks have been driving me nuts.
I wanted 2 of them, and I wanted them under the splash pan so they would not interfere with my rear bench seat. So I cut out a plywood platform, glassed it, and fit it tightly under my lower transom crossmember. Then it kept coming out, so I tried to anchor it in the middle with an aluminum bracket, and ended up getting it to stay in place with another bracket on the port side. But the platform only worked if I could get the tanks on top of the crossmember, and that wasn't too much fun, so I installed a couple of ramps to slide them up in easily. That worked good, but they of course slipped out very easily.
So this a.m. I sat in the boat looking at these tanks trying to figure out how to hold them securely in place, yet be able to remove them easily for filling. As I looked at my Tempo tanks I realized there were round indentations on the bottom that a piece of 3/4" pvc fit perfectly in. With the ramps, I needed to fashion blocks that would support and hold the pvc pipe in place with 1/2" electrical conduit clamps on each end of the platform.
Got that done, and then took an old fender holder to hook a heavy duty bungee cord to that fits tightly across the top of the tanks to the center platform bracket (near the trim pump). The pvc pipe holds the tanks in place and the bungee cord holds the tanks down onto the pipe. Presto zippo! Sort of...
Now to get the bench seat done, and build a compartment under the dash in the center hull. Getting there!
Frank