Ninety gallons in a 39.25 x 39.25 inch square, 14.25 inches deep: the BOAT64W is the second-largest tank in Ronco's heavy-duty marine series and the largest square one. A symmetric footprint this size is usually a keel-centered installation - under a saloon sole or a berth platform - where the balanced shape keeps a very large water mass from ever loading the boat off-center.
It is molded with the H.D. marine wall in FDA-compliant polyethylene rated for potable water, at the Tustin, California plant Ronco has run since 1974. Fittings are installed per order, spin-welded or thread-mounted exactly where you mark them. Print the drawing below and take time with the on-page fitting planner: at this scale you are likely placing a fill, a vent, a pickup, and a sender, and the square deck gives you freedom to put each where the plumbing wants it.
Ninety gallons is about 751 lb of water. That is a structural project - continuous framed bearing, through-bolted restraint - and worth a naval-architecture minute before you commit. Compare the long-format alternative at the top of the range in boat tanks, price delivery on the freight cost estimator, or browse the family at the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.