Five inches. That is all the height the Ronco Plastics B288 asks for, spreading 9 gallons across a 32" x 15" pancake that slips beneath floors, berths and cockpit soles where nothing else goes. Underfloor tanks like this are how small boats and vans find capacity without giving up a single locker; the payload rides at the lowest point of the vehicle, which is also the best place for it. The molding weighs 17 lb and holds about 75 lb of water when full.
Order it fresh or order it foul: the B288 is a dual-purpose marine and RV molding, and the fittings determine the job. With potable fittings, the FDA-grade polyethylene serves drinking water duty; with waste fittings, it becomes a slim gray or black holding tank. On a tank this flat, port placement is the entire installation - a mislocated outlet strands a gallon you cannot pump - so print the drawing below, mark your low point and vent, and verify the layout with the on-page fitting planner. Ronco spin-welds or threads every fitting exactly where you say.
The B288 comes out of Tustin, California, where Ronco Plastics has molded marine and RV tanks since 1974. Underfloor formats run all through our boat tanks and RV holding tanks collections if you need the same idea in a different rectangle. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B288 dimensional drawing - print it to plan your install and mark exactly where you want fittings located; Ronco installs spin-weld or threaded fittings to your marked spec.
