The Ronco Plastics B504 is one of the flattest tanks in the marine B-series: 18 gallons in a low, broad molding that vanishes under a v-berth or cockpit sole. At 29 lb, it goes in with one set of hands and stays out of sight for good.
Its role is set at order time, because this is a dual-role molding. Fresh water fittings make it a potable tank in food-grade polyethylene; waste fittings make it a shallow gray or black holding tank. In a tank this flat every port competes for the same top surface, so Ronco's per-order fitting installation, spin-welded or threaded to your exact marks, is not a convenience but a requirement done right.
Full, it carries about 150 lb of water at 8.34 lb per gallon, spread wide and sitting low, as friendly to trim and stability as ballast gets. Print the dimensioned drawing below and finalize placement with the on-page fitting planner.
Molded in Tustin, California by Ronco Plastics, at the trade since 1974. Compare the 18 gallon holding tank for a dedicated waste role, or browse low-profile formats across the RV water tanks and marine collection. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B504 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.
