Look at the ratio on the B420 before anything else: 27 gallons of capacity carried in an 89 lb molding. That is a lot of polyethylene per gallon, and it is the point - this is the workboat-grade end of Ronco's dual-role marine series, a thick, dense shell for installations that get vibration, pounding, and indifferent maintenance. Ordered fresh it is FDA-compliant potable material; ordered as a holding tank the same shell runs gray or black waste.
Full of water it totals about 225 lb of contents on top of that heavy wall, so give it the same framed support you would give a much larger tank. The mass that makes it durable also makes it a two-person lift even empty - plan the install path through the boat accordingly.
As with every Ronco tank since 1974, fittings are installed per order at the Tustin, California plant, spin-welded or threaded exactly where you mark them. Print the drawing below, mark your penetrations, and enter them in the on-page fitting planner. If you need capacity without the armor, the 25-gallon RV49W is the light-duty comparison point.
Full marine listing under boat tanks; everything from this maker on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
