The B415 puts 28 gallons in a noticeably heavy shell - the bare blank weighs 91 lb, which tells you how much polyethylene Ronco puts into this particular mold. Wall mass is what you want in a tank that lives against a hull and takes pounding underway: the material absorbs flex instead of transmitting it to fitting joints.
It is a B-series dual-role molding, so the same shell serves as a fresh water tank or as a gray/black waste holding tank - the role is set entirely by which fittings you order and where. Nothing is pre-drilled. Print the drawing below, mark inlet, outlet, and vent where your plumbing actually runs, and Ronco spin-welds or thread-installs to those marks in Tustin, California, the way the company has fitted tanks since 1974. The on-page fitting planner helps you translate hose sizes into fitting picks.
Budget about 234 lb for the tank brimmed with water when you size the shelf or cradle under it. If this footprint is wrong for your bay, the boat tank category has the same capacity in other proportions, and the full catalog lives on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B415 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.
