Thetford - Porta Potti - 135 Marine Toilet with Hold Down Kit - 92861. Whether you're a day tripper or a week-long cruiser, our marine portables are compact, convenient and designed with marine-specific features and benefits. Thetford Marine Porta Potti - don't leave the dock without it.. Design. Modern appearance. Ergonomic Carrying Handle. Standard Lid Latch. Durable, easy to use and easy to clean. Removable seat and cover for easy cleaning. Functionality. Exclusive, rotating Pour-Out Spout. Bellows pump flush. Sealed valve keeps odors in holding tank. Deodorant sample included. 3-year warranty. Owner's Manual (pdf)