Nauticat 38: Dual Fuel Supply and Return Explained

Both 300-litre tanks on our Nauticat 38 used to feed the engine through one filtration system. We wanted redundancy — so we split them. Solo sailor Steven Bates walks through the new setup: each tank now has its own pre-filter and fine filter. A six-port valve switches supply and return together, so unused fuel always goes back to the same tank that is feeding the engine. With the engine running you can move the lever from port to starboard with no misfire and no delay. What we cover: • Why one shared filter was the weak point • Port tank → pre-filter → fine filter → valve → engine • Matching starboard system • How the six-port valve switches supply and return together • Live switchover with the engine running Six-port valve used: https://www.maestrini.it/en/product/6-way-ball-valve-l-type/ More on Maja’s engine and systems: https://sailing-maja.com/engine-systems-electrical/ I’m 53, a mechanical engineer, and documenting the practical side of leaving the hamster wheel on our Nauticat 38, Maja. If you want honest systems work and real boat solutions, subscribe for the next video. Chapters: 00:00 Intro of the old problem with two fuel tanks and one fuel 00:20 The solution, a six port fuel valve 00:30 Port tank and filters 01:03 Six-port fuel valve 01:34 Return to the same tank 01:58 Starboard fuel system 02:37 Two completely separate fuel supplies giving complete redundancy 02:58 Switching tanks with the engine running 03:31 Why this redundancy matters 03:49 Checking the system for leaks 04:39 Operation 05:06 Outro