I am replacing all the hoses on board—fuel, water, propane, and exhaust. Should I use rigid PVC pipe with short hose connections to give flexibility at the joints, or should the entire boat be done in the appropriate hoses?
Tom Wood responds:
There are few places on a boat where PVC is appropriate—notably for potable water, possibly for some seawater connections, but never, ever for such things as LPG (propane), fuel, or engine exhaust.
PVC is a semi-rigid thermoplastic, which means that it softens with heat, so certainly it would not make a good choice wherever high temperatures are involved. Being a petroleum-based product, it is not good at long-term immersion in oil-based products such as diesel fuel or LPG. But its main drawback on a boat is that it is subject to fatigue due to vibration, especially at any joints.
Even if it were an ideal product for use on board, the long, semi-flexible pieces of pipe are hard to work into the confines of a boat. Passing hose under bunks, through misaligned holes in the bulkheads, and around tight bends is enough of a chore using flexible hose. With PVC, it would be a major nightmare involving lots of short pieces with numerous hose joints, each one presenting a potential future leak.
I think I would stick with the proper hose for each application. And considering the work involved, I would buy the best quality hose, always matched to the fluid it will carry—it's a little more expensive, but always lasts a good deal longer.
Check out the Marine Hose Buying Guide in the SailNet Store, which will give you all the information you need to select the appropriate marine-grade hoses for the different systems as well as useful tips and installation directions. Good luck to you.