As I mentioned earlier, all waste water plumbing will be schedule 40 PVC and all fresh water will be PEX. PEX is chosen for its flexibility and durability and the PVS is chosen for its durability and price. I think PVC is generally not used in pleasure boats because it comes in stiff straight runs and not well suited for the curved surfaces of a boat. It also requires glueing together (actually chemically welding) and can be a bit of a pain to cut correctly. Or at least I thing these are the reasons builders don't use it on pleasure boats. It is much much cheaper than sanitary hose, lighter and I suspect PVC is more impervious to odor than conventional sanitary hose. I've worked with PVC quite a bit on residential projects. I've also learned that it can be bent to pretty tight curves given a bit of finesse. The trick is heating the pipe to the right temperature and not trying to bend it too much in a single heating cycle. I found this out when I built a steam chamber out of 4" PVC pipe back when I built my first canoe. The steam chamber worked great but it started to sag in the middle. I thought at the time that knowledge would come in handy. Sure enough, I was able to bend 1.5" PVC to the curvature of the side of the hull (see pictures below). Cuts still take some trial and error in the tight spaces of the hull of a boat. Dry fit the pieces together and don't glue up too much at one time. Remember that when you add glue to the joints being joined, they slip a bit tighter that they do when you are dry fitting them. As for transitioning to marine fittings, such as pumps and through-hulls, a 1.5 - 1.25 rubber transition bought at your local hardware store works perfectly. These rubber transitions are tough and made to last forever. They also add some vibration isolation and flexibility when attached to pumps and rigid fittings. All tank fittings are designed to work with threaded PVC fittings or glue in PVC fittings son no weird transitions needed.
Dec 4,
It's almost time to say good-by to the holding tanks. Soon they will be covered by the sole. I still need to add a vent to each tank. I have the fitting but have not decided the best way to proceed.
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| Working through the rough plumbing. The pump-out is a 1.5" PVC schedule 40 pipe starting at the bottom of the tank connector and drawing straight up and around the starboard tank. It then encounters a "Y" where the straight part continues to the pump-out port on deck and the branching part goes to the waste pump and up through a vented loop and back down to a through hull fitting. The vented loop portion and through hull fitting are not shown. |
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| Cut our some flooring that will go under the cabinets in the galley. You can see the "U" galley if you ignore the 12"x24" temporary piece that is in place in the middle so I can stand and pretend to cook. Plumbing access holes are not yet cut out of the sole. |
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| Preparing for laying down the fresh water tanks. These are aluminum "U" panels that wrap around the floor boards with 30# asphalt impregnated felt in between. The tanks will lay on these. No condensation issues here. |
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| Tanks in! |
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| I don't need any super expensive sanitation hose. Schedule 40 PVC is superior and cheap. Oh, and you can bend it after heating with a heat gun. |
Yes, the heat gun worked very well for the above bend. The technique that I used for this bend is that I held the heat gun so that it blew hot air into one end of the pipe. This heated the pipe evenly around the circumference of the pipe but tended to over heat the pipe on one end as apposed to the other. For short lengths this is not a problem. For intermediate lengths, you might want to heat both ends, one after the other. The pipe cools very slowly once heated so cooling is not a problem. For this bend, heating more on one side than the other actually worked in my favor. For long runs and gentle curves, I'll try heating the pipe externally and slowly working the bend I need into the pipe.
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| The tube to the deck goes to the deck pump-out. The "Y" goes to the over-board pump-out (pump shown) via a ball valve so I can replace that pump without stinking up the entire cabin. There will be a loop up under the deck before the plumbing goes back down below the waterline to a through-hull. I need to get the ceiling in first because all of this will mount to the ceiling under the settee. |
