30-Year-Old Boat Plumbing Replacement

Replacing the 30-year-old copper plumbing in our fresh water system was on my Things-to-do-when-there-is nothing-else-and-I-have-lots-of-time list and I expected to get to it some time in the years to come. But as with all things boats, that was not to be. Our hot water began flowing ever so slowly out of all of the taps for no apparent reason. I disconnected some of the lines and attached a hose from the dock in an attempt to blow it out. I also took all of the faucets apart in case the blockage was there, but ALL of them? None of this helped so now the project shoots right to the top of my Need-to-do-it-now list.

The original plumbing had many different connections and was probably put in the boat as it was being built. Our problem was due to a build up of material in the copper pipe that by now had choked off the water flow almost completely. Taking it apart piece by piece to clear the obstructions was an option, but not one I would consider. Some of the runs passed through places that would be totally inaccessible without pulling the boat apart. Replacement was now our best choice, and I had to decide what type of material the new pipes and connections would be. A lot of study and research was needed to be sure we chose the right material, did it right and did it right the first time. The last thing we wanted was plumbing failures once we started cruising. I had considered replacing everything with PVC since the copper was not only too expensive, but too difficult to get into the needed sections of the boat to connect to the hot and cold water sides, make connections at the galley sink, and to the two head sinks, including the shower. The PVC was quickly ruled out because of the concern for failure of the glued joints as a result of vibration. After much thought and feedback, I decided to use the PEX system with the 1/2-inch pipe and plastic push connections. I was concerned with this type of plumbing for a boat, but having worked for a service tech for a large power and sailboat dealer in Texas, I knew many of the new boats were coming from the factory with PEX and had not had any problems or failures. Additional feedback from other boat owners that also had PEX on board convinced me that this was indeed the way to go.

My first task was to layout the pipes and connections on paper so that I would have an idea of how much pipe I would need and how many of what connections it would take to replace the old system. Since some of the piping had to be routed differently, I couldn't just count what was there now. Adding to the problem was the section where flexible hose had been added by simply sliding it over the copper tubing and hose clamping it to fit in place. We have had these connections come loose and fill the bilge with fresh water.

There are a couple of options with the PEX tubing. You can use the blue for cold water and the red for hot water or opt to use white throughout. For simplicity and to save some on the expense, we decided to use the white throughout, since the plumbing on Beach House is not that complicated. I also decided to purchase the 100-foot roll instead of individual 10-foot pieces. Had we needed mostly straight runs, I probably would have used the 10-foot lengths.

The fittings are fairly expensive, but I did buy several more than I needed. This saved running back and forth if changes were needed as the installation progressed. I also bought a cutting tool for the pipe. It's important to cut the tubing square to insert it into the fitting. Some new faucets were planned for the galley and head sinks.

Each fitting comes with a small insert to stiffen the end of the tubing as it goes into the fitting. These fittings are important to keep all connections together and leak free. The tube is cut square then the fitting inserted before pressing the tubing into the fitting. Be sure and keep track of the inserts since it is easy to forget one. That means taking the fitting apart, something I had to do a couple of times.

The tubing will fit into the connectors at about an inch and a quarter, so when measuring, an additional 2 1/2 inches need to be added. It took a few runs before finally getting the hang of measuring for the length of the tubing plus the connectors, but it quickly becomes easy and the tubing is forgiving if the measurements are not exact.

The handy cutting tool makes all of this a quick project. If you have the luxury of being able to shut down your system and pull out all of the old plumbing, then by all means do it. Since we live aboard full-time, doing without fresh water even for a day or so is a real inconvenience. The answer is to build the new system right alongside the old one. I did the hot water first, and when everything was in place, simply disconnected the old plumbing and reconnected the new. Then I could take my time removing the old copper pipe, which was no fun due to the pipe running through bulkheads and into places I have never accessed.

I chose the twist and lock push fitting for a couple of reasons. They were much less expensive than the SharkBite fittings and much easier to install than the crimp fittings, which require some very expensive tools to install. Putting the connections on is very easy to do if you follow directions. The fittings are threaded and have a blue line which tells you that the fitting is unlocked and the pipe can be inserted. If the blue line is not visible, the pipe won't seat, but by loosening the twist cap, the blue line becomes visible. With the insert in the tubing, push the pipe into the connector until it is as far as it will go, about an inch and a quarter. With the tubing fully inserted, the screw cap is tightened until it touches the body of the connector. The blue line will no longer be visible. That's it and the connection is tight and won't leak. The fitting can also be turned to any direction needed without concerns of breaking the seal.

The tubing will make some sweeping radius turns, but for the most part, will need 90-degree elbows, T-fittings and special connections for the sink faucets, hot water heater and fresh water pump. The tubing is rated for hot water according to the pressure on the system. We found it more than adequate for the boats hot water and pressure pump. The hot water in our system almost never exceeds 180 degrees, well within the rating for the PEX. Once all of the hot water side was finished, the change-over took less than 30 minutes to switch for the hot water heater, galley sink, both head sinks and the shower in the forward head. The old plumbing was disconnected and the new PEX reconnected at the same time.

With the hot water side done, the old copper plumbing was removed over the next two days. Then the cold water side was started. The hot water heater needed 1/2 inch NPT to twist-lock connectors and a few elbows to make the connections from the cold water inlet to the hot water outlet. The cold water side was much more involved than the hot water side. This would take a couple of days, but again, it was built alongside the old plumbing so we had no interruption to our fresh water on the boat.

The same types of connectors that are on the water heater are needed to bring water to the three faucets on the boat. I decided to add valves so the water could be cut off if the faucet needs repair without shutting down the entire system. This is much the same as found in most homes. The valves are then connected to the faucet itself by a flexible hose designed for just this purpose. Two of these are installed in each head and the galley.

The final connection is to the fresh water pump. A special swivel fitting connects to the pump itself. We also have a charcoal filter on our water system that has to be connected. It all went much easier than expected and certainly much easier than many other projects. The entire process, installing the new plumbing and removing the old, took a total of about 20 hours. And that was taking my time and included breaks for head scratching. The results have been a major improvement and the water is flowing as expected once again.

While working on the plumbing, there were a few other modifications I wanted to make. The design of the galley sink on this boat has always been a matter of consternation. It's made to have an insert sit over the sink to give more counter space. But we don't use the insert and what it did was make a space where water sat and couldn't drain off into the sink. It's a poor design and we even considered replacing the sink with one that surface mounts on the counter. But finding one that was deep enough and a size that would fit had been impossible, so a modification to the existing sink was in order. The answer was simply to fill in the space with decorative ceramic rope trim. The edges were taped off to keep everything clean, and the ceramic was set in a latex grout. The grout also filled the space between the trim pieces.

The galley sink also got a new single-handle faucet. Susan didn't like the old double handle when cooking and washing dishes.

While we were at it, the wood behind the sink has been stained with water and no amount of sanding or varnish was going to make it look better. A row of bull-nose ceramic tile to match the trim around the sink was perfect. The bottom edge of the tile was caulked using a silicone caulk to seal it and to keep water from getting between the tile and the edge of the counter against the bulkhead. Then, the tiles were grouted for a nice, finished look. We used a bisque color for both and it went well with the surrounding teak.

Susan was very happy with the results and that is the important part. It's amazing how much of a difference just a small project like this can make to brighten up the galley and correct what had been a nuisance.

We didn't want to head to feel left out, and the old faucet, which was probably original, was looking pretty shabby. So it now had a shiny new one. On to the next project.


  1. We have a 1981 Marine Trader 34 and need to relocate the cooking gas cyclinder from the upper bridge. Where is yours located and/or where do you recommend to pass survey safety inspection.

    1. Our tanks are still under the flybridge just as the boat was built. The boat has been surveyed a couple of times with no problem. If you have a surveyor that insists the boat be brought up to AYBC Standards, it will never pass on a number of reasons including this. Keep in mind that ABYC are Standards and not requirements. I have run into this problem over and over with surveyors. I was a surveyor once upon a time but it became too much of a hassle. Ask first before you hire a surveyor. As to safety, We have adequate vents in both side of the compartment and all opening to the underside of the flybridge are completely sealed. There is also a vent under the doors where the tanks are located. It's not perfect but it's what we have and how the boat has been set up for 30 years. I would highly recommend to have a propane sniffer installed that will shut off gas flow when it's detected. There is a CHB Yahoo group of MT owners. You might join and ask your question there also. Each of us has to make certain decisions when it comes to installation of equipment on board. This is my decision, yours may be different. I hope this helps. Chuck

    2. We think our tank has been under the upper flybridge for a long time too, and we have an electric solenoid shutoff with inside switch. We have louvered doors on the compartment. You're right that the surveyor wants the ABYC standards met and has been pretty hard on us. We're trying to get insurance and a new survey is required even for only liability. We had insurance in the past but let it go for a few years. The other surveyor in our area was in Dubai!! Have you ever shown your gas system in your projects? Where does the sniffer go?

    3. Too bad about the surveyor. These are the types that make life difficult for us. I would seriously do whatever I needed to to find another. Don't be afraid to do an "interview" before you hire one. Our set up is exactly like your. Electric solenoid with the switch on the front of the sink cabinet. I don't think we ever had the system on the blog. The best place for sniffers, I would get one that allows two sensors, is to have one under the flybridge if you have the space boxed in as we do, see the third photo down in this post, http://trawler-beach-house.blogspot.com/2008/12/and-beat-goes-on.html , it's almost right over the stove, and one right under the stove itself. Remember propane is heavier than air and will settle in to low spots. I hope this helps. Good luck.


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