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Lesson Learned: Disappearing Water

Sunday - October 25, 2015Views: 766Taken at Mamaroneck, NY
Warning: Long essay follows on how I discovered a simple solution to what I thought was a major problem. Old-timers on the list will see how foolish I was. I'm posting this so the new-timers can avoid the time and worry I went through! The essay is called "Believe Your Boat."





Believe Your Boat

We all spend so much time maintaining the myriad of systems on our boats. Why when something goes wrong do we blame the boat and jump to the conclusion that some part has failed? Maybe you don’t do this, but I did recently and feel foolish for having done so. Here’s what happened.

In July I sailed up to Newport from Mamaroneck. It’s about a 22 hour trip on my IP27 “Turtleheart.” We sailed most of the way up: 17 hours from Mamaroneck, through the Race at 0400, and then along the R.I. coast until about 0800, when we turned on the engine and motored the rest of the way to Newport at 5 knots with the engine at 2500 RPM in torrential rain and 2-4 foot seas. No problems. We did the trip back in two legs, Newport to Westbrook and Westbrook to Mamaroneck, and with the wind on our nose we motored nearly all the way, about 11 hours each day. We had one hour of sailing on the very end of the second day.

On the way back we noticed that our fresh water tank had emptied, even though we’d barely used the taps. There were no obvious leaks, and the bilge was empty. I don’t have a bilge alarm or counter, and had no idea that the bilge had cycled. I made a note to check more carefully after our return, and I did. I found about an inch of standing water in the downhill corner of the storage area under the quarterberth, but couldn’t figure out how the water had gotten there. I filled the tank and ran the taps; nothing. I took the boat out, motoring for a half hour or so to duplicate our travel conditions and lo and behold, water appeared under the quarterberth. The only possible source: the water heater. Still motoring, I removed the access panel at the rear of the quarterberth and discovered that the pressure/temperature relief valve on the water heater had opened, spilling water into the bilge.

My first thought was that the relief valve was broken. I’d had no indications of the engine overheating to or from Newport. I called the manufacturer (Seaward), who told me that these valves do fail over time. They suggested that I buy a replacement and told me how to remove the old valve and install the new one. Before ordering the part, I began thinking: what if it’s not the valve? The water heater valve opens at 210 degrees. The engine temp alarm on my Yanmar 2GM20F goes on at about 203 degrees (the green-coded sender closes at 193-202 degrees). What if super hot coolant was getting to the water heater and setting off the temp relief valve? Seemed unlikely, but I decided to motor out and check the engine temps.

I did so. The coolant pump/thermostat housing was about 135 degrees shortly after startup at idle (850 RPM) and about 165 degrees once underway for 20 minutes or so (at 2500 RPM). (These temps are, of course, on the outsides of the various parts, and I don’t know how accurate they are.) The alternator and transmission housing were about 135 degrees. The large elbow at the back of the heat exchanger (the cast iron fitting) and the small elbow on top of the heat exchanger (for the exhaust hose to the U-shaped mixing elbow), were off the charts – reading over 400 degrees on my IR thermometer. The engine wouldn’t run higher than 2700 RPM without throwing off heavy black smoke.

Naturally, I thought the mixing elbow was corroded, or the sea water pump was defective or needed a new impeller, or the heat exchanger wasn’t working and needed to be removed and cleaned, or the thermostat was broken, or the engine temp sender was defective, or some combination of all of these.

And here’s the point I want to make: I was convinced that one or more of these water heater or engine parts had failed notwithstanding that the boat is serviced and maintained meticulously; notwithstanding that I never use the water heater; notwithstanding that the mixing elbow and sea water pump impeller were only a few years old; and notwithstanding that the engine had its full 1000-hour servicing last summer that included flushing out the cooling system and putting in a new thermostat. I began reading the 2GM shop manual to figure out what might need to be done, and to figure out who I was going to call, and when, to get the job done without ruining the rest of my sailing season. Not until I’d had plenty of time to think about all this and to calculate how much it would cost did I consider that maybe the boat didn’t fail me – maybe the problem was outside the boat. Maybe my prop was fouled and this was causing the engine to labor, overheat, throw off black smoke above 2700 RPM, and send super hot coolant to the water heater, tripping the relief valve and sending fresh water into the bilge.

You know the ending to this story: I dived to the prop, discovered the barnacles, scraped them off, and took her out for another test run. Full power to 3000 RPM, no problem getting to 6 knots, no black smoke, mixing elbow at 200 degrees, happiness all around.

Moral: Don’t assume that your well-maintained boat has failed you. Assume everything is working as it’s supposed to and figure out what else could be causing the problem. Remember your prop!

And the upshot: I installed a drain hose on the water heater relief valve, so if this happens again, the water will go deep into the bilge and not flood my quarterberth. Photos attached.
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The International IPYOA administration team.