Call For a Tow


By Tom Neale, 11/16/2006


Tom Neale's logs have a new name and home on BoatUS Magazine. We know Tom has a loyal and devoted readership, so we wanted to share his tips and insights with an even bigger audience! For the latest articles, click here for Onboard With Tom Neale.

Detective Tools
You’re lying there in bed at night. The wavelets ripple along your hull. The wind sighs in the rigging. You begin to drift away into sleep, lulled by the sounds of the boat at rest in the night. Then you hear the water pump come on. Many boats have several water pumps, but this sound is unmistakable. It’s the sound of the water pump that brings all that nice fresh water up from the tanks and into your shower, your sink, your glass.

You groan, get up, and go around the boat looking for dripping faucets. Surely someone didn’t turn one off all the way and this is NOT A PROBLEM and you’ll be able to go to sleep soon. To your dismay, every sink is dry. There are no drips. Even when you hopefully run your fingers under the faucet openings, they come away with no moisture.

“Must have been one of those little coincidences you get on a boat,” you think. “Maybe the pump was on the verge of going off when it was last used and that pressure switch didn’t make the last thousandths of an inch of movement at the time. You lie down again, close your eyes, start trying to forget it, and drift off.

You sit up this time. You’ve heard it again. How could this be happening? You know the answer; you’ve been there before. It’s a leak in the plumbing somewhere. Maybe it’s under a sink where the space is hardly big enough for the cockroaches that sometimes end up there. Maybe it’s in the engine space, ensnarled in life threatening hose clamps. Maybe it’s deep behind a cabinet. You smile. Maybe you’ll finally get to use your new SawZall. Maybe it’s where the plumbing runs right over the new CD/DVD player. Never mind. The problem can only be dealt with in the daytime when there’s good light. Because first you’ll need to be able to find the water dribbling down into the bilge so that you can zero in on the leak to fix it—you hope. At least you’re in a marina and plugged in. You’ll be able to get parts if needed and use trouble lights and simply get off the boat if you get tired of dealing with the problem.

You drift off into sleep again. What’s that??? That wasn’t a pump. It wasn’t a fish jumping outside. It’s certainly not raining outside. That was the sound of water splashing into the bilge. Not just a little drip. It was a lot of water. And it was indeed splashing. Then the pump comes on again, but it has a distinctly different sound. It’s not the water pump. It’s the BILGE PUMP. The worst fears of a tired boater in the middle of the night have just happened. The bilge pump is on and the water you hear splashing into the bilge sounds dangerous.

There’s no time for rest or even hesitation when something like this happens. You tear out of your sheets, open the engine space, and look for the deluge. But just before you get the hatch open, the sound of the splashing water flooding in stops. As does the bilge pump. You reach for your flashlight, look down in to the bilge, and nothing’s happening. Not even a ripple disturbs that little placid lake down there. Could this have been a nightmare? Maybe all a trick of the mariner’s mind? You want to convince yourself that it was, but you’re having trouble. You keep looking at the bilge, hoping yet not hoping for some sign of trouble. But nothing.

You look at the fresh water pump. It’s just sitting there, docile and in perfect behavior. No trips, nothing weird. Nothing unusual. You turn it off, knowing that you should have done it much earlier in the night. At least you can get some sleep now. Whatever is happening can’t happen with the pump off and you can always turn it on if you need some water.

You start awake around an hour later, to the sound of water splashing into the bilge. It has to be a nightmare. It can’t be happening. You scramble out of bed, running this time to the engine space, as you hear the bilge pump come on again. “Why the hell didn’t I leave the hatch open?” you ask yourself as you go for the flashlight and tear into the quiet space. Yes, “quiet.” As you look, you see no running water and the bilge pump has quit.

About Water Heater Pressure Relief Valves

1. We’ve found that these valves are much more likely to open on boats than the ones in houses. This can be caused by the fact that many boats have water heaters that operate not only by electricity like those in homes, but also with a heat exchanger through which the hot water in your engine passes to heat the water in the hot water tank.

2.There’s less temperature control with this system than with an electric thermostat controlled heating element, so there’s more of a likelihood of higher pressure occurring from time to time.

It’s time for a stakeout. Pouring the last dregs of coffee from the previous morning’s breakfast, you settle down to wait, determined to not take your eyes off the bilge. Around 4:00 a.m. it happens again. You’ve fallen asleep crouched in a corner, cold and sore, but you’re there. As your eyes fly open you see disturbed water in the bilge and hear new water pouring in. But from where? With your butt in the air, you lean as deep down as you can as the water stops again. And you see the open end of a hose—hidden up out of view, and it’s dripping. Just a little.

Getting tired of this mystery? I certainly was when it happened to me. Filthy, ticked off, tired but wide awake, I decided to trace the hose. It wasn’t easy, of course. So many builders seem to relish the thought of impossibly obscuring, camouflaging, hiding and/or covering over anything they can. But I did trace it, and finally found the end at the hot water heater, attached to its pressure relief valve (often called “pop-off valve.” As I watched, this valve hissed a little and a load of water splashed into the bilge.

This is a problem that has plagued many people, some of whom have spent small fortunes trying to troubleshoot it through “professional” help. But all it involves is the normal working of a small piece of equipment designed to make us safer. Like so many other problems on a boat, it’s not a big deal if you’re familiar with it.

Water heaters are required to have safety valves to keep them or related plumbing from bursting. Water expands as it gets hot and, should the temperature rise to a dangerous point, this could happen. If you were in the area you could be severely scalded. When the valve opens, it emits water and/or steam. To protect us from this event, an appropriate hose should conduct the emission away to a safe area. In a boat, this is often into the bilge. As the pressure is relieved, the valve closes again and the water stops flowing. For some tips about this problem, see Tom’s Tips below.

Copyright 2004-2008 Tom Neale