Britannia, my 45ft twin-masted schooner, almost sank, not from storm damage or from hitting rocks, but from within. A water pipe broke in her pressurised shore water supply system while she was safely moored up in a marina in Cape Canaveral, Florida. I had forgotten to switch the shore tap off when I left her for the afternoon. It was the start of a harrowing few days.

Pressurised water supply systems are commonplace in many marinas around the world, especially US territories. The system involves a hosepipe that connects the pontoon water tap to a pressure-reducing inlet valve on the boat that reduces the power of the onshore mains water supply by around half while entirely pressurising the boat’s water system.

The benefit is having constant pressure in your boat’s water system, which means there’s no need to use a noisy onboard electric pump, no draw on your battery, and an even flow of water rather than a pulsating stream, that’s particularly welcome when having an onboard shower.

Britannia’s half-inch diameter plastic water pipes were the same age as the boat, more than 40 years old, with a maze of connectors, in a tangled mess at the bottom of the bilge. I was frequently repairing or replacing sections, which leaked or cracked, whenever the automatic bilge pump alerted me to it by switching itself on.

So, I was fully aware that the whole water system needed upgrading, but then so did a lot of other things aboard Britannia. It was always part of my routine to turn the water off at the dock tap whenever I left the boat, even for a short time. Whenever I left her for a few days or longer I would disconnect the hose at the dock entirely. This, however, was the one time I forgot.

Pump action

Returning to the boat after just a few hours away, I noticed that the air-conditioning had stopped, which was unusual, so I lifted a floorboard to check the water circulation pump, and had the shock of my long and varied sailing life. Water was sloshing around just inches below the floor beams.

I should have thought quickly enough to test the swill, to see if it was freshwater or saltwater, which would have pointed me to a possible source of the flooding. Instead, I dashed to the nearby engineering shop to implore them to help me ‘man the pumps’.

The owner rushed to Britannia immediately, trundling a massive gas engine pump with a very long 3in diameter hose. As soon as the pump roared into life I shoved the suction end into the flood water, which was still rising and now above the batteries and halfway up the engine and generator.

As the powerful pump took effect, cooler thoughts began to prevail and I tested the water with a finger. It was definitely fresh water. That was when I realised that the pontoon tap was still switched on. By now a crowd had gathered around, so, feeling suitably embarrassed, I had to ask someone to turn off the tap for me.

Assessing the damage

Even though the water was eventually pumped out completely, I remained in a state of shock. Worries about the damage and the cost overwhelmed me, especially as much of the equipment was brand new, with £700 worth of batteries and a £3,200 generator. Thoughts of what was now inside both the engine and generator motors made me feel queasy and I found it difficult to formulate a clear plan. So I put the kettle on.

I started to tackle the problem by unscrewing each battery filler plug in turn and testing the specific gravity. They were normal and the rims of the plugs were dry. It seemed that no water had got in, and fresh water might not have done serious damage anyway.

The engine dipstick revealed a layer of milky oil and water, as did the generator motor. Water could also be seen up to the filler neck in the transmission. I needed to get it all out as soon as possible.

When I opened the engine oil drain plug the pan filled with a creamy mixture of oil and water. The generator contained the same mixture, which I drained into a bucket. The transmission drain plug was inaccessible under the gearbox, so I used a quarter-inch tube and a small impeller pump to suck the oily mixture out.

I knew I had to start the engines as quickly as possible, so I rushed to a nearby garage and bought five gallons of their cheapest oil: little point buying good oil as I knew one change wouldn’t be enough. I also bought a hair-dryer to help dry out some of the electrics.

Luckily, the engine room blowers hadn’t been submerged, so I switched them on, which started a fast air-flow throughout the machinery bay and out of the stern.

By now it was late evening and the engines weren’t the only thing that was drained. I simply couldn’t face trying to start the engines, so I had a few beers and went to bed. I didn’t sleep well.

Florida sun

Next morning, I drained the engine, transmission and generator once more. It was time to bite the bullet. I said a little prayer and pressed the engine starter switch. Thankfully, my trusty old ‘Perky’ burst into life straightaway.

Some spare mooring ropes, stowed below, were totally saturated, so I dragged them all onto deck, where the fierce Florida sun soon dried them out.

Next came the forward electric toilet waste system motors. This is an approved method of converting waste into natural dischargeable slurry, which means there’s no need for a holding tank. It is a sealed system and the motors whirred into life immediately.

The water pressure pump also started up – and that was when I spotted the source of the flooding. A pipe had blown out of the pump’s connector, which was only a compression fit held together with a screw-on plastic cap. I repaired it and the system pressurised normally.

The aft electric toilet worked normally, and was the last of the electric equipment to check in the bay. I considered myself lucky that it had only been a freshwater flooding. Had it been saltwater it might have been a different story.

It took two full days to clear up and check everything thoroughly, but with all the systems running again, I felt Britannia was back to normal again – after a very close call.

Pressure protection

I don’t know how many years this episode reduced my life by, but the question now was: how to prevent it from ever happening again? There was no certainty that another pipe wouldn’t fail, or that I wouldn’t forget to switch off the shore water again.

The obvious thing, suggested by several well-meaning fellow sailors, was to not connect to a marina water supply at all, and just draw from my water tanks, re-filling them as needed. This would definitely prevent a recurrence, but the same might be said about a shore electrical supply, which everyone uses without a second thought, but which has been the cause of many a boat fire.

My wife and I love the advantages of a marina water supply, if only for the silence of it, so it was just a question of how to make it as fail-safe as possible.

The first obvious job was to re-plumb the whole boat with new pipes and more secure connectors. I found a suitable system in my local hardware store which is used to plumb houses, in place of copper pipes. I considered that if it was approved for inside walls it would be strong enough for my boat.

I bought two 100ft coils of 0.5in 160-psi pipe, for only £21 each – one coil was red for hot water, the other blue for cold. I pulled this new piping through the boat by taping it securely to the old pipes and hauling it through. I also re-routed much of it in a more direct way, so I could inspect it easily and get to the connections.

I then bought all the various connectors I thought I might need – elbows, tees, splices, etc. They are guaranteed up to 100-psi not to leak or pop out of the pipe. They are also very easy to connect: the pipe simply pushes into the connector and is locked by a barbed ring clamp and the waterproof seal made by an internal O-ring.

Colour coding

It took four days to re-plumb the entire boat, and the new installation looks very professional, having twin colours side by side and nice new connectors.

I found an automatic shut-off valve online for £43. I connected it into the inlet water line, directly after the pressure valve, and wired it to the boat’s bilge float. When the float is activated by the bilge level, the valve closes and stops any more shore water entering the boat’s system.

This worked fine, and I thought this was all I needed. However, when the bilge pump cleared the water, the float went down and the power to the solenoid also switched off, so the valve reopened itself, allowing water to flow in again, and the cycle would repeat itself continuously.

To stop this, I incorporated a ‘latching relay’ into the circuit. This is a 12-volt relay which, when the primary current switches off, the relay stays live, thus keeping the shut-off valve closed.

Later on, I calculated that 560 gallons (2,120 litres) of water had come in. With a gallon of water weighing a bit under 10lbs (4.5kg), the total weight of water would have been more than two tonnes. No wonder the old gal went down so far.

Fail-safe systems

Seeing your boat full of water is frightening, even when you are safely moored in a marina. If I hadn’t returned as soon as I did then the damage would have been worse. The dockmaster told me he’d seen two boats sink this way.

I decided to find out how many other boats in the marina used a pressurised shore water supply. I asked the owners of 12 if they had any safety system in place in case of an internal pipe failure. Amazingly none of them did. They all said that they remembered to switch the water off whenever they left their boats. Yep, so did I, and look what happened!

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