At Nanaimo Boat Yard we provide an extensive range of yacht services and our team at the marine store will offer their advice and experience if you are tackling a job on your own. We stock all the components you need to do your own plumbing. We stock TruDesign Plumbing components and products from other manufacturers too.
Boat plumbing on small boats can be relatively simple because there aren’t rigid pipes, it is all flexible tubes. There are a few key areas to boat plumbing:
It should be common sense, but just in case….as water is heavy, any tanks should be mounted as low as possible in the boat otherwise you will affect the stability of the boat. Rigid polythene tanks are available in different sizes and shapes or if space doesn’t allow a rigid tank then you can buy a flexible “bladder” tank which you can put into an awkward space. A typical water tank will have 3 threaded ports; an outlet, a vent hose and a fill hose. The inlet is connected to an on-deck fill which must have an O-ring to seal out seawater. The vent line must lead to a vent fitting high in the boat to ensure whatever angle the boat is sailing at sea water will not fow in. Remember to ensure the vent is higher than the fill hose otherwise the vent will simply overflow. The outlet connection should lead directly to a pump or if there is more than one tank to a Y-valve.
It’s a good idea to use a recommended thread sealant on all threaded fittings and be careful not to overtighten fittings in plastic tanks. Hoses can be securedwith fittings using stainless steel hose clamps.
For boat plumbing you need to use recommended hoses otherwise the water may taste foul and worst still may be toxic. Piping must be non-toxic, non-contaminating and FDA approved for drinking water. If the water is going to be pressurized or will be carrying hot water then the piping needs to be checked for whether it is fit for purpose.
Semi-rigid polythene (PE) tubing has become increasingly popular for boat plumbing. The advantages of PE are quick connect fittings and that it comes in different colours so not only does a color reduce algae growth but it also means you can come up with your own color coding e.g. red tubing for hot water and blue for cold. Having the tubes color coded may make all the difference if you’re trying to identify problems later on. The PE tubing is cheaper, but is a little trickier to install because it is less flexible and will need to be cut to the correct lengths.
Drain hoses which go through the hull should be made of reinforced rubber hose. This type of hose is also used in engine plumbing as it has a much higher burst strength. Any hoses which are connected through the hull should be double clamped.
Depending on the size of the boat you can decide whether the water pump should be electric or manual.
An electric pump will pressurise the entire water system. The standard set up is a pressure switch that activates when the water pressure drops below a pre-set range. Normally this is around 30 to 40 PSI. When a tap is opened it releases pressure andso the pump kicks in and then keeps on going until the tap is closed. The pump will then cycle on and off until the tap is switched off. The inlet of an electric pump connects directly to the tank outlet which then supplies water to all taps.
Manual pumps can be hand or foot operated. Water flow is controlled by the operator of the pump and so the amount of water used is dramatically reduced.
Some plumbing systems have accumulator tanks. An accumulator tank is a water chamber which has a pre-pressurized internal air bladder. When the pump runs it compresses the air trapped inside the tank and so allows small amounts of water to be drawn without having the pump running.
In order to have hot water you must be operating a pressurized water system. The pump pulls water from the storage tank and fills the water heater tank. The water heater tank is simply a tank with an electrical heating element and a heat exchanger. When AC power is available, the electrical element (controlled by a thermostat) heats the water. When AC power isn’t available ( once you’ve left the dock ) then the hot engine coolant is routed through the heat exchanger to heat the water in the tank when the engine is running.
Water heaters have the following ports:
If a pressure-release valve isn’t integral, the heater will have an extra port.
Manual pumps require simple spigots. Pressure water systems there is no real difference between land based taps and showers. The only small difference is that boat taps and showers are fitted with hose barbs.
Sink drains are normally simply connected to a reinforced rubber hose which goes through a through-hull fitting. On sailing boats sinks are therefore best located high up so heeling doesn’t put the sink below the waterline. Showers are often set up so that they drain into the bilge which means the water then needs to be pumped out by the bilge pump. Ideally, we recommend isolating shower drains from the bilge with their own discharge pump. This way you avoid blockages and unpleasant bilge odors. The through-hull discharge outlet must always remain above the water.
We’re here to support you doing your own plumbing or if you’re not sure you can always use our yacht services team.