Domestic Systems


Bilge Pumps & Bilges

A normal arrangement is to have two bilge pumps, one on stand-by all the time and generally with a green light on to indicate the pump is ready. The circuit for this pump bypasses the normally switched circuits on the panel.

When the boat and the DC system is shut down, this circuit remains live to power the pump in automatic mode. This bilge pump is possibly never used; however, it is set to come on when there is sufficient liquid in the bilge to lift the float switch. This switch can be tested manually by lifting the float, and the pump should start. The other method is to fill a bucket with water and put the pump into it; the float switch should activate the pump and discharge the bucket's contents overboard; this proves the discharge pipework is clear of bugs, nests etc.


To help keep the bilges dry, keep a stock of infant nappy pads (ie Pampers); they are very useful to put in the bilge where liquid of one type or another accumulates. Just leave a nappy pad in the area; over time, it will absorb and grow to the size of a football.

Keeping the bilges clean will remove most of the oily smell and other smells that can permeate the boat over time.


Black Water Tanks

Black water tanks are to take and store effluent from the boat's toilets. Depending on the size of the boat and the number of toilets aboard, generally, one black water tank per toilet; if the toilets are close to each other, then one tank. A black water tank at each end of the boat is on a typical layout of forward and after cabins with toilets.

Pump-out deck connections are generally on port and starboard upper deck side walkways.



The calorifier is the boats domestic hot water heater, hot coolant water from the main engine circulates around the inside of the calorifier transferring heat to the incoming cold water. When the engine is shut down the 240 volts AC system supplies electric current to a heating element inside the calorifier.  When not connected alongside, run the main engine for an hour or two to give hot water and recharge the batteries.


Central Heating System

Wet System (Diesel)

For an average 40 to 50 ft boat, a 10 kW wet system, ie the Kabola range, will give you 6 to 8 double radiators. Keep pressure in the system at 1.2 to 2.0 Bar (refer to handbook); use a hand pump to pump up the system with a mixture of anti-freeze. Another method to increase the pressure is by connecting to the pontoon freshwater system, this will give you the desired system pressure but will reduce the efficiency of the anti-freeze.

The circulating pump needs a 240-volt supply; through the inverter, 12-volt pumps don't seem powerful enough. Keeping the circulating water at the correct freezing temperature for your cruising area is vital. Your Boatyard should have a little test kit that will give you the freezing point of the circulating water.

The diesel fuel supply for the heater is generally from a separate red diesel tank. Red diesel is mainly for commercial use and cheaper to buy than white diesel. Red diesel has a dye that leaves a mark in the diesel system that customs officers can see.

Using red diesel in heating systems on boats in the European Union is ok.

Wet System (Gas)

An LPG gas boiler, and as mentioned above, keep the pressure in the system and ensure the anti-freeze mix is the correct freezing point for your cruising area.

Blown Air Systems

Various blown air systems are available for boats; all seem to work off the same principle, blowing air over a heated surface increases the temperature. This heated air is blown through large bore flexible pipes out through a grill into the accommodation areas.


Dogs and Cats On Board

If your dog has not been to sea with you, get him acclimatised to the boat whilst alongside for a couple of days, this will get your dog used to all the different smells and noises, then go for a short trip.

Don't forget to have a lifejacket ready for him and get him to wear it, have a long lead clipped on in case he falls overboard; for small dogs, buy a good quality fish landing net with an extending handle, should he fall in the water. Your dog could suffer from dehydration at sea from being in the sun without shade. Ensure bowls of fresh water are available for him. Have plenty of fresh water and food available onboard.

Moggies have been 'Ships Cats' for centuries and can quickly adjust to life aboard. Cats need to practice swimming and have a few lessons; if not, a fish landing net like the one above may come in handy.

Ensure you have adequate medication and specific pet related sunscreen (most human sunscreen is poisonous to animals); shorthaired dogs and cats can get sunburnt. 


Gas system

The LPG gas available on boats is either Propane or Butane.  In some countries, the colour of the gas bottle is misleading; check which gas you are using. 

On boats, propane is the preferred gas; it has a different boiling point than butane, i.e. propane is still usable up to around -40c, while butane will stop working around 0c. Propane bottles can be kept in an outside locker.

The next problem with the different bottles is the unique gas regulator that only fits the type and makes of the bottle. Camping Gaz is available throughout Europe. In France, they have a Twinny, slightly bigger than the camping gas bottle.

The gas bottle must be kept in a ventilated locker, ie. The base should have hole(s) where the locker can vent directly overboard should there be a gas leak.

Most boats have a solenoid valve in the gas locker to shut off the gas remotely; this solenoid valve is connected to the boat's DC system and operated from the galley.

The gas pipe should run as one continuous copper pipe (protected) to the galley, where the gas goes through the separate shut-off valves to the hob and oven.

The hob and oven burners must be fitted with flame failure devices (FFDs).

A gas leak detector is a boating safety requirement, fitted near the oven/hob and tested regularly.


Mosquito Nets

Mosquito nets really do help the comfort factor of the people onboard. Mosquito nets can be made up on board initially by using net curtains or buying the correct ones from a chandler to fit overhead hatches and port lights.

At one time Ikea sold a mosquito net that went over a garden pergola and worked very well in covering the whole after deck of a motor cruiser or cockpit of a sailing boat and, with a bit of snipping and  tucking, looked the part. A domestic door mossie net with magnetic clips works very well on sliding door arrangements.


Rats and Mice

Having a rat onboard can be very worrying. Rats will chew electric cables and plastic water pipes if they can't find food.  There are various methods to keep them off the boat; big ships use a tin plate, like the top of a round biscuit tin, that fits over their mooring warps to stop rats from running up the warps.

In some ports, rats are often seen under the shoreside electric/water box, ready to jump aboard! Pontoon berthing is undoubtedly much safer. If berthing in the Med stern too, try to 'lay off' and use a boarding ladder that can be lifted on and off the quay after boarding or going ashore.

In all cases, carry a couple of mouse and rat traps on the boat.


Satellite TV Systems

A satellite TV system can operate successfully on a boat with the right size dish, the correct digital box, and the Satellite dish pointing in the right direction. There are various devices to help pinpoint the correct Satellite.

The option now available to boaters is the automatic selfseeking all-enclosed Satelite dish; it costs more than the basic dish but is well worth the money,



The shower tray will either discharge into a small holding tank with an automatic bilge pump type  of arrangement or be pumped overboard through a gusher pump. In both cases the discharge can be directed through a ‘Y’ valve to go overboard or into a grey water tank.


Toilets/ WCs

Macerator Electric Toilets

Macerator toilets are powered by the boat 12 or 24 DC volt systems.  Water supply to the toilet can come from the boat's fresh water tank or the water outside the boat. Using the boat's fresh water supply is the usual method.  Toilet discharge through a 'Y' valve can be directed overboard through a sea cock, or into the boat's black water tank.

Pump type toilets

These toilets draw their water from outside of the boat and can discharge through a 'Y' valve into a black water tank or overboard through a sea cock.

Vacuum Toilets

Typically the Blake Lavac Toilet - After use, close the seat and lid to complete the sealed unit. The vacuum formed draws in replacement flushing water to clean the bowl.



Ventilation is essential on a boat, and it is an aid to comfortable living afloat. Keeping air circulating throughout the boat can be done by fitting small vents to doors and locker lids.

Engine room ventilation is by vents on either side of the boat to supply the main engine when running.

There are a variety of fixed vents that can be fitted to the coach roof, some controlled by solar power. Dorade vents look the part but are expensive.


Washing Machine

The washing machine takes its power from the 240 volt AC ring main.

The water supply to the washing machine is from the boat's freshwater system. Discharge overboard is usually above the waterline.

Rapid wash is the best setting to use to save energy and water. The washing machine warm-up cycle draws considerable AC power, and consideration should be given, especially if not connected to shore power, that an overload situation might occur whilst using the inverter on ships batteries; it will need extra power from the generator or main engine, or just use it when connected to shore power.

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