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The modern cruiser is well-equipped with an array of fittings and appliances which provide hot and cold running water, full cooking facilities, central heating and air conditioning which provides for comfortable accommodation.

Marine Heating Systems

The popular method of [ central heating ] in boats of all sizes is ducted air warmed by a diesel oil burner. The oil is supplied from the engine fuel tank, with the draw pipe set higher in the tank than the engine supply pipe to prevent the total consumption of fuel. The heater is started and controlled electrically and the fresh airflow is forced through the ducting by a fan.

Other methods of marine heating include wood stoves made of stainless steel and charcoal stoves. Charcoal stoves are still common due to their safety, compactness and simplicity; a combusting layer works its way slowly up through a cylinder of charcoal, and the heat it produces radiates from the metal casing. Paraffin, petroleum spirit (SBP) and bottled gas are also used.

When combustion heats the cabin air directly, it has the disadvantage of producing water vapour equal to the weight of fuel, and so to reduce humidity there should be good ventilation. For safety, gas and spirit heaters are of the catalytic form where the fuel passes over platinum gauze which glows hot, and there is no naked flame.

Marine Air Conditioning

Marine air conditioning units are used in motor vessels and the larger yachts, similar to those used in road vehicles. They consume electricity at a level only available by continuous engine running or the use of shore power. A sailcloth wind scoop is effective for directing breeze down the fore hatch on smaller yachts. At sea, sailing yachts rely on natural ventilation through the Tannoy vents or deck cowlings with Dorade boxes, designed to pass air while intercepting water.

Marine Stoves

Marine stoves vary from the simplest [ paraffin camping stoves] to [ split-level cookers] of the domestic type. Bottled gas marine stoves are commonly used because of their convenience and low fuel costs but need careful handling because the gas is heavier than air.

Leaking gas will accumulate in the bilge and form an explosive mixture as well as asphyxiation to those asleep. Although the danger of this is not as high as it once was, due to the introduction of 'flame-out' protection on marine stoves and gas bottle lockers that ventilate overboard, a reliable gas alarm should be fitted to warn of any leaks.

Paraffin Pressure Stoves

The alternative to gas cookers that are going to be used at sea, is a paraffin pressure stove. These are effective but a drawback is the burner needs heating with methylated spirit for a minute each time it is started and the fuel is generally costly.

Large yachts with the ability to produce kilowatts of power, or spending nights in a marina with accessible shore power, enjoy all the conveniences of domestic-style electric cooking. A alternative to an electric cooker is the microwave oven, which is suitable because its total power consumption is small and even a small yacht can run its engine and alternator for the few minutes a microwave takes to complete each cooking operation.

Marine cookers differ from those in the domestic market in several ways; firstly the materials should not easily corrode, and the whole unit should be gimballed in the roll axis of the vessel. With movement of a boat at sea, utensils slide or even jump off the stove unless constrained by frames called 'fiddles' being at least half the height of the utensils.

Good cooker designs, have retention of grill pans and oven trays, whose contents can cause injury if spilled by the motion of the boat. The pressure cooker is a preferred utensil at sea because, being sealed shut during use, it does not spill its contents and also efficient in its use of fuel as well as keeping food items hot.

Marine Refrigeration Units

Marine refrigeration includes designs similar to camping and domestic units, and are operated by gas, thermoelectric or compression systems. The [ compression marine refrigeration systems ] have low electrical consumption, and one type suited to any motorized boat has 'eutectic plates', inside the cool box, through which Freon is pumped directly from a compressor on the main engine. Running the engine for at least 30 minutes each day, results in the thermal capacity of the plates maintaining normal refrigeration for 24 hours.

Peltier Cooling

The thermoelectric marine refrigeration unit comprises of a compact and easily-fitted, solid state unit consisting of air-cooled Peltier plates maintaining low, but not freezing temperatures in a cool box. The elements within the [ Peltier plates ] consist of layers of semiconductor material sandwiched between two sets of metallic strips. As an electric current is passed through the elements, heat is absorbed from the inner set of metallic strips and emitted to the outside of the peltier cooling unit by the other set.

The heat is carried away from the unit by the air cooling of the plates but if the plates are water-cooled, even lower temperatures can be maintained. However, Peltier plate refrigerators are not as popular as gas or compression types because they cannot produce low temperatures.

Marine Water Tanks

Water storage tanks, made of metal, GRP or flexible fabric, have very few contamination problems if the original water supply is good and light does not penetrate the tanks. Scouring annually with treatments based on chlorine is a sufficient precaution to ensure safe drinking water.

Mount marine water tanks so as to keep weight as low as possible and if there is no space for rigid tanks consider flexible marine water tanks mounted in small spaces. Tanks and piping must be supported and secured against movement. Tanks should have inspection covers for access along with vents allowing air to escape as they are filled.

Avoid clear plastic plumbing hose, as algae grows inside the pipe where the pipe is exposed to sunlight. Rigid plastic piping offers a range of valves, couplings, and junctions making the system easy to install. The simplest freshwater system uses a manual pump at the galley and head sinks and requires no power.

Small yachts increasingly have [ pressurized hot and cold water systems] but this increases water consumption, as well as adding to running costs and maintenance. When a tap is opened, pressure pumps sense the pressure drop and if an accumulator tank is fitted this pressure reservoir smoothes the operation of the system. This prevents the pump repeatedly switching on and off to maintain pressure making the system quieter.

Reverse Osmosis Water System

An ideal source of pure drinking water is by desalination of seawater taken a distance offshore. Desalination can be by evaporation, using the cooling water heat of large engines, or by using a marine reverse osmosis water system.

In normal osmosis a membrane allows passage of water molecules but not salt molecules. To understand osmotic pressure, think of the water molecules on both sides of the membrane which are in constant Brownian motion. On the salty side half the pores get plugged with salt atoms, but on the pure-water side that does not happen allowing water to pass from the pure-water side to the salty side.

Osmosis is why drinking salty water will kill. With salty water in the stomach, osmotic pressure begins drawing water out of the body trying to dilute the salt in the stomach eventually dehydrating the body causing death.

With a marine [ desalination reverse osmosis] water system, the use of the membrane acts like an extremely fine filter creating drinkable water from salty water. The salty water on one side of the membrane has pressure applied to it to stop, and then reverse the osmotic process and this requires a lot of pressure.

Marine Toilets

Ensure every member of the crew understands how the marine toilet works. Most marine toilets operate by hand pumping in sea water, flushing the bowl and pumping out waste. Reinforced hose is used for the pump's inlet and outlet and fitted with sea cocks. Some countries prohibit the discharge of sewage from yachts requiring an [ installation of a holding tank ] and this in turn is emptied at a marina pumping station.

Marine Chart Table

The [ marine chart table ] is stationed close to the companionway, enabling the navigator to communicate easily with the cockpit crew. It is a self-contained area out of the way of the main living spaces and the galley and all instruments and radio sets are situated there. The chart table should hold a chart folded no more than once, and stowage for navigation equipment with charts stored in the space under the chart-table top.

marine heating system
parafin pressure stove
marine stove
marine refrigeration unit
peltier plate
marine hot water system
reverse osmosis system
marine toilet system
chart table