Beropilacion de Aib yrerie,

10.1. Abstract

A common basic guide line characterizes all synoptic plant drawings: the target is to identify all the users and their position (bilges, living areas, machinery, tanks etcetera) and thereafter design the net of the necessary pipes, pumps and valves. The plans I shall examine are “synoptic”, meaning that they’re just functional schemes, in opposition to “topographic” plant which would show the actual position of each component. The latter is generally responsibility of the installer, under the designer’s supervision. Drawings called “as-is” shall be drafted at the end of the shipbuilding works: they are the actual on-board survey of the plants. The plants can be made of various materials: stainless steel, iron, copper, polypropylene, teflon, fibreglass: the material choice depends upon technical and economic considerations.

10.2. The pumps

The pumps have two main characteristics: the capacity and the head. The capacity is the amount of liquid that the pump can drive for unit of time: the unit of measure is litres per minute or m³ per hour.

The head is the height difference between the intake and the delivery points. The unit of measure is metres of water column. These values are in inverse relation: the same pump might drive more liquid at less height, or less liquid at greater height. For example: the data from a pump-builder technical sheet state that the same model has a 0.9 m³/h capacity with 10 m/H₂O head, or 2.7 m³/h capacity with 2 m/H₂O head.

The designer must keep these criteria in mind while choosing a set of pumps for a vessel.

Therefore a high head pump shall be used for firefighting purpose, as the water must reach areas of the ship much higher than the engine room, where presumably the pump is placed. On the contrary, a low head pump can be enough for the bilges service, as intake and outlet points are about level.

Pumps aboard a vessel must be self-priming: that is to say, the pump must be able to suckle liquid even if the intake pipe is empty. It’s a fundamental feature: on the contrary, the crew would have to manually fill the pump body with liquid in case it’s been out of work for a long time. Most of the pumps are electric driven, by means of a dedicated electric motor: they can be fed by 12 or 24 V. d.c.

or 220 or 380 V a.c. It mainly depends from the pump dimension and from the electric plant on board.

Some pumps are mechanical, driven by the MMEE.

10.3. The bilges drain

The bilges are divided by watertight bulkheads which separate various compartments of the vessel (see figure # 52). Some water usually drips from condensate, from the sea chests, from small spill from the machineries, from fortuitous shipping of sea water. In each of the vessel’s compartments there must be a bilge suction rose, that is to say a pipe connecting the bilge with the pump, with a filter at its end to stop solid debris. In figure # 52 I have enlarged the pumps area. Please note that there are two bilge pumps: they can work together or one can backup the other. The suction roses are connected to a manifold with non-return valves. The bilge water flows into the sea, but for the engine room bilge water which is supposed to be oily and must be collected in a dedicated tank. All plants drawings must include a legend (see figure # 53) which explains the symbols, lists the machinery and possibly the dimensions. A high capacity mechanical bronze pump should be prudently installed on one of the MMEE: quite useful in the unfortunate case of engine room flooding. For the same reason, a three ways valve can be installed on the main sea water intake pipe: this valve allows the MMEE to suckle the cooling water from the bilge instead that from the sea. It’s an emergency item only, to be used in case of major leak.

Fig. 52

Fig. 53

10.4. The fresh water

Structural double bottom tanks hold the fresh water. The water is boarded from the pier through large size pipes, placed on both the vessels’ sides. As all boarding pipes, they must be provided with ventilation pipes. But fresh water is also produced on board by means of reverse osmosis water makers. We’re talking of electric driven machinery which purifies sea water, making it drinkable.

Their output capacity ranges from a few hundreds litres to some thousands per hour: boarding water from the pier becomes therefore useless. The fresh water that they produce is collected in the tanks and once they’re full, the excess production is discharged overboard. In fact it’s convenient not to stop and restart the water makers too often to keep them in top shape. The fresh water pump is fitted with a surge tank: this keeps a constant pressure and smooths the impeller’s pulses, so the water flow to the taps is continuous and uniform. Also the fresh water pump should have a backup pump, so that the fresh water supply is granted also in case of failure or maintenance of the main pump. It’s plain that the fresh water pump must have a sufficient head to grant enough pressure also to the top decks users. Hot water must also feed the wash basins, the bidets, the showers, the tubs, the kitchen: the warm water comes from one or more boilers. The water is heated by means of electric resistances and/or by means of exchangers with the heath of the gen sets cooling water outlets. Large vessels should be provided with a hot water circulating pump: this way the hot water is immediately available, also on upper bridges, avoiding long waits. The designer should not forget some users which are peculiar for vessels, such as a shower on the aft bathing platform, a wash basin in the engine room, the water supply to ice makers, the deck pools, the windshield washer. Decks washing on large yachts is done by means of fresh water: in this case a water sweetener is appropriate: the water, devoid of calcar, won’t leave unaesthetic white stains on the vessel’s paint.

10.5. The deck washing

The crew washes the decks either by sea water or by fresh water: all experienced Captain knows that the teak planking must only be washed by salt water. A sea water pump is therefore necessary:

it’s also used for washing the mooring chains: they might be messy with mud, sand, algae coming from the sea bed and would dirt the deck and the chains locker. The deck washing pump can be used to back-up the firefighting plant in case of emergency.

10.6. The firefighting

Fire on board is possibly the worst nightmare of all sailors. For this reason the vessels are fitted with several fire prevention and extinguishment means. The simplest are the manual fire extinguishers: their number, capacity and position follows the Registers rules. In principle they must not be hidden inside lockers, or in case they are, their position must be clearly identified by a dedicated sign. There’s a main firefighting plant: the outlet pipes end up in boxes, assigned for the purpose, placed around the decks in strategic positions. Fire hoses are placed in the same boxes. All cabins and rooms on board a vessel are provided with one or more heat and smoke sensors:

automatic water sprinklers are installed on every ceiling. The engine room is fitted with a carbon dioxide automatic and manual remote-control firefighting plant: the gas bottles are placed in a dedicated room. I already wrote in 9.4 about the automatic or remote-control shutters, to cut- off air in case of fire in the engine room: the same principle applies to the fuel pipes, which valves must be shut to cut-off fuel from the engine room. The Registers require that some vessels are fitted with a portable emergency pump, equipped with its own independent engine and portable by two people.

10.7. The fuel supply

I wrote in 8.1 that the vessel is fitted with structural double bottoms, which host the fuel. Besides the main tanks, there’s a smaller reservoir, placed near the MMEE, called “daily tank”: the MMEE and all the machinery are fed from this tank. The fuel is carefully filtered before it gets to the users:

the filters remove water and other impurities. Larger vessels are fitted with one or more rotary filters:

this machinery pumps the fuel in a filter, round the clock, also when the vessel is moored. It draws the fuel from the furthest tank, filters it and pours it in the nearest tank. Condensate water and sludge might gather in the tanks bottom: in a calm sea the water, which is heavier than fuel, would not create problems. But in a rough sea, as the vessel rolls and pitches, the water might mix with the fuel, thus reducing the MMEE power or even stopping them, right when the crew needs all the available power to fight the bad weather. Please see 3.4: as I wrote, roughly 10% of the fuel cannot be used, as it fills the pipes, the filters or remains in the tanks bottom. The MMEE don’t use all the fuel that the injection pumps suckles: some of it goes back to the fuel tank. It is hot and a good idea is to connect this excess line to the farthest tank, so that the fuel has time to cool. The fuel tanks are all connected and the crew, by means of a dedicated pump, can move the fuel from a tank to another. Like this the crew can control and adjust the vessel’s trim.

10.8. The black waters

The international rules don’t allow any vessel to release the WCs black waters into harbours or coastal waters. The vessels are therefore provided with sewage tanks and treatment machinery. The black waters tank is fitted with a level alarm, although it must be emptied only manually by the crew.

The black waters must be discharged into a cistern aground, through a dedicated collector. Like all tanks, also the black water tank needs an outlet air vent which, for obvious reasons, must be placed as far as possible from the areas dedicated to guests and crew. A good idea could be through the mast top.

10.9. The electric plant

The sources of energy are essentially three: the batteries, the electricity supply from the pier and the diesel-electric generators. The batteries are gathered into gas-proof boxes: they’re used for the MMEE start and as a source for the 24 and 12 V. d.c. lines. The Registers require, for some types of vessels, that an emergency set of batteries is fitted on board. This set is bound for emergency radio communications and lights. As an alternative to the batteries there must be an emergency generator, placed on the highest bridge and independent from all the other energy sources. The pier supply is alternate current. Some of it feeds directly the a.c. users and some, by means of a rectifier, charges the batteries and feeds the d.c. users. Finally the diesel-electric generator feed the ship with all the electric power she needs. The electric plant on small vessels is generally quite simple and all d.c, either 12 or 24 V. On large yachts, on the contrary, the plant is 220 V, a.c. In each cabin or group of cabins there might be a rectifier to allow the use of d.c. users, such as the lights. Only very large vessels use 380 V a.c. The choice of lamps is quite wide since we stick to d.c. There are several producers, building high quality and lovely design lamps. Unfortunately the same doesn’t happen with a.c. lamps, but the designer can easily put the issue right by placing local rectifiers and going back to d.c. lamps. The electric plant has a general control panel which is usually placed in the engine room.

Please mind that it might be quite large and heavy. There are also secondary control panels, for each group of cabin, out of which the most important is in the pilothouse. The electric plant should be built in sections, each leading to a control box. A dedicated colour and label marks each wire. Let me machinery called “primary air treatment group” filters the external air, dehumidifies it and minimally

cools it. The air is then lead into the cabins by means of high diameter insulated pipes. Once the primary air fills the rooms, it is cooled (or warmed) by the air conditioning plant. A set of chillers and pumps is placed in the engine room, while each cabin is fitted with one (or more) local machinery, called “fan coil”. The air conditioning supplier shall help the designer choosing the number and type of fan coils, which power depends on the room’s volume and environmental conditions. It’s up to the customer to decide whether some particular rooms, such as the toilets or the engine room, must be air conditioned or not. All fan coils must have an air outlet and intake: they produce an incredible amount of condensate, such that these machineries are fitted with a tray below.

These trays must be connected to the white waters tank. A thermostat for each cabin controls the temperature. The designer shall indicate its position on the plans: it shouldn’t be near the portholes, neither near the fan coils and in any case it must be visible and accessible. The fan coils, as well as the primary air pipes, are quite voluminous. Therefore the designer must carefully plan their position.

10.11. The lockers ventilation

Every closed volume, such as bilges, chain locker, carbon dioxide room etcetera must be sufficiently aired by means of ventilation ducts and openings. This way the vessel won’t stink of damp, the rooms shall be healthy and the vessel’s structure will last for long.

Chapter 11