SHIP’S
DESIGN, CONSTRUCTION AND EQUIPMENT
There are
two main parts of a ship: the hull and the machinery. The hull
also includes the superstructure while the machinery comprises
not only the engines required to drive her but also the auxiliary
equipment serving the electrical installations, winches and
refrigerating plant.
The hull is divided into three areas: fore end, after end and
midships. The fore end is known as the bow(s) while the after
end is known as the stern. When we stand in a ship facing the
bow the left-hand side is called port side and the right hand
side - starboard side. The beam of the ship is the distance
between the two sides.
The hull includes the shell plating and all the members and
parts, which hold the shell together, divide it into compartments.
The shell plating is made up of a number of steel plates fixed
together. Each horizontal row of plating is called a strake.
The hull is also the area between the main deck, the sides and
the bottom. This area is divided horizontally - by decks, and
vertically - by bulkheads into a number of watertight compartments.
The deck constructed between three and four feet above the shell
at the bottom is called the tank top plating, because double-bottom
tanks are located here used for carrying fuel oil, water ballast,
etc. The transverse vertical plates dividing these tanks into
sections are called floors. Stringers are large beams or angles
fitted in various parts of the ship to give it strength. The
frames, which are the ribs of the ship, serve to give the ship
its form and support the shell plating. The decks are supported
by transverse and longitudinal members called beams and girders,
used as connections and strengthening pieces. Companion ladders
are designed to connect the different decks. The fore peak tanks
and after peak tanks at the fore end and the after end of the
hull are used for fresh water and ballast water.
Apart from these the hull contains the engine-room and cargo
space. In dry cargo ships the cargo space is divided into holds;
in liquid cargo ships - into tanks. The decks dividing cargo
spaces are known as ‘tween decks. The holds are served
by hatchways or mechanically operated hatch-covers.
A ship’s actual design and number of decks will depend
on the trade in which she plies. So, a tramp carrying coal or
ore will be a single deck vessel with large unobstructed holds
while a cargo liner carrying a variety of cargo will have tween
decks to facilitate stowage. Additionally, container ships are
equipped with specially designed holds with cells or slots to
facilitate container handling using shore-based lifting gear.
Deck equipment includes:
- cargo and steering gear
- anchoring and mooring arrangement.
The cargo gear comprises cargo space and cargo handling facilities,
such as derricks, cranes, etc. for loading and unloading cargo.
In case of some special perishable cargoes, ships are fitted
with refrigerated holds, too.
The purpose of the steering gear is to keep the vessel on a
steady course. It consists of a rudder which is situated right
aft, a steering wheel, a steering engine, an autopilot, etc.
On many modern ships there is a bow thruster which gives greater
manoeuvrability and so reduces the need for tugs.
The most important parts of the anchoring arrangement are: the
windlass used for lowering and raising the anchor, an anchor
chain which comes up from the chain locker through the spurling
pipe over the cable lifter on the windlass, through the cable
stopper and down through the hawse-pipe.
The mooring arrangement consists of a warping winch, bitts and
fairleads for the mooring lines.
Depending on the type of the ship it carries a crew and a number
of passengers. They are accommodated in single -berth or double-berth
cabins. All the accommodation is housed in the superstructure
and is fully air conditioned. The galley and the messroom are
located in the superstructure, too. The watertight superstructures
erected at the extreme forward and after end of the ship are
known as the forecastle and the poop.
The chartroom and the wheel-house are situated on the navigating
bridge, the topside structure built about midships. They are
fitted with modern aids to navigation. Radio communication is
handled in the radio-room either by means of transceivers or
INMARSAT and GMDSS facilities.
Lifeboats are arranged on the port and starboard side of the
boat deck. They are carried in davits and are used for life-saving
purposes. Other life-saving appliances include liferafts, lifebuoys
and individual lifejackets.
