1
The Ship
Introduction
The art and science of seamanship has developed from the experience of maritime nations over many centuries. Sea transport has moved through the changing years of propulsion by oars, the discovery days of sail, through the advances of steam and the benefits of oil to finally emerge into atomic power. The marine industry has historically seen the excitement of discovering new worlds and the conquering of offshore boundaries, to become settled with the advance of trade in all directions of the compass.
The ship, once stored and provisioned, becomes the ideal in self-sufficiency, capable of the transport of cargo, livestock, troops, passengers, gas, fluids, minerals, etc. The fact that the vessel provides a source of power which can cope with varying degrees of emergency and still be able to sustain itself, says a lot for the developed marine industry.
The ship is equipped with such ancillary equipment as required to be able to load and discharge, in a safe condition, all cargoes and passengers as the vessel is designed to accommodate. Bearing in mind the function of the ship, it is not difficult for seafarers to realize how their characters have been influenced by the independent nature of their employment. Seamanship and the ships themselves have created the spirit of adventure that turned such men as Magellan, Drake and Nelson into more than legends.
Even in todayâs ships, be they of the mercantile marine or âmen of warâ, it is hoped that the same spirit prevails alongside past practice and the increased levels of technology.
Terms and Definitions
Abeam
A bearing projected at right angles from the fore and aft line, outwards from the widest part of the ship (Figure 1.1).
Figure 1.1 The ship in relation to its surroundings.
Ahead
âRight aheadâ is the line that the fore and aft line, if projected, would extend in front of the vessel (Figure 1.1). Opposite to the term âasternâ when used in relation to relative bearings. It may also be used as an engine-room order to cause the engines to turn in order to move the ship ahead.
Amidships
The middle of the vessel in both transverse and longitudinal directions. More commonly used as a helm order, where it is usually shortened to âmidshipsâ (see Table 10.1).
Athwartships
Defined as âin a directionâ from one side of the ship to the other, at a right angle to the fore and aft line.
Breadth
The maximum beam of the vessel measured from the outside edge of the shell plating on either side of the vessel is the extreme breadth (Figure 1.2).
The beam of the vessel measured amidships, between the inside edge of the shell plating on either side of the vessel, is the moulded breadth (Figure 1.2).
Camber (or round of beam)
The curvature of the deck in the athwartships direction. The measurement is made by comparing the height of the deck at the centre of the vessel to the height of the deck at the side of the vessel (Figure 1.2).
Depth
The extreme depth of the vessel is measured from the bottom side of the keel to the top of the deck beams, the measurement being taken at the side of the vessel.
Figure 1.2 Shipâs principal dimensions.
The moulded depth is measured from the top side of the keel to the top of the deck beams, at the side of the vessel.
Flare
The outward curvature of the shell plating in the foremost part of the vessel, providing more width to the forecastle head and at the same time helping to prevent water coming aboard.
Fore and Aft Line
An imaginary line passing from the stem to the stern through the centre of the vessel (Figure 1.3).
Figure 1.3 The ship in section and plan.
Freeboard
This is the vertical distance, measured at the shipâs side, from the waterline to the top of the freeboard deck edge. The freeboard measurement is taken at the amidships point. The deck edge is marked by a painted line 25 mm Ă 300 mm, above the Plimsoll line (Figure 1.2 and Figure 1.36).
Keel Rake
The angle of inclination of the line of the keel to the horizontal (Figure 1.4).
Length between Perpendiculars (LBP)
The distance between the forward and aft perpendicu...
