BASIC INFORMATION
1.7 Units .1 General
1.8.1 Definitions of terms
1.8.1.1 The terms in Table 4.1.1 are used within these Rules to describe the items which their respective definitions describe.
Table 4.1.1 Definitions of Terms Terms Definition
Accommodation
deck A deck used primarily for the accommodation of the crew Accommodation
ladder
A portable set of steps on a ship’s side for people boarding from small boats or from a pier
Aft peak The area aft of the aft peak bulkhead
Aft peak bulkhead The first main transverse watertight bulkhead forward of the stern Aft peak tank The compartment in the narrow part of the stern aft of the aft peak
bulkhead
Anchor a device which is attached to anchor chain at one end and lowered into the sea bed to hold a ship in position; it is designed to grip the bottom when it is dragged by the ship trying to float away under the influence of wind and current; usually made of heavy casting or casting
Ballast tank A compartment used for the storage of water ballast
Bay The area between adjacent transverse frames or transverse bulkheads Bilge keel A piece of plate set perpendicular to a ship’s shell along the bilges to
reduce the rolling motion
Bilge plating The area of curved plating between the bottom shell and side shell. To be taken as follows: From the start of the curvature at the lower turn of bilge on the bottom to the lesser of, the end of curvature at the upper turn of the bilge on the side shell or 0.2D above the baseline/local centreline elevation
Bilge strake The lower strake of bilge plating
Boss The boss of propeller is the central part to which propeller blades are attached and through which the shaft end passes
Bottom shell The shell envelope plating forming the predominantly flat bottom portion of the shell envelope including the keel plate
Bow The structural arrangement and form of the forward end of the ship Bower Anchor An anchor carried at the bow of the ship
Bracket An extra structural component used to increase the strength of a joint between two structural members
Bracket toe The narrow end of a tapered bracket
Breakwater Inclined and stiffened plate structure on a weather deck to break and deflect the flow of water coming over the bow
Breast hook A triangular plate bracket joining port and starboard side structural members at the stem
Bridge An elevated superstructure having a clear view forward and at each side, and from which a ship is steered
Bulb profile A stiffener utilising an increase in steel mass on the outer end of the web instead of a separate flange
Bulkhead A structural partition wall sub-dividing the interior of the ship into compartments
Bulkhead deck The uppermost continuous deck to which transverse watertight bulkheads and shell are carried
Bulkhead stool The lower or upper base of a corrugated bulkhead
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Table 4.1.1 (Continued) Definitions of Terms Terms Definition
Bulkhead structure The transverse or longitudinal bulkhead plating with stiffeners and girders
Bulwark The vertical plating immediately above the upper edge of the ship’s side surrounding the exposed deck(s)
Bunker A compartment for the storage of fuel oil used by the ship's machinery Cable A rope or chain attached to the anchor
Camber The upward rise of the weather deck from both sides towards the centreline of the ship
Cargo tank
bulkhead A boundary bulkhead separating cargo tanks
Cargo area The part of the ship that contains cargo tanks and cargo/slop tanks and adjacent areas including ballast tanks, fuel tanks, cofferdams, void spaces and also including deck areas throughout the entire length and breadth of the part of the ship over the mentioned spaces. It includes the collision bulkhead and the transverse bulkhead at the aft end of the cargo block.
Carlings A stiffening member used to supplement the regular stiffening arrangement
Casing The covering or bulkhead around or about any space for protection Cellular
construction
A structural arrangement where there are two closely spaced boundaries and internal diaphragm plates arranged in such a manner to create small compartments
Centreline girder A longitudinal member located on the centreline of the ship
Chain Connected metal rings or links used for holding anchor, fastening timber cargoes, etc.
Chain locker A compartment usually at the forward end of a ship which is used to store the anchor chain
Chain pipe A section of pipe through which the anchor chain enters or leaves the chain locker
Chain stopper A device for securing the chain cable when riding at anchor as well as securing the anchor in the housed position in the hawse pipe, thereby relieving the strain on the windlass
Coaming The vertical boundary structure of a hatch or skylight
Cofferdams The spaces between two bulkheads or decks primarily designed as a safeguard against leakage of oil from one compartment to another Collar plate A patch used to, partly or completely, close a hole cut for a longitudinal
stiffener passing through a transverse web
Collision bulkhead The foremost main transverse watertight bulkhead
Companionway A weathertight entrance leading from a ship’s deck to spaces below Compartment An internal space bounded by bulkheads or plating
Confined space A space identified by one of the following characteristics: limited openings for entry and exit, unfavourable natural ventilation or not designed for continuous worker occupancy
Corrugated bulkhead
A bulkhead comprised of plating arranged in a corrugated fashion Cross ties Large transverse structural members joining longitudinal bulkheads and
used to support them against hydrostatic and hydrodynamic loads Deck A horizontal structure element that defines the upper or lower boundary
of a compartment
Deck house A decked structure other than a superstructure, located on the freeboard deck or above.
Deck structure The deck plating with stiffeners, girders and supporting pillars
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Table 4.1.1 (Continued) Definitions of Terms Terms Definition
Deep tank any tank which extends between two decks or the shell/inner bottom and the deck above or higher
Discharges Any piping leading through the ship’s sides for conveying bilge water, circulating water, drains etc.
Docking bracket A bracket located in the double bottom to locally strengthen the bottom structure for the purposes of docking
Double bottom structure
The shell plating with stiffeners below the top of the inner bottom and other elements below and including the inner bottom plating
Doubler Small piece of plate which is attached to a larger area of plate that requires strengthening in that location. Usually at the attachment point of a stiffener
Double skin member
Double skin member is defined as a structural member where the idealized beam comprises webs, with top and bottom flanges formed by attached plating
Duct keel A keel built of plates in box form extending the length of the cargo tank.
It is used to house ballast and other piping leading forward which otherwise would have to run through the cargo tanks
Enclosed
superstructure The superstructure with bulkheads forward and/or aft fitted with weather tight doors and closing appliances
Engine room bulkhead
A transverse bulkhead either directly forward or aft of the engine room Face plate The section of a stiffening member attached to the plate via a web and is
usually parallel to the plated surface
Flange The section of a stiffening member, typically attached to the web, but is sometimes formed by bending the web over. It is usually parallel to the plated surface
Flat bar A stiffener comprising only of a web Floor A bottom transverse member
Forecastle A short superstructure situated at the bow
Fore peak The area of the ship forward of the collision bulkhead Fore peak deck A short raised deck extending aft from the bow of the ship
Freeboard deck Generally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all exposed openings
Freeing port An opening in the bulwarks to allow water shipped on deck to run freely overboard
Gangway The raised walkway between superstructure, such as between the forecastle and bridge, or between the bridge and poop
Girder A collective term for primary supporting structural members
Gudgeon A block with a hole in the centre to receive the pintle of a rudder; located on the stern post, it supports and allows the rudder to swing
Gunwale The upper edge of the ship’s sides
Gusset A plate, usually fitted to distribute forces at a strength connection between two structural members
Hatch ways Openings, generally rectangular, in a ship’s deck affording access into the compartment below
Hawse pipe Steel pipe through which the hawser or cable of anchor passes, located in the ship's bow on either side of the stem, also known as spurling pipe Hawser Large steel wire or fibre rope used for towing or mooring
Hopper plating Plating running the length of a compartment sloping between the inner bottom and vertical portion of inner hull longitudinal bulkhead
HP Holland Profile
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Table 4.1.1 (Continued) Definitions of Terms Terms Definition
Independent tank A self supporting tank
Inner hull The innermost plating forming a second layer to the hull of the ship Intercostal Longitudinal member between the floors or frames of a ship; it is
non-continuous
JIS Japanese industrial standard profile
Keel The main structural member or backbone of a ship running longitudinal along centreline of bottom. Usually a flat plate stiffened by a vertical plate on its centreline inside the shell
Knuckle A discontinuity in a structural member
Lightening hole A hole cut in a structural member to reduce its weight
Limber hole A small drain hole cut in a frame or plate to prevent water or oil from collecting
Local support members
Local support members are defined as local stiffening members which only influence the structural integrity of a single panel, e.g. deck beams Longitudinal
centreline bulkhead
A longitudinal bulkhead located on the centreline of the ship
Longitudinal hull girder structural members
Structural members that contribute to the longitudinal strength of the hull girder, including: deck, side, bottom, inner bottom, inner hull longitudinal bulkheads including upper sloped plating where fitted, hopper, bilge plate, longitudinal bulkheads, double bottom girders and horizontal girders in wing ballast tanks
Longitudinal hull girder shear structural members
Structural members that contribute to strength against hull girder vertical shear loads, including: side, inner hull longitudinal bulkheads, hopper, longitudinal bulkheads and double bottom girders
Manhole A round or oval hole cut in decks, tanks, etc., for the purpose of providing access
Margin plate The outboard strake of the inner bottom and when turned down at the bilge the margin plate (or girder) forms the outer boundary of the double bottom
Notch A discontinuity in a structural member caused by welding Oil fuel tank A tank used for the storage of fuel oil
Pillar A vertical support placed between decks where the deck is unsupported by the shell or bulkhead
Pintle Vertical pin on a rudder’s forward edge that enables the rudder to hang onto the stern post and swing when it fits into the gudgeon
Pipe tunnel The void space running in the midships fore and aft lines between the inner bottom and shell plating forming a protective space for bilge, ballast and other lines extending from the engine room to the tanks Poop The space below an enclosed superstructure at the extreme aft end of a
ship
Poop deck The first deck above the shelter deck at the aft end of a ship Primary support
members
Members of the beam, girder or stringer type which ensure the overall structural integrity of the hull envelope and tank boundaries, e.g. double bottom floors and girders, transverse side structure, deck transverses, bulkhead stringers and vertical webs on longitudinal bulkheads
Rudder A device, usually of an aerofoil or flat section, that is used to steer a ship.
A common type has a vertical fin at the stern and is able to move from 35 degrees port to 35 degrees starboard; rudders are characterised by their area, aspect ratio, and shape
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Table 4.1.1 (Continued) Definitions of Terms Terms Definition
Scallop A hole cut into a stiffening member to allow continuous welding of a plate seam
Scarfing bracket A bracket used between two offset structural items Scantlings The physical dimensions of a structural item
Scupper Any opening for carrying off water from a deck, either directly or through piping
Scuttle A small opening in a deck or elsewhere, usually fitted with a cover or lid or a door for access to a compartment
Shedder plates Slanted plates that are fitted to minimise pocketing of residual cargo in way of corrugated bulkheads
Sheer strake The top strake of a ship’s side shell plating
Shelf plate A horizontal plate located on the top of a bulkhead stool Shell envelope
plating
The shell plating forming the effective hull girder
Side shell The shell envelope plating forming the sideportion of the shell envelope above the bilge plating
Single skin member
Single skin member is defined as a structural member where the idealized beam comprises a web, with a top flange formed by attached plating and a bottom flange formed by a face plate
Skylight A deck opening fitted with or without a glass port light and serving as a ventilator for engine room, quarters, etc.
Slop tank A tank in an oil tanker which is used to collect the oil and water mixtures from cargo tanks after tank washing
Spaces Separate compartments including tanks Stay Bulwark and hatch coaming brackets
Stem The piece of bar or plating at which a ship's outside plating terminates at forward end
Stern frame The heavy strength member in single or triple screw ships, combining the rudder post
Stern tube A tube through which the shaft passes to the propeller; and acts as an after bearings for the shafting and may be water or oil lubricated
Stiffener A collective term for secondary supporting structural members Stool A structure supporting tank bulkheads
Strake A course, or row, of shell, deck, bulkhead, or other plating Strength deck The uppermost continuous deck
Stringer Horizontal girders linking vertical web frames Stringer plate The outside strake of deck plating
Superstructure A decked structure on the freeboard deck, extending from side to side of the ship or with the side plating not being inboard of the shell plating more than 0.04B.
Tank top The horizontal plating forming the bottom of a cargo tank Towing pennant A long rope which is used to effect the tow of a ship
Transom The structural arrangement and form of the aft end of the ship
Transverse ring All transverse material appearing in a cross-section of the ship's hull, in way of a double bottom floor, vertical web and deck transverse girder Transverse web
frame The primary transverse girders which join the ships longitudinal structure Tripping bracket A bracket used to strengthen a structural member under compression,
against torsional forces
‘Tween deck An abbreviation of between decks, placed between the upper deck and the tank top in the cargo tanks
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Table 4.1.1 (Continued) Definitions of Terms Terms Definition
Ullage The quantity represented by the unoccupied space in a tank Void An enclosed empty space in a ship
Wash bulkhead A perforated or partial bulkhead in a tank
Watertight Watertight means capable of preventing the passage of water through the structure under a head of water for which the surrounding structure is designed
Weather deck A deck or section of deck exposed to the elements which has means of closing weathertight, all hatches and openings
Weathertight Weathertight means that in any sea conditions water will not penetrate into the ship
Web The section of a stiffening member attached perpendicular to the plated surface
Wind and water strakes
The strakes of a ship's side shell plating between the ballast and the deepest load waterline
Windlass A machine for lifting and lowering the anchor chain
Wing tank The space bounded by the inner hull longitudinal bulkhead and side shell RCN 2 to July 2008 version (effective from 1 July 2010)
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