Aframax (tanker)
An AFRA (Average Freight Rate Assessment)max is a medium-sized oil tanker which ranges in size between 80,000 and 119,999 deadweight tonnes. Aframax tankers have an average cargo carrying capacity of 750,000 barrels.
Anchor Holding Power
The holding power of an anchor is normally defined as the ratio of the actual pull it can withstand without dragging to the weight of the anchor in air.
Anchor Lashing
A device for holding the anchor tight in its housed position.
Axial Compression Fatigue
The tendency of a fibre to fail when it is subjected to cyclic loading which exerts compression along its axis.
Band Brake
A brake type where frictional force is applied by increasing the tension in a flexible band around the drum.
Bitter End
The inboard end of a chain, rope or cable that is secured onboard.
Bolster
A protrusion on the hull, at the lower end of the hawse pipe, to permit safe stowage of the anchor flukes and also to facilitate lowering of the anchor clear of the hull form.
Bottlescrew
A metal sleeve with opposite internal threads at each end for the threaded ends of two rods or ring bolts, forming a coupling that can be turned to tighten or loosen the rods or wires attached to the ringbolts. Also known as a ‘turnbuckle’.
Bower Anchor
Each of the two main anchors of a ship carried permanently attached to their cables on each side of the bow and always ready to be let go.
Breaking Load
The force which, when steadily applied to a structural member or material is just sufficient to break or rupture it.
Cable Lifter
A deeply grooved drum shaped to engage the links of a chain cable. Also termed ‘Gypsy’.
Calliper
A hydraulically activated device in a disc brake system which is mounted straddling the brake disc. The calliper contains at least one piston and two brake pads. Hydraulic pressure on the pistons forces the pads against the disc.
Catenary
The curve made by an anchor chain cable between the hawse pipe and the seabed.
Chain Locker
A compartment for storage of the chain cable.
Chain Stopper
A device secured to the ship’s structure separate from the cable lifter for the purpose of securing a chain cable.
Charpy V Test
A pendulum-type single-blow impact test in which the specimen, usually notched, is supported at both ends as a simple beam and broken by a falling pendulum. The energy absorbed, as determined by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness.
Compressor Stopper
A type of chain stopper in which the chain is held in position by compressive forces applied on both sides of the chain.
Devil’s Claw
A component of a type of anchor lashing in which one or more hook-shaped claws engage the anchor chain.
Disc Brake
A hydraulic brake in which friction is applied to both sides of a rotating disk by brake pads actuated callipers.
Equipment Number
A number derived as a function of vessel size that is used to determine Classification Society anchoring system requirements.
Gauge Length
The distance between the tip of the anchor fluke and the extended centreline of the anchor shackle pin with flukes at their maximum deployed angle.
Guillotine Bar
A component of a chain stopper comprising of a locking bar and securing arrangement to hold the cable in the stopper.
Gypsy
A deeply grooved drum shaped to engage the links of a chain cable. Also termed ‘Cable Lifter’
Hawse Pipe
A tube passing from the deck to the outer shell of the ship through which the chain cable passes.
IACS
International Association of Classification Societies.
Kenter Shackle
A type of connecting link used to connect two lengths of chain cable where the terminations of the two lengths have the same dimensions. The connecting link has the same outside length as a chain link of the same diameter.
Load Cell
An electronic device (transducer) that is used to convert a force into an electrical signal.
MR (tanker)
A Medium Range tanker of a size that is typically between 25,000 and 50,000 tonnes deadweight.
Proof Load
A predetermined test load, greater than the service load, to which a specimen is subjected before acceptance.
Safety Factor
A margin over MBL to allow for uncertainties.
Scope (of cable)
The ratio of the length of cable, from hawse pipe to the anchor ‘D’ shackle, to the depth of water from hawse pipe to seabed.
Shackle (of cable)
A standard length of chain that is equal to 15 fathoms or 27.5 metres. Also termed a ‘shot:
Spurling Pipe
A tube passing from the deck to the chain locker through which the chain cable passes.
Stocked Anchor
An obsolete type of anchor in which a stock was arranged at right angles to the shank and flukes to prevent the anchor rotating on the seabed.
Stripper Bar
A device that separates the chain from the cable lifter to guide the links into the spurling pipe.
Suezmax
Suezmaxes are medium-sized oil tankers that are slightly larger than Aframaxes, ranging in size between 120,000 and 199,999 deadweight tonnes, with an average cargo carrying capacity of 1.0 million barrels and are named for their status as the largest size oil tanker able to travel fully laden through the Suez Canal.
SWL Safe Working Load
Generally, a load less than the breaking load by a safety factor defined by a code, standard or good engineering practice.
Total Chain Length
The minimum total length of the chain cable for the two bower anchors, according to the rules of the Classification Societies.
Ultra Large Crude Carrier (ULCC)
Tankers able to transport up to 3 million barrels of oil as cargo, typically above 320,000 tonnes deadweight.
UTS
Ultimate tensile strength.
Very Large Crude Carrier (VLCC)
Tankers able to transport up to 2 million barrels of oil as cargo, typically of between 200,000 and 320,000 tonnes deadweight.
Warping End
A part similar to a drum but longitudinally concave shaped and fixed to the winch shaft end for hauling, but not storing, a rope.
Whelps
Protrusions on the inside of the flanges of the cable lifter that are shaped and sized to follow the path of the anchor chain as it enters and leaves the cable lifter.
Windlass
A machine designed to lower and hoist the anchor. It has one or more cable lifters mounted on a horizontal shaft, each fitted with a brake. The cable lifters are capable of being de-clutched from the prime mover. One or two warping ends may also be fitted.