Extended Operational and Trade Vocabulary

Mooring, Anchoring, OCIMF MEG4, and Equipment Numeral glossary

Vocabulary of mooring and anchoring under OCIMF MEG4: high-holding-power AC-14 and Admiralty-pattern anchors, stud-link anchor chain measured in shots, anchor buoys and crowns, the IACS equipment numeral sizing anchors and chain, and the line-management, fitting and seabed-holding terminology of ship-mooring and anchoring practice.

269 defined terms.

Showing 250 on this page (page 1 of 2).

A

AC-14 Anchor: High-holding-power stockless anchor of the AC-14 pattern accepted by IACS UR A1 with a holding-power factor approximately twice that of an ordinary stockless anchor.
Admiralty Pattern Anchor: Traditional stocked anchor with a transverse stock at the crown that forces a fluke to bite, largely superseded on commercial ships but retained on small craft and as kedges.
Anchor: Heavy device dropped on a cable to hold the ship to the seabed.
Anchor buoy: Small buoy attached by a tripping line to mark the anchor's position.
Anchor chain: Stud-link chain used between anchor and ship.
Anchor Crown: Lowermost part of an anchor where the shank meets the arms and where the tripping ring or anchor buoy is attached.
Anchor Handling Tug Supply Vessel (AHTS): Offshore vessel fitted with a stern roller, large winches, and shark jaws for deploying and retrieving anchors of mobile offshore units.
Anchor pocket: Recess in the hull plating to house the anchor flukes when stowed.
Anchor Shackle: End connector that secures the chain to the anchor crown, traditionally a D-shape with a forelock pin.
Anchor Stock: Transverse bar on traditional stocked anchors that orients the flukes to bite the seabed.
Anchor Swivel: Rotatable link inserted near the anchor or in the chain to relieve twist when the vessel swings around its anchor.
Anchor watch: Watch maintained on anchored vessel.
Anchor Windlass: Deck machinery for raising and lowering the ship's anchor and chain cable, supplied by makers such as MacGregor Pusnes, IHC Hytop, and Rolls-Royce.
Anchorage: water area where vessels can safely anchor while awaiting berth.
AQWA: Hydrodynamic and mooring analysis suite from ANSYS used for diffraction-radiation, time-domain coupled mooring, and station-keeping studies.
Arch Fender: Elastomeric fender of arched cross-section bolted to a quay face that deflects under load to absorb berthing energy.
ASTM F1145: ASTM standard for cast or fabricated bollards used aboard ships, covering geometry, loading, and welding for bitts and cruciform bollards.
Awning Deck Fairlead: Fairlead positioned at upper deck level to redirect mooring lines from below to a shoreside hook or bollard.

B

Ballast condition: Loading condition with no cargo, only ballast water and consumables.
Beam (B): Maximum breadth of the hull.
Becket: Small loop or eye of rope.
Bekaert Bezinal: Zinc-aluminium coating used by Bekaert on steel wire rope cores to improve corrosion resistance over plain galvanizing.
Bend (Knot): Knot used to join two ropes, such as the carrick bend or sheet bend used in seamanship for joining hawsers of unequal size.
Berthing Energy: Kinetic energy of an approaching ship to be absorbed by fenders, computed in PIANC 2002 WG33 from displacement, approach velocity, and coefficients for eccentricity, virtual mass, softness, and…
Berthing Performance: Combined characterisation of fender energy absorption, reaction force, and hull pressure under design berthing velocity.
Bitt: Vertical post on deck for securing lines.
Bitt Pin: Removable horizontal pin between the heads of a double bitt that prevents a turned line from jumping clear.
Bitter end: Inboard end of the anchor cable.
Bollard: Mooring fitting on quay or dolphin.
Bollard Pull (BP): Static pulling force a tug can exert on a stationary load, measured in tonnes.
Boss-back Anchor: Pool TW-type anchor whose enlarged tripping palms ensure rapid fluke engagement on hard seabeds.
Bow Anchor: Anchor stowed in the bow hawse pipe, normally the main working anchor on merchant ships.
Bow Patent Anchor: Stockless anchor of the Bow patent design, an older HHP pattern still seen on legacy tonnage.
Braided Rope: Rope construction in which strands are interwoven in plaits, common in modern HMPE mooring tails and double-braid polyester.
Brake (Windlass): Band or disc brake on the windlass gypsy that holds the chain when the prime mover is disengaged.
Brake Holding Capacity: Rated load that a windlass brake can hold without slipping, normally tested to a fraction of chain breaking load per class rule.
Breast line: Mooring line led at right angles to the keel to hold the ship against the berth.
Bridgestone Super Cone: Bridgestone-manufactured rubber cone fender developed for large vessels at modern berths.
Bridon-Bekaert Ropes Group: Belgian-British producer of steel-wire ropes and synthetic mooring lines, including Diamond and Viking ranges.
Bruce Anchor: Single-piece cast SHHP (super-high-holding-power) anchor developed by Bruce Anchor Group for offshore and merchant use.
Bulwark Fairlead: Fairlead built into the bulwark plating to lead a mooring line outboard with controlled fleet angle.

C

Cable: Unit of length of one-tenth of a nautical mile, 185.2 m.
Cable Lifter: Synonym for gypsy or wildcat, the toothed wheel on a windlass that engages the studs of anchor chain.
Cable Stopper: Device that locks the anchor cable when the windlass is disengaged, taking the load off the brake.
Capstan: Vertical-axis rotating drum used for heaving on ropes or cable.
Carpenter Stopper: Wedge-type stopper that grips a wire rope without damage and is used for stopping off mooring wires.
Cast Bollard: Bollard manufactured by casting in steel or ductile iron rather than fabricated from welded plate.
Catenary: sag of a mooring line or shore-power cable between supports.
Cell Fender: Cylindrical rubber fender comprising an inner cell core and front frame used on tug bows and harbor structures.
Centre Lead: Fairlead located on the ship's centreline at the bow or stern, often a closed Panama chock on ocean-going ships.
Chain Compressor: Hinged dog that drops over the chain immediately forward of the windlass to hold it under load.
Chain Diameter: Nominal bar diameter of a chain link, the principal parameter governing chain grade and breaking load tables.
Chain Hawse: Combined term for the hawse pipe and adjacent fittings through which the anchor chain leads.
Chain locker: Compartment for stowing anchor chain.
Chain Pipe: See Spurling Pipe; the trunk leading from the windlass deck down into the chain locker.
Chain Shot: Standard length of anchor cable, 15 fathoms (27.5 m) in IACS practice, joined by Kenter or similar shackles.
Chain stopper: Device that holds the anchor chain when the windlass is disengaged.
Chinese Pen: Compartmental division within a chain locker that helps anchor chain self-stow in tiers and prevents shifting.
Chock: Mooring fitting that guides a line outboard.
Cleat: Two-horned fitting around which a line is belayed.
Closed Chock: Chock that fully encloses the rope opening to prevent the line jumping out under shock loading, mandatory at some lead positions per IACS UR A2.
Cofibrex: Hybrid mooring line construction combining steel wire with a synthetic jacket to gain abrasion resistance.
Common Link: Standard stud or studless link making up the bulk of an anchor cable shot, as distinct from enlarged or end links.
Cone Fender: Conical rubber fender used on tug bows and ship-side contact areas.
Constant Tension Winch: Mooring winch fitted with control system that pays out or hauls in line to maintain a preset tension as the ship moves at the berth.
COSMOS: Russian-built LEO satellites that historically hosted the Cospas payload.
Crown (Anchor): Junction of shank and arms in an anchor, forming the bearing surface against the seabed when stowed.
Crown Plate: Cast or forged element forming the crown of an anchor, especially in stockless designs.
Crown Shackle: Shackle securing the chain to the crown of certain anchor designs.
Cruciform Bollard: ASTM F1145 cruciform-shape bollard with four arms, providing multiple lead directions for mooring lines.
Cylindrical Fender: Solid rubber fender of cylindrical cross-section, normally rope-suspended along a quay face.

D

D-Shackle: Shackle whose bow forms a D, used widely as joining and anchor shackles.
Delta Anchor: One-piece plough-type HHP anchor of triangular shape developed by Vryhof for merchant and small craft use.
Devil's Claw: Two-prong chain stopper with hinged claw that locks over a stud link to secure the anchor when stowed at sea.
Displacement (Delta): Mass or volume of water displaced by a ship; in the IACS UR A1 formula, the moulded displacement at summer load draft in cubic metres.
Dog (Stopper): Hinged claw on a chain stopper that drops over a link to hold the chain.
Double Bitt: Two parallel vertical bitts on a common base around which a line is figured-of-eight, the standard mooring fitting on merchant ships.
Double Drum Winch: Towing winch with two independently controlled drums permitting simultaneous bow and stern operations.
Drag (anchor): Failure of an anchor to hold, allowing the vessel to move.
Drogue: Sea anchor or speed-reducing device streamed astern.
Drum End: Smooth tapered end of a windlass shaft used for warping, also called a warping head or gypsy head.
Dynamic Positioning (DP): Computer-controlled station-keeping via thrusters.
Dyneema: High-modulus polyethylene running rigging line common in racing yachts.

E

Eccentricity Coefficient (Ce): PIANC 2002 WG33 factor in the berthing energy formula accounting for the ship rotating about the contact point.
Effective Height (h): Vertical distance from the summer load waterline to the top of the uppermost continuous house in the IACS UR A1 equipment number formula.
EN (Equipment Number): Numerical index calculated per IACS UR A1 used to enter the equipment table and obtain required anchor mass, chain length and diameter, and hawser strength.
End Link: Link at the end of a chain shot, larger than a common link and made without a stud to suit the joining shackle.
Energy Absorption (EA): Energy in kNm a fender deflects through during compression, the principal selection criterion under PIANC 2002 WG33.
English Braids: UK manufacturer of synthetic mooring and rigging ropes.
Enlarged Link: Link of greater diameter than common links placed at the ends of a shot to accommodate a Kenter or D shackle.
Equipment Number Formula: IACS UR A1 expression EN = Delta^(2/3) + 2(hB + sum A) with Delta in m^3, h and B in m, and side projected area A in m^2.
Equipment Table: Table within IACS UR A1 giving, for each range of equipment number, the number and mass of anchors, total chain length and grade-dependent diameter, and mooring/towing line characteristics.

F

Fairlead: Fitting that leads a rope in the desired direction without chafe.
Fairlead Universal: Multi-roller fairlead permitting almost any lead angle with low friction, common at the ship side abreast of mooring winches.
Fender: Energy absorbing system at berth, designed per PIANC WG211 (formerly WG33).
Fibre Rope Core (FRC): Core of a wire rope made of natural or synthetic fibre that cushions the strands; less robust than an IWRC and rarely used on modern moorings.
Figure of Eight: Standard method of laying a line on a bitt or cleat in alternating turns to develop friction.
Flake (Line): Lay out a mooring line in long flat coils on deck so that it runs free without kinks when paid out.
Flipper Delta Anchor: Vryhof-developed Flipper Delta anchor incorporating side flippers to ensure positive fluke engagement for permanent moorings.
Fluke: Pointed arm of an anchor that digs in.
Foam-Filled Fender: Pneumatic-style fender filled with closed-cell polyethylene foam and skinned with reinforced elastomer, used for ship-to-ship transfers.
Forelock Pin: Tapered pin secured by a transverse cotter formerly used on anchor and chain shackles before the modern Kenter design.
Frictional Holding: Component of mooring restraint contributed by a length of chain lying along the seabed.

G

Gob Eye: Hard point on the after deck through which the gob rope is led.
Gob Rope: Restraint line that holds the towline down toward the stern of a conventional tug to prevent girting.
Grade 2 Chain: Lower-strength grade of stud-link anchor chain (Grade U2) permitted by class for anchor service on smaller equipment numbers.
Grade 3 Chain: Common grade of stud-link anchor chain (Grade U3) used on most merchant vessels, with higher strength than Grade 2.
Grade R3 / R4 / R5 Chain: ORQ-derived high-strength chain grades used for permanent and mobile offshore moorings with progressively higher tensile properties.
Grapnel: Small anchor with four or more flukes.
Grommet Strop: Endless loop made by laying up a single strand of rope into a multi-stranded ring, used as a soft eye on mooring tails.
Gypsy: Notched wheel on a windlass that grips the anchor chain.

H

Hall Anchor: Original stockless anchor pattern designed by William Hall, the archetype against which holding-power factors of HHP anchors are compared.
Hand Brake: Manually operated band brake on the windlass gypsy used for controlling chain veer and for emergency holding.
Hawse pipe: Pipe through which the anchor cable passes.
Hawser: Heavy rope or cable for mooring or towing.
HHP Anchor: High-holding-power anchor that develops at least twice the holding power of an equivalent ordinary stockless anchor when tested per IACS UR A1.
HMPE: High-modulus polyethylene fiber such as Dyneema or Spectra used in mooring lines.
Holding Power: Maximum horizontal force an anchor can resist in a defined seabed before dragging, normally expressed as a multiple of anchor weight.
Hook (QRH): Steel hook in a Quick Release Hook battery that holds a mooring eye and can be released hydraulically or manually under load.
Hull Pressure (HP): Pressure imposed on the ship's shell by a fender's reaction force divided by contact area, typically limited to 200 to 250 kN/m^2 for VLCCs and similar.
Hybrid Composite Line: Mooring line combining materials such as polyester jackets over HMPE cores to balance cost, weight, and durability.
Hydraulic Windlass: Anchor windlass driven by a hydraulic motor, valued for fine speed control and stall tolerance.

I

IACS UR A1: Unified Requirement of the International Association of Classification Societies prescribing the equipment number, anchors, chain, and tow/mooring lines for ships.
IACS UR A2: Unified Requirement specifying shipboard fittings and supporting hull structures associated with towing and mooring on conventional ships.
iDock: Mampaey shore-side automated mooring concept using vacuum or magnetic pads to moor vessels without lines.
IMO Resolution A.535: IMO recommendation on emergency towing requirements which informs the design of emergency towing arrangements alongside IACS UR.
Inboard End: Bitter end of the anchor cable secured inside the chain locker.
Independent Wire Rope Core (IWRC): Steel wire rope core inside a larger wire rope giving higher strength and crush resistance than a fibre core, dominant in modern wire moorings.
Inhaul Line: Secondary line used to pull a heavy mooring eye onto a shore hook or bollard.
IP65 Rating: Ingress protection rating signifying dust-tight and water-jet-resistant enclosure, typical for windlass control panels exposed to the deck environment.
ISO 17357: International standard for floating pneumatic fenders of the Yokohama type, defining grades and test methods.
ISO 7825: International standard covering anchor windlass design and testing.

J

JIS A Type Pneumatic Fender: Japanese Industrial Standard pneumatic fender rated at lower initial internal pressure (50 kPa) for moderate energy duty.
JIS B Type Pneumatic Fender: Higher-pressure (80 kPa) pneumatic fender giving greater energy absorption for large tankers and bulk carriers.
Joining shackle: Detachable link uniting lengths of anchor chain.

K

Kedge Anchor: Smaller secondary anchor carried for warping the ship off a grounding or to hold the stern in tide.
Kenter shackle: Patent connecting link replacing a length of chain.
Kevlar: An aramid fiber used in racing sails and rigging for strength and low stretch.
KTL Mooring: Korean manufacturer of mooring quick release hook batteries and associated load monitoring equipment.

L

Lankhorst Ropes: Dutch rope manufacturer in Sneek producing MoorLine HMPE and polyester mooring ropes.
Lankoforce: Lankhorst trade name for HMPE mooring line products targeting tanker and gas carrier moorings.
Lay (Rope): Direction and pitch of the twist of strands in a rope, normally right-hand regular lay for general service ropes.
LDBF (Line Design Break Force): OCIMF MEG4 term for the certified MBL of the line used in design, with allowances for splices and tails.
Lifting Capacity (Windlass): Continuous duty pull required of an anchor windlass, traditionally specified as not less than the combined weight of one anchor and a defined length of chain in air at a given speed.
Line-throwing apparatus: Required by SOLAS III/18, capable of throwing a line at least 230 m with reasonable accuracy.
Linkage: Geometry of a swivel-and-pin assembly used between anchor and chain to allow free rotation.
Locker Sounding Pipe: Pipe used to measure water accumulation in the chain locker so that bilge alarms can be calibrated.

M

MacGregor QRH: Quick Release Hook product line manufactured by MacGregor for marine terminal mooring systems.
Mampaey iDock: Automated mooring system by Mampaey using ship-side vacuum pads on a shore arm to replace conventional lines.
Mampaey MoorMate: Mampaey-designed quick release hook with integrated load monitoring.
Marine Bumper: Generic term for elastomeric protection units on ships' sides or small craft, distinct from terminal-grade fenders.
Marlow Ropes: UK manufacturer of high performance synthetic mooring and rigging ropes.
Maximum Static Load (MSL): Per OCIMF MEG4, the maximum tension permitted in a mooring line under steady environmental loads, set at 50% of LDBF.
MBL (Minimum Breaking Load): Certified minimum breaking strength of a rope, wire, or chain as supplied.
MEG3: OCIMF Mooring Equipment Guidelines, 3rd Edition (2008), now superseded by MEG4.
MEG4: OCIMF Mooring Equipment Guidelines, referenced for SOLAS II-1/3-8.
MEG4 Addendum: 2020 supplement to MEG4 introducing clarifications on tails, mixed mooring systems, and human factors.
MEL (Mooring Equipment List): MEG4 document for each ship listing every mooring line, tail, shackle, hook, and fairlead with its certified properties.
Method 1 (Fender Selection): PIANC 2002 WG33 deterministic approach using design ship parameters and factors to size fenders.
Method 2 (Fender Selection): PIANC 2002 WG33 probabilistic approach using statistical distributions of berthing parameters.
MIMOSA: Mooring analysis software historically used in the Norwegian offshore sector for coupled vessel and line dynamics.
Mooring Bitts: Bollards or bitts arranged on the main deck for securing shore mooring lines.
Mooring boat: launch handling lines to buoys or dolphins.
Mooring Line: Generic term for any rope or wire used to secure a vessel to a berth, buoy, or another vessel.
Mooring Pattern: Layout of head, breast, spring, and stern lines selected to balance loads from wind, current, and waves.
Mooring System Management Plan (MSMP): The MEG4-mandated documented plan verified during SIRE 2.0 mooring chapter checks.
Mooring tail: synthetic tail at the end of high-modulus mooring lines.
Mushroom Anchor: Inverted-mushroom-shape anchor used for permanent moorings of light vessels and buoys where soft sediment provides suction grip.

N

Nominal Diameter: Quoted bar or rope diameter used in selection tables, distinct from measured circumference or actual breaking load.
Nylon (Polyamide): Synthetic fibre with high strength and elongation used in shock-absorbing mooring lines but losing strength when wet by about 10 to 15%.

O

OCIMF: Oil Companies International Marine Forum, owner of SIRE.
Open Chock: Chock that does not enclose the rope opening, simpler than a closed chock but unsuited to high snatch loads.
Optimoor: Mooring analysis software developed by Tension Technology International for static and quasi-dynamic ship-at-berth analysis.
Orcaflex: Time-domain dynamic-analysis code for offshore systems.
ORQ Chain: Oil Rig Quality stud-link chain originally developed for offshore drilling rig moorings, predecessor of the R3 to R5 grades.

P

Palm (Anchor): Flat working face of an anchor fluke that contacts and pushes against the seabed.
Panama chock: Closed mooring chock with a smooth oval lead.
Parallel Motion Fender (PMF): Fender system whose front face moves in a parallel motion as the ship contacts it, distributing reaction evenly along the hull.
Pelican hook: Hinged hook released by a sliding link.
Pendant (Anchor): Wire or chain attached to the anchor crown used to recover an offshore anchor for relocation.
PES (Polyester): Synthetic fibre with low elongation, low creep, and good UV resistance used widely in modern moorings, including double-braid construction.
PIANC 2002 WG33: PIANC report Guidelines for the Design of Fender Systems 2002 produced by Working Group 33 of MarCom, the basis for modern fender sizing.
Plasma: Cortland-trademarked HMPE rope with proprietary surface treatment for improved abrasion resistance.
Plough Anchor: Generic class of anchor including the CQR and Delta whose single fluke ploughs into the seabed.
Pneumatic Fender: Air-filled rubber fender, typically Yokohama-style, deployed between assisted vessel and quay.
Polyamide (PA): Same as Nylon; used for mooring tails where elastic energy absorption is required.
Polyester (PES): See PES.
Polypropylene (PP): Low-cost low-density synthetic fibre that floats; used as messenger lines and on small craft, not on tanker main moorings.
Pool TW Anchor: TW (twin-fluke) high-holding-power stockless anchor manufactured by Pool, accepted by class as HHP.
Power Stowage: Use of the windlass to pull the anchor fully home into the hawse pipe and pre-load the chain stopper.
Pre-tension Mooring Analysis: Static analysis ensuring that pretensioned lines balance and remain within allowable loads under design conditions.
Pretension: Tension applied to a mooring line at the start of operations to take up slack before environmental loads arrive.

Q

Quad Hook QRH: Quick Release Hook assembly with four hooks for very large mooring loads at deepwater berths.
Quick Release Hook (QRH): Mooring hook designed to release under load by a single lever or remote signal, available in 100 to 300-tonne ratings.

R

R3 / R3S / R4 / R4S / R5 Chain: Successive high-strength chain grades defined for offshore mooring, with R5 being the highest standard mass-produced grade.
Reaction Force (RF): Force in kN exerted by a fender back on the ship and quay at design deflection, the principal structural input for berth design.
Reverse Lay: Rope construction where the strands and the yarns within them are twisted in opposite directions to balance torque.
Riding Cable: Anchor cable taking the entire load on a single anchor at any one time.
Roller chock: Mooring chock with rollers.
Rope Stopper: Short line used to hold a mooring rope while transferring it from the winch drum to a bitt.
Rope Tail: See Mooring Tail.

S

Samson Rope: US manufacturer of synthetic mooring lines including Saturn-12 and AmSteel-Blue Dyneema ropes.
SCN Cone Fender: Sumitomo SCN cone fender, a widely specified high-performance cone fender for container and tanker berths.
SDF Fender: ShibataFenderTeam-designed cone fender of the SDF series, geometrically similar to legacy Sumitomo SCN designs.
SDMBL (Ship Design MBL): OCIMF MEG4 term for the line strength on which a tanker's mooring fittings are sized, separate from the actual LDBF of installed ropes.
Sea anchor: Conical drogue streamed to hold a vessel head to sea.
Shackle (Chain): Old measure equal to one shot of chain, typically 15 fathoms (27.5 m).
Shank: Long arm of an anchor between ring and crown.
ShibataFenderTeam: German fender manufacturer producing cell, cone, super arch, and pneumatic fenders.
Ship to Ship Transfer (STS): Cargo transfer between two vessels moored together, typically separated by Yokohama-type pneumatic fenders.
Shore Tension System: Active line tensioner mounted on the quay that maintains constant pull on a passive mooring line.
Shot of Chain: Standard length of anchor cable, IACS-aligned at 15 fathoms or 27.5 m, joined by Kenter shackles.
Single Bitt: Single vertical post used for securing lines, generally on smaller craft and as auxiliary mooring fitting.
Single Drum Winch: Mooring winch with one drum, often combined with a warping head on the same shaft.
SMS (Surge Management System): MEG4-recognised system for managing passing-vessel surge at exposed berths via active tension control or shore tensioners.
SOLAS II-1/3-8: SOLAS regulation requiring towing and mooring equipment to be of sufficient strength and arranged to allow safe operation, referencing IACS UR A2 in practice.
Spectra: Honeywell trademark for HMPE fibre used in mooring and rigging ropes.
Spek Anchor: Spek-pattern stockless anchor of Dutch design, accepted by class as a standard stockless type.
Spring Line: Mooring line led fore-and-aft and crossing the breast lines to restrain longitudinal motion at the berth.
Spurling Pipe: Vertical pipe leading anchor chain from the windlass deck down into the chain locker.
Stainless Wire Mooring: Wire mooring made of stainless rather than galvanized steel, used in special service such as offshore loading hawsers.
Standing part: Fixed part of a rope as opposed to the hauling part.
Stay Line: Mooring line tensioned longitudinally to oppose a particular environmental load, especially in single point moorings.
Steel Wire Mooring: Steel wire rope mooring component used in combination with chain in catenary and taut-leg systems.
Stevin Mk5 / Mk6: Vryhof drag-embedment anchors of conventional shape used widely for mobile offshore mooring.
Stevpris Mk5 / Mk6: Vryhof high-efficiency drag anchors with fixed-fluke geometry preferred for permanent and semi-permanent moorings.
Stockless anchor: Anchor without a stock, common modern type.
Stopper Line: Short heavy line used to transfer load from a winch drum to a bitt during handover of a mooring rope.
Strop: Loop of rope or wire.
Stud (Chain): Transverse bar in a stud-link chain providing stiffness and stable stowage.
Stud-Link Chain: Anchor chain whose links have a transverse stud welded or cast across each link to prevent kinking, the standard form for merchant ship anchor cables.
Submerged Turret Loading: Permanent mooring system whose turret connects below the waterline to a tanker's bow, common in North Sea fields.
Sumitomo SCN: Sumitomo Rubber Industries cone fender SCN series, an industry benchmark for cone fender performance.
Super Cone Fender: Cone-shaped rubber fender with axial deflection used at general cargo and container berths.
Super High Holding Power (SHHP): Anchor classification for designs whose holding power factor is at least four times that of an ordinary stockless anchor, accepted by class for reduced mass.
Swivel Piece: Short forged unit installed between anchor and chain, or in the chain, to permit relative rotation and prevent kinking.

T

Tail (Mooring): Synthetic rope tail spliced to the outboard end of a wire mooring to reduce snatch loads at the bollard.
Tension Technology International (TTI): UK consultancy developer of Optimoor mooring analysis software and rope-testing services.
Three-strand Rope: Classical rope construction with three twisted strands, used for general seamanship and lighter lines.
Tie-Off: Securing a line on a bitt or cleat with figure-of-eight turns and locking turns.
Topping lift: Rope supporting the outboard end of a boom or derrick.
Tow Line: Heavy rope or wire used to tow a vessel, distinct from mooring lines in design and certification.
Trelleborg: Swedish Baltic port hosting Stena Line, TT-Line, and Finnlines services to Travemunde, Rostock, Sassnitz, and Swinoujscie.
Trelleborg SmartHook: Trelleborg quick release mooring hook with integrated load monitoring and remote release.
Trelleborg Super M: Trelleborg cone fender series used at container and tanker berths.
Triple Hook QRH: Quick release hook assembly with three hooks for high mooring loads.
Tripping Palm: Projection on the crown of a stockless anchor that rotates the flukes downward when the anchor is laid on the seabed.
Tug Bollard Pull (TBP): Static thrust force available at a tug's towing point, certified by class.
Twist (Chain): Rotational misalignment in deployed chain leading to fatigue and damage, managed by anchor swivels and proper retrieval.

U

U.S. Coast Guard Mooring Standards: 33 CFR and NVIC guidance applicable to US-flag ships and to terminals in US waters, complementing OCIMF MEG4 for international tanker terminals.