Glossary — deck

Mooring, anchoring, cargo work, deck maintenance, rigging.

38 terms in this category.

• Able Seaman (AB)
  Certified deck rating with a minimum of 18 months sea service, competent in watchkeeping, mooring, and cargo handling.
• Anchor Watch
  Continuous bridge / deck watch monitoring position, swing, and chain tension to detect dragging.
• Bahamian Moor
  Mooring with both bow anchors set roughly 180 deg apart, restricting the swing circle in tight anchorages.
• Bitter End
  Inboard end of the anchor chain secured in the chain locker; from which 'to the bitter end' is derived.
• Block Coefficient (Cb)
  Ratio of underwater volume to a rectangular block of length × beam × draft.
• Bosun
  Senior unlicensed deck rating responsible for the upkeep of deck equipment, mooring gear, and supervision of the deck crew.
• Capstan
  A vertical-axis powered drum on deck used to heave in mooring lines or warping lines.
• Draft
  The vertical distance between the keel and the waterline, determining the minimum water depth needed for safe navigation.
• Draught Marks (draught scale)
  Numeric scale painted on the bow, mid, and stern of the ship indicating the depth of submergence at that point.
• Fender
  A cushioning device of rubber, foam, or rope placed between a vessel and a berth or another vessel to prevent damage.
• Freeboard
  The vertical distance from the waterline to the main deck edge, indicating reserve buoyancy and load line compliance.
• Gangway
  A portable access ladder or bridge rigged over the ship's side to allow persons to embark and disembark safely.
• Gob Rope
  Restraining line led from the towing point on a tug to a deck winch, controlling the angle of the towline.
• GZ Curve (GZ)
  Plot of the righting arm (GZ) against angle of heel — the cornerstone of intact-stability assessment.
• Hawser
  A large rope or cable used for mooring or towing a vessel, typically greater than 25mm in diameter.
• HMPE Mooring Line (HMPE)
  High-Modulus Polyethylene synthetic mooring line — strength similar to steel wire at a fraction of the weight.
• Lightweight Tonnage (LWT)
  Ship's mass when launched, empty: hull, machinery, equipment, no fuel, water, ballast, stores, or cargo.
• List
  A permanent transverse inclination of a vessel caused by an uneven distribution of weights across the ship.
• Metacentric Height from Keel (KM)
  Vertical distance from keel to the metacentre M; sum of KB (keel to centre of buoyancy) and BM (metacentric radius).
• Mooring
  Securing a vessel to a berth, buoy, or anchor using lines, chains, or anchors to keep it stationary.
• Mooring Equipment Guidelines 4 (MEG4)
  OCIMF guideline (2018) for mooring system design, operation, and inspection of tankers and gas carriers.
• MoorMaster
  Cavotec vacuum mooring system replacing conventional lines in some ferry, container, and bulk berths.
• Open Moor
  Two anchors set with cables forming a wide V to limit swing in restricted anchorage.
• Ordinary Seaman (OS)
  Entry-level unlicensed deck rating assigned general duties under the supervision of ABs and the bosun.
• Parallel Mid-body
  Length of hull where cross-sections are constant (the 'box' between the entry and run sections).
• Pilot Ladder
  A rope side ladder rigged overside to enable a pilot to board or disembark from a ship at sea.
• Prismatic Coefficient (Cp)
  Ratio of underwater volume to volume of a prism with cross-section equal to the maximum hull section, length = LBP.
• Running Moor
  Anchoring with two anchors by laying the first anchor while making way ahead, then dropping the second after veering chain.
• Safe Working Load (SWL)
  The maximum load that lifting gear, mooring lines, or deck equipment is certified to bear without risk of failure in normal use.
• Scope of Cable
  Length of anchor chain veered, expressed as a multiple of water depth (e.g., 6× depth).
• Snap-Back Zone
  Area on deck within which a parted mooring line can whip back; standing in this zone has killed many seafarers.
• Spring Line
  A mooring line leading forward or aft at a shallow angle to prevent the ship from moving ahead or astern.
• Stockless Anchor
  Most common modern bower anchor type — flukes pivot independently to dig in regardless of orientation.
• SWL vs MBL
  Safe Working Load is the in-service rating; Minimum Breaking Load is the failure load. SWL = MBL / safety factor (typically 5).
• Towline
  Wire, fibre, or composite rope connecting tug to tow.
• Trim
  The difference between forward and aft draft; a vessel trims by the head if forward draft exceeds aft draft.
• Vertical Centre of Gravity (KG)
  Vertical distance from the keel to the ship's centre of gravity. Lower KG = more stable.
• Windlass
  A powered deck machine used to heave in or pay out anchor chain and sometimes mooring lines.