Glossary — S

84 terms starting with S.

• Sacrificial Anode
  Block of zinc or aluminium attached to the hull that corrodes preferentially, protecting steel; used in addition to or instead of ICCP.
• 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.
• Safety Construction Certificate
  The SOLAS certificate evidencing the ship's structural + machinery + electrical compliance — issued after class + flag survey.
• Safety Management Certificate (SMC)
  A certificate issued to a ship confirming its Safety Management System is operating in accordance with the ISM Code.
• SafetyNET
  The Inmarsat-C broadcast service transmitting maritime safety information including navigational warnings and weather forecasts in GMDSS Areas A3/A4.
• SafetyNET
  Inmarsat-C EGC broadcast service delivering Maritime Safety Information to vessels in ocean areas A3, used as the satellite component of the GMDSS MSI distribution system.
• SafetyNET
  Inmarsat Enhanced Group Call service used to broadcast Maritime Safety Information to GMDSS Sea Areas A3 and A4.
• Sagging
  Longitudinal hull bending where the middle is unsupported between two wave crests, putting the deck in compression and the bottom in tension.
• Salvage Award
  Sum payable to salvors fixed by tribunal/court, considering value salved, danger, skill, and prevention of environmental damage.
• Scantlings
  Dimensions (thickness, depth, spacing) of structural members — plating, frames, stiffeners, girders — set by class rules.
• Scavenge Air
  Pressurised air supplied to the cylinder of a two-stroke diesel engine to expel exhaust gases and supply fresh charge for combustion.
• Scavenge Fire
  Fire in the scavenge air space of a two-stroke crosshead engine, ignited by leaking fuel + carbon deposits + scavenge air.
• SCBA (Self-Contained Breathing Apparatus) (SCBA)
  Portable breathing set used for fire-fighting + enclosed-space entry — self-contained compressed-air cylinder + face mask + demand valve.
• Scope of Cable
  Length of anchor chain veered, expressed as a multiple of water depth (e.g., 6× depth).
• SCOPIC Clause
  Special Compensation P&I Club clause attached to Lloyd's Open Form (LOF) salvage agreements, replacing the unworkable Article 14 of the Salvage Convention 1989.
• Scrubber Discharge Bans
  Local prohibitions (Singapore, China, UAE Fujairah, several EU/US ports) on washwater discharge from open-loop EGCS.
• SEA (Seafarer Employment Agreement) (SEA)
  The seafarer's individual employment contract required under MLC 2006 Standard A2.1.
• Sea Fog
  Advection fog formed when warm, moist air moves over a cooler sea surface, reducing visibility to less than 1,000 metres.
• Sea State
  A description of wave conditions at a given location, typically expressed by significant wave height and period.
• Sea Waybill
  Non-negotiable transport document acting as cargo receipt and contract of carriage, delivered to the named consignee on identification.
• Seafarer Employment Agreement (SEA)
  Written contract between seafarer and shipowner required by MLC 2006; sets terms of employment, repatriation, leave, and complaint procedures.
• Search and Rescue Transponder (SART)
  A radar transponder that responds to X-band radar pulses to indicate the position of a survival craft to SAR aircraft and vessels.
• Second Engineer (2/E)
  The engineer officer second in command, directly overseeing day-to-day operation and maintenance of the main propulsion plant.
• Second Mate (2/O)
  A certificated deck officer responsible for navigation equipment, charts, publications, and often designated ship's safety officer.
• SEEMP
  Ship Energy Efficiency Management Plan: mandatory document detailing measures to monitor and improve ship energy efficiency.
• Segregation
  The physical separation of incompatible dangerous goods in stowage to prevent hazardous reactions if packaging fails.
• Selective Catalytic Reduction (SCR)
  Exhaust after-treatment that injects urea into hot exhaust gas, converting NOx to N2 and water on a vanadium-titanium catalyst.
• Self-Contained Breathing Apparatus (SCBA)
  A compressed-air breathing set worn by firefighting team members to allow entry into oxygen-deficient or toxic atmospheres.
• semi-submersible (semi-sub)
  Column-stabilised offshore unit with submerged pontoons providing stability for drilling, accommodation, or production in deepwater and harsh environments.
• Semi-Submersible Rig
  Floating MODU with submerged pontoons supporting the operating deck on columns, station-kept by anchors or DP.
• service operations vessel (SOV)
  Offshore wind-farm support vessel with motion-compensated walk-to-work gangway, long-stay accommodation, and DP-2 positioning for technician transfers.
• Sewage Treatment Plant (STP)
  A biological or chemical system treating shipboard sewage to standards permitting overboard discharge under MARPOL Annex IV.
• Sextant
  A precision optical instrument used to measure the angle between a celestial body and the horizon for position fixing.
• Shaft Alley
  The enclosed tunnel running through the stern of the ship enclosing the propeller shaft from the engine room to the stern tube.
• Shell Plating
  Outer steel skin of the hull from keel to deck edge.
• Shelltime
  Shell-issued tanker time charter party form, currently Shelltime 4 (1984, amended 2003).
• Shifting (berth)
  Movement of a vessel from one berth to another within the same port, typically without loading/discharging operations underway.
• Ship Agent
  Local representative arranging port services (pilots, tugs, stores, crew changes, customs) on behalf of the owner or charterer.
• Ship Security Officer (SSO)
  The officer on board responsible for implementing and maintaining the Ship Security Plan and liaising with the CSO and port facility security.
• Ship Security Plan (SSP)
  Confidential, ship-specific plan implementing the ISPS Code; approved by the Administration or RSO on its behalf.
• Ship-to-Ship Transfer (STS)
  The transfer of cargo between two vessels moored alongside each other at sea or in an anchorage.
• Ship's Cook
  A certificated crew member responsible for preparing all meals and maintaining hygiene standards in the ship's galley.
• Ship/Shore Link (SSL)
  Hardwired signalling cable between ship and terminal for ESD and safety status during cargo transfer.
• Ship/Shore Safety Checklist (SSSCL)
  Mandatory pre-cargo-transfer checklist verified jointly by ship and terminal representatives.
• Shipboard Marine Pollution Emergency Plan (SMPEP)
  Combined SOPEP + Annex II NLS pollution plan required for ships carrying noxious liquid substances.
• Shipboard Oil Pollution Emergency Plan (SOPEP)
  MARPOL Annex I plan giving guidance to the master and officers in the event of an oil pollution incident.
• SID (Seafarers' Identity Document) (SID)
  The biometric international ID document for seafarers issued under ILO Conventions 108 + 185.
• Sight Reduction
  The mathematical process of converting a celestial observation into a position line using tables or a calculator.
• Significant Wave Height (Hs)
  Statistical measure of sea state: average height of the highest one-third of waves observed.
• SIRE 2.0
  OCIMF Ship Inspection Report Programme version 2.0 — risk- and behaviour-based tanker inspection regime, fully active 2024.
• Slamming
  Impact of the bow re-entering the water after pitching out, causing localised pressure spikes on the forefoot and forward bottom.
• Slop Tank
  A dedicated tank on tankers used to collect cargo residues and tank washing water, allowing oil-water separation before discharge.
• SMC (Safety Management Certificate) (SMC)
  The ISM Code certificate issued to each individual ship after a ship-side audit — evidences that the ship's SMS is implemented + effective.
• Snap-Back Zone
  Area on deck within which a parted mooring line can whip back; standing in this zone has killed many seafarers.
• Snap-Back Zone Marking
  Painted/marked deck areas indicating recoil danger from a parted line; revised guidance in MEG4 (2018).
• SOLAS (International Convention for the Safety of Life at Sea) (SOLAS)
  The foundational IMO convention on merchant-ship safety — construction, life-saving, fire, navigation, radiocommunication, dangerous goods, and safety management.
• SOLAS Chapter III
  The chapter of SOLAS covering life-saving appliance requirements including lifeboats, liferafts, immersion suits, and drills.
• SOLAS Chapter IX
  The chapter of SOLAS making the ISM Code mandatory for ships, requiring companies to hold a Document of Compliance.
• SOLAS Chapter V
  The chapter of SOLAS dealing with safety of navigation, requiring ECDIS, AIS, VDR, pilot ladders, and bridge watchkeeping standards.
• SOx Emission Control Area
  Designated sea area where 0.10% sulphur cap applies — Baltic, North Sea, North America, US Caribbean, Mediterranean (from 2025).
• Special Survey
  A comprehensive five-yearly classification survey requiring drydocking and full structural inspection to renew class for a further five years.
• Spring Line
  A mooring line leading forward or aft at a shallow angle to prevent the ship from moving ahead or astern.
• Springing
  Steady-state hull-girder resonance excited by encounter waves at or near the natural frequency.
• Squall
  A sudden, brief and intense increase in wind speed often accompanied by rain or hail, posing an immediate hazard to vessels.
• Standards of Training, Certification and Watchkeeping (STCW)
  International convention setting minimum training, certification, and watchkeeping standards for merchant ship officers and crew.
• Starlink Maritime
  SpaceX low-earth-orbit broadband; offers high bandwidth at sea but is not yet GMDSS-recognised.
• Starting Air Receiver
  A pressure vessel storing compressed air at 30 bar used to crank and start the main engine and diesel generators.
• STCW (Standards of Training, Certification and Watchkeeping) (STCW)
  The IMO convention setting the international minimum standards for seafarer training, certification, and watchkeeping.
• STCW Flag Endorsement
  Document issued by a flag state recognising another state's STCW CoC for service on its flag — often called a 'flag endorsement' or 'recognition endorsement'.
• STCW Medical Fitness Certificate
  Medical certificate confirming a seafarer meets STCW Reg. I/9 and ILO MLC standards for vision, hearing, and general health.
• Stern Tube
  The watertight bearing assembly through which the propeller shaft passes through the hull from the engine room to the propeller.
• Stockless Anchor
  Most common modern bower anchor type — flukes pivot independently to dig in regardless of orientation.
• Stowage Factor (SF)
  The volume in cubic metres or cubic feet that one metric tonne of a commodity occupies when stowed in a ship's hold.
• Stowage Plan
  A diagram showing the planned or actual position of all cargo units aboard a vessel for a given voyage.
• Stowaway
  Person who hides aboard a ship to gain free passage or escape circumstances ashore, without consent of the operator.
• Subrogation
  Insurer's right, after paying a claim, to step into the insured's shoes and pursue recovery from the wrongdoer.
• Suez Canal Transit
  Transit through the Suez Canal between Port Said and Suez, 193 km, no locks, governed by the Suez Canal Authority.
• Suezmax
  Crude tanker sized to fully transit the Suez Canal in laden condition — typically 120,000-200,000 DWT, ~250 m LOA, ~17 m draft.
• Summer Draft
  The maximum permissible draft when loading in a Summer load line zone, shown on the ship's side as the Summer load line mark.
• Supercargo
  A cargo owner's representative sailing aboard a vessel to oversee the handling and care of the cargo throughout the voyage.
• Supramax / Ultramax
  Mid-size geared bulkers ~50,000-65,000 DWT; Ultramax is the slightly-larger evolution at ~63,000-65,000 DWT.
• Swell
  Long-period regular waves that have travelled out of the generating area, independent of current local wind conditions.
• SWL vs MBL
  Safe Working Load is the in-service rating; Minimum Breaking Load is the failure load. SWL = MBL / safety factor (typically 5).
• Syncrolift
  Mechanical ship-lift platform raising vessels onto land for transfer to repair berths; used by smaller yards.