45 terms starting with I.
- IACS Polar Class
Seven-tier ice class (PC1–PC7) under IACS UR I assigning ice-going capability from year-round in all polar waters (PC1) to summer-only thin first-year ice (PC7).
- Iceberg
Mass of glacier ice >5 m above the water, classified small/medium/large/very large by IIP.
- Icebreaker
Vessel with reinforced bow, high-power propulsion, and ice-friendly hull form designed to break level ice and clear channels.
- IGF Code
International Code of Safety for Ships using Gases or other Low-flashpoint Fuels.
- IMDG Class 1 (Explosives)
IMDG dangerous-goods classification for explosive substances and articles.
- IMDG Class 2 — Gases
Compressed, liquefied, or dissolved gases; subdivided 2.1 flammable, 2.2 non-flammable non-toxic, 2.3 toxic.
- IMDG Class 3 — Flammable Liquids
Liquids with flash point ≤ 60 °C; classified by packing group I/II/III based on flash point and boiling point.
- IMDG Class 4
Flammable solids (4.1), substances liable to spontaneous combustion (4.2), substances which emit flammable gases when wet (4.3).
- IMDG Class 5
Oxidising substances (5.1) and organic peroxides (5.2); pose fire risk by yielding oxygen.
- IMDG Class 6
Toxic substances (6.1) and infectious substances (6.2).
- IMDG Class 7 (Radioactive)
IMDG dangerous-goods classification for radioactive material.
- IMDG Class 8 — Corrosives
Substances causing severe damage when in contact with living tissue or other goods, including most acids and bases.
- IMDG Class 9 (Miscellaneous Dangerous Goods)
Catch-all for substances dangerous in transport but not fitting Classes 1-8 (e.g., asbestos, dry ice, lithium batteries, env. hazardous).
- IMDG Code
International Maritime Dangerous Goods Code — mandatory packaging, marking, segregation, and stowage rules for DG in packaged form.
- Immersion Suit
A watertight thermal protective suit worn in cold water abandonment that significantly extends survival time.
- IMO 2020 Sulphur Cap
Global cap on marine fuel sulphur content reduced to 0.50% mass on 1 January 2020 (0.10% in ECAs).
- IMO GHG Strategy
IMO 2023 strategy targeting net-zero GHG emissions from international shipping 'by or around' 2050, with checkpoints for 2030 and 2040.
- IMO Number
A unique seven-digit identifier assigned to a ship for life, used to track its history regardless of flag, owner, or name changes.
- Impressed Current Cathodic Protection (ICCP)
Active corrosion protection injecting low-voltage DC into the hull via inert anodes; used on most large vessels.
- Inert Gas System (IGS)
A system supplying inert gas (flue gas or nitrogen) to tanker cargo tanks to maintain an oxygen-deficient atmosphere and prevent explosion.
- Inmarsat-C
Geostationary satellite system providing low-data-rate store-and-forward messaging and EGC SafetyNET broadcasts, recognised under GMDSS for Sea Area A3.
- Innocent Passage
The right of foreign ships to navigate through a coastal state's territorial sea continuously and without prejudice to its peace or security.
- Inshore Traffic Zone (ITZ)
The water between a traffic separation scheme and the adjacent coast, normally reserved for local and small craft traffic.
- Intact Stability Code (IS Code)
IMO mandatory code for intact stability of all ships >24 m, including weather criterion and severe wind & rolling.
- Inter-Tropical Convergence Zone (ITCZ)
A belt of converging trade winds near the thermal equator characterised by squalls, doldrums, and heavy rain, migrating seasonally with solar heating.
- Intercept
In celestial navigation, the difference in minutes of arc between the observed altitude and the calculated altitude, used to plot a position line.
- Intermediate Fuel Oil (IFO)
A blend of heavy residual and distillate fuel oil with viscosity typically 180 or 380 cSt, used as main engine bunker.
- Intermediate Survey
A classification survey conducted midway through the five-year special survey cycle, typically around the second or third year.
- International Association of Classification Societies (IACS)
A body of twelve major classification societies that collectively establish and promote uniform technical standards for ship construction and maintenance.
- International Convention for the Prevention of Pollution from Ships (MARPOL)
The main international convention covering prevention of pollution of the sea by ships from operational and accidental causes.
- International Convention for the Safety of Life at Sea (SOLAS)
The primary IMO convention setting minimum safety standards for ship construction, equipment, and operation.
- International Group of P&I Clubs (IGP&I)
Association of 12 mutual P&I clubs sharing claims via a pooling/reinsurance arrangement covering ~90% of world tonnage.
- International Maritime Dangerous Goods Code (IMDG)
IMO code governing the safe carriage of hazardous materials by sea, covering classification, packing, marking, and stowage.
- International Regulations for Preventing Collisions at Sea (COLREGs)
IMO rules prescribing conduct of vessels to prevent collisions, including lights, shapes, sound signals, and steering rules.
- International Safety Guide for Oil Tankers and Terminals (ISGOTT)
Industry standard guidance jointly published by OCIMF, ICS, and IAPH for oil-tanker / terminal cargo operations.
- International Safety Management Code (ISM Code)
IMO code requiring shipping companies to establish a Safety Management System to ensure safe ship operation and pollution prevention.
- International Ship and Port Facility Security Code (ISPS Code)
IMO code mandating security plans, officers, and assessments for ships and port facilities to prevent terrorism and unlawful acts.
- Internationally Recommended Transit Corridor (IRTC)
Naval-monitored corridor through the Gulf of Aden with eastbound/westbound lanes for grouping and transit of merchant vessels.
- Intertropical Convergence Zone (ITCZ)
A band of low pressure near the equator where trade winds converge, producing persistent convective weather and squalls.
- Iridium GMDSS
IMO-recognised GMDSS satellite service using Iridium's low Earth orbit constellation, providing global coverage including polar Sea Area A4.
- Iridium GMDSS Service
Iridium satellite service recognised by IMO since 2020 for GMDSS Sea Areas A1–A4, including polar regions.
- ISM Audit
Internal and external audit of the Safety Management System under the ISM Code; underpins the DOC and SMC.
- ISO 8217
International standard specifying marine fuel grades — distillates (DMA, DMB, DMZ) and residuals (RMA, RMB, RMD, RME, RMG, RMK).
- ISPS Audit
Verification audit of ship/port-facility security plans under ISPS Code — initial, intermediate, renewal.
- ISPS Security Levels
Three-tier security alert: Level 1 normal, Level 2 heightened, Level 3 specific threat — set by Contracting Government.