Unified Interpretations


Unified Interpretations are adopted resolutions on matters arising from implementing the requirements of IMO Conventions or Recommendations. Such adopted resolutions can involve uniform interpretations of Convention Regulations or IMO Resolutions on those matters which in the Convention are left to the satisfaction of the Administration or vaguely worded.

Interpretations are circulated to Administrations concerned or are sent to IMO for information, as appropriate.


  1. IACS, as an international Non-Governmental Organization having observer status at IMO, works in co-operation with IMO in order to endeavour that regulations developed at IMO are clear, unambiguous and can easily be applied without the need of interpretations.
  2. However, interpretations may still be needed in cases where IMO regulations contain only functional requirements, allow alternative solutions to prescriptive requirements, are left to the satisfaction of Administrations or are generally or vaguely worded.
  3. The following Unified Interpretations (UIs) have been developed by IACS to assist the unified implementation of IMO regulations falling in the above-mentioned cases. It should be noted that the development of IACS Unified Interpretations (UIs) is not aiming at introducing additional requirements but at achieving uniform application of IMO regulations.
  4. IACS UIs are to be applied by IACS Societies to ships whose flag Administrations have not issued definite instructions on the interpretation of the IMO regulations concerned, in the course of statutory certification on behalf of those flag Administrations.

The technical backgrounds (development histories) of Unified Interpretations since 2004 can be found by following this link.

A list of the IACS working groups responsible for each Unified Interpretation may be found here.

UI SC271 New

UI SC271 Additional indicating unit in the cargo control room in accordance with amended FSS Code Chapter - January 2015

UI SC272 Rev1 CLN

UI SC272 Inert gas supply to double-hull spaces (SOLAS II-2/ - Rev.1 July 2016 Clean

UI SC273 Rev1 CLN

UI SC273 Inclusion of mediums of the fire-fighting systems in lightweight (SOLAS II-1/2.21, SOLAS II-2/3.28) and lightship condition (IS Code 2008 Paragraph 2.23) - Rev.1 May 2016 Clean

UI SC274 New

UI SC274 Hazardous area classification in respect of selection of electrical equipment, cables and wiring and positioning of openings and air intakes - December 2015

UI SC275 Rev1 CLN

UI SC275 Suitable number of spare air cylinders to be provided in connection with drills - Rev.1 September 2016 Clean

UI SC276 New

UI SC276 Escape from machinery spaces on passenger ships SOLAS Chapter II-2, Regulation 13.4.1 - January 2016

UI SC277 New

UI SC277 Escape from machinery spaces on cargo ships SOLAS Chapter II-2, Regulation 13.4.2 - January 2016

UI SC278 New

UI SC278 Escape from accommodation spaces, service spaces and control stations on cargo ships SOLAS Chapter II-2, Regulation and - January 2016

UI SC279 New

UI SC279 Annual testing of VDR, S-VDR, AIS and EPIRB

- SOLAS regulation V/18.8 - Annual performance test of Voyage Data Recorder (VDR) and Simplified Voyage Data Recorder (S-VDR)

- SOLAS regulation V/18.9 - Annual performance test of Automatic Identification System (AIS)

- SOLAS regulation IV/15.9 - Annual test of EPIRB

June 2016

UI SC280 New

UI SC280 Angle of down-flooding (ϕf) / Angle at which an opening incapable of being closed weathertight (θv) (2008 IS Code, International Grain Code, SOLAS/Ch.II-1-Reg.7-2) - June 2016

UI SC281 Del

UI SC281 Single fall and hook system used for launching a lifeboat or rescue boat - Interpretation of the LSA Code as amended by MSC.320(89) and MSC.81(70) as amended by MSC.321(89) - Withdrawn June 2017

UI SC282 New

UI SC282 Application of materials other than steel on engine, turbine and gearbox installations - Dec 2016


Tonnage Measurement

UI TM1 New

UI TM1 Determination of Moulded Depth (D) for Ships with an Open Mooring Deck Aft or Stepped Upper Deck - 1993

UI TM2 New

UI TM2 International Tonnage Convention 1969 - Heat Exchangers (Coolers) Treatment - October 2015

UI TM3 Deleted

UI TM3 Interpretation of International Tonnage Calculation: Open Deck Spaces Bounded by Partitions or Bulkheads (ITC69 regulation 2(4), 2(5) and 6) Withdrawn April 2016.

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