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 SC142 Deleted

UI SC142 Embarkation Ladders & Survival Craft Launching Falls (Chapter III, Regulations 11.7 & 16.6) Deleted in January 2000. 

UI SC143 Rev1 CLN

UI SC143 Stowage of Marine Evacuation Systems SOLAS Regulation III/15.1 - Rev.1 February 2010 Clean

UI SC144 Rev2 CLN

UI SC144 Periodic Servicing of Launching Appliances and on-load Releasing Gear SOLAS Regulation III/20.11 - Rev.2 September 2012 Clean

Note: UI SC144 Rev.3 will come into force on 1 January 2020 and can be found in "Previous Revisions"

UI SC145 New

UI SC145 Public Address System (LSA Code, para. 7.2.2) - 1998

UI SC146 Rev1 CLN

UI SC146 Fire hose couplings and nozzles (Reg. II-2/10.2.3) - Rev.1 Nov 2005

UI SC147 Rev1 CLN

UI SC147 Watertight door closure (FSS Code, Ch. 9, 2.1.2) - Rev.1 Nov 2005

UI SC148 Rev2 CLN

UI SC148 Ventilation by fan coil units and internal circulation fans (Reg.II-2/, II-2/ and Reg.II-2/7.9.3) - Rev2 September 2015 Clean

UI SC149 Rev2 CLN

UI SC149 Gas Measurement and Detection - Portable instruments (SOLAS Reg. II-2/ - Rev.2 February 2012 Clean

UI SC150 Rev1 CLN

UI SC150 Location of the foam system equipment (FSS Code, Ch. 14, 2.1.2 and 2.3.1) - Rev.1 Nov 2005

UI SC151 New

UI SC151 Location of the main generating station with respect to the main switchboard and associated section boards (Chapter II-1, Reg. 41.3) - May 1999

UI SC152 New

UI SC152 Use of emergency generator in port (Chapter II-1, Regulations 42.1.4 and 43.1.4) - May 1999

UI SC153 New

UI SC153 Rudder Stock Diameter (Reg.II-1/29.3.3, 29.4.3 and 29.14) - February 2000

UI SC154 New

UI SC154 Provision of Detailed Information on Specific Cargo Hold Flooding Scenarios (SOLAS XII/9.3) - March 2000

UI SC155 Rev2 CLN

UI SC155 Lightweight check in lieu of inclining test Regulation II-1/22 - Rev.2 February 2010 Clean

UI SC156 New

UI SC156 Doors in watertight bulkheads of cargo ships and passenger ships - June 2002

UI SC157 Rev1 CLN

UI SC157 Main Source of Electrical Power (Regulation II-1/41.5) - Rev.1 Feb 2005

UI SC158 Rev1 CLN

UI SC158 Horizontal fire zone concept (Reg. II-2/ - Rev.1 Nov 2005

UI SC159 Rev1 CLN

UI SC159 Equivalent Protection (Reg. II-2/10.7.2) - Rev.1 Nov 2005

UI SC160 Rev1 CLN

UI SC160 Method IIIC Construction (Reg. II-2/ - Rev.1 Nov 2005

UI SC161 Rev1 CLN

UI SC161 Timber deck cargo in the context of damage stability requirements SOLAS Regulation II-1/5-1 - Rev.1 Feb 2008

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