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 SC225 New

UI SC225 The occupied volume by flooded water of a flooded space in the SOLAS Chapter II-1 (Regulation 2(14)) - September 2008

UI SC226 Rev1 CLN

UI SC226 IACS Unified Interpretations (UI) on the application of SOLAS regulations to conversions of Single-Hull Oil Tankers to Double-Hull Oil Tankers or Bulk Carriers - Rev.1 December 2012 Clean

UI SC227 Rev2 CLN

UI SC227 The dedicated seawater ballast tanks in SOLAS Chapter II-1 (Regulation 3-2) - Rev.1 

UI SC228 New

UI SC228 Machinery shutoff arrangements - Oil mist detector arrangements SOLAS Regulation II-1/27.5: Machinery – Automatic shutoff arrangements - December 2008

UI SC232 New

UI SC232 Steam Boilers and Boiler Feed Systems SOLAS Reg. II-1/32.4  - May 2009

UI SC233 Rev1 CLN

UI SC233 LSA Code – lifeboat exterior colour LSA Code item as amended by MSC Res. 207(81) - Rev.1 November 2012 Clean

UI SC234 Deleted

UI SC234 Initial Statutory Surveys at New Construction Deleted June 2016.

UI SC235 Corr2 CLN

UI SC235 Navigation bridge visibility to ship’s side (Chapter V, Regulation 22) Corr.2 June 2013 Clean

UI SC239 New

UI SC239 Insulation with approved non-combustible materials (Reg. II-2/3.2.3) - June 2009

UI SC240 Corr1 CLN

UI SC240 Closing device for ventilation of battery rooms (SOLAS II-2/ - Corr.1 September 2011 Clean

UI SC241 New

UI SC241 Manually operated call points (SOLAS II-2/7.7) - November 2010

UI SC242 Corr 1 Reinstated CLN

UI SC242 Arrangements for steering capability and function on ships fitted with propulsion and steering systems other than traditional arrangements for a ship’s directional control (Chapter II-1, Regulations 29.1, 29.2.1, 29.3, 29.4, 29.6.1, 29.14, 28.3 and 30.2) - Corri1 Aug 2011 Reinstated Clean

UI SC243 Rev1 CLN

UI SC243 Access to controls for closing of ventilation of vehicle, special category and ro-ro spaces (SOLAS II-2/ - Rev1 May 2012 Clean

UI SC244 Rev1 Corr1 CLN

UI SC244 Load testing of hooks for primary release of lifeboats and rescue boats (IMO Res. MSC.81(70), Part 2, Ch. 5.3.4) -  Rev.1 Corr.1 November 2015 Clean

UI SC245 Corr1 CLN

UI SC245 Suction and discharge piping of emergency fire pumps, which are run through the machinery space (SOLAS II-2/ - Corr.1 January 2012 Clean

UI SC246 Rev1 CLN

UI SC246 Steering gear test with the vessel not at the deepest seagoing draught - Rev.1 September 2015 Clean

UI SC247 New

UI SC247 Emergency exit hatches to open deck (SOLAS Reg. II-2/13.1) - September 2011

UI SC248 Rev1 CLN

UI SC248 Greatest Launching Height for a Free-Fall Lifeboat (LSA Code 1.1.4) - Rev1 April 2015 Clean

UI SC249 Rev1 CLN

UI SC249 Implementation of SOLAS II-1, Regulation 3-5 and MSC.1/Circ.1379 - Rev1 February 2013 Clean

UI SC250 Corr1 CLN

UI SC250 Fire-Extinguishing Arrangements in Cargo Spaces (Res. MSC.268(85), IMSBC Code)  - Corr.1 July 2012 Clean

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