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 LL66 New

UI LL66 Hatch Cover Stress/Deflection Calculation - Oct 2003

UI LL67 Rev1 CLN

UI LL67 Endorsement of Certificates with the Date of Completion of the Survey on which they are Based - Rev.1, Nov. 2005 Clean

UI LL68 Rev1 CLN

UI LL68 Position of Freeboard Deck on Float On/Float Off Barge Carriers - Rev.1 July 2008 Clean

UI LL69 Rev1 CLN

UI LL69 Interpretation to 1966 ICLL Reg. 27 - Rev.1 July 2008

UI LL71 Rev1 CLN

UI LL71 Similar stage of construction - Rev.1 July 2008 Clean

UI LL72 New

UI LL72 Interpretation to ICLL Regulation 27 - Sept 2005

UI LL74 New

UI LL74 Measurement of Distances - Aug 2008

UI LL75 Rev1 CLN

UI LL75 Permeability of Store Space in the Damage Stability Calculation (Regulation 27(3) & (8.d)) - Rev.1 Mar 2009 Clean

UI LL76 Deleted

UI LL76 Deleted June 2016

UI LL77 New

UI LL77 Application of Load Line Requirements to Conversions of Single-hull Oil Tankers to Double-hull Oil Tankers or Bulk Carriers - Dec 2011

UI LL78 Corr1 CLN

UI LL78 Keel Laying Date for Fibre-Reinforced Plastic (FRP) Craft - Corr.1 January 2014 Clean

UI LL79 New

UI LL79 Continuous hatchways (Regulation 36(6)) - July 2014

UI LL80 New

UI LL80 Unprotected openings June 2016


Interpretations of the Mobile Offshore Drilling Units (MODU)

UI MODU1 Rev1 Corr1 CLN

UI MODU1 IACS Unified Interpretations for the application of MODU Code Chapter 2 paragraphs 2.1, 2.2, 2.3, 2.4 and revised technical provisions for means of access for inspections (resolution MSC.158(78)) - Rev.1 Corr.1 June 2016


UI MODU2 Inclusion of mediums of the fire-fighting systems in lightweight (2009 MODU Code Chapter 1, paragraph 1.3.30) - August 2016


MARPOL Convention

UI MPC1 Deleted

UI MPC1 Periodical surveys of oil content meters (Annex I, Regulation 15(3)) Deleted August 2015


UI MPC2 Operational manuals for oil discharge monitoring and control systems (Annex I, Regulation 31.4) - Rev.1 August 2015 Clean

UI MPC3 Deleted

UI MPC3 Machinery space oil discharge monitoring and control systems (Annex I, Regulation 16(5)) Deleted August 2015

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