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Thursday, 17 September 2020 10:52

Standardising International Definitions of Depths and Draughts

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A worldwide common understanding and definition of terms in connection with port design and daily operation is essential for safety, sustainability and efficiency and is the interest of all parties involved in waterborne transport. In a co-operation which started in 2006 during a congress of the International Harbour Masters Association (IHMA), ports and shipping lines have been working together to achieve that and can claim impressive results.

The priority has been to improve communications between ships and ports using clear and authoritative definitions for the various terms used in daily operations. The definitions have been sourced from existing standards within the shipping industry. Only when no applicable definition could be found was a new one introduced. The definitions include names given to areas within a port; terminology associated with restrictions that might be imposed by an authority on vessel operations related to vessel dimensions, external conditions, manoeuvring and berthing; event information associated with arrival and departure times; and nautical and vessel service times. These were incorporated in the 11th edition of the UKHO’s Mariners Handbook (NP100) (2016).

One of the co-operating partners, the International Taskforce Port Call Optimization, shared the terms used for vertical measurement of vessels, depth and draughts with CEDA’s Dredging Management Commission (DMC) during one of their meetings.

Standardising definitions to improve communication between ports and shipping lanes and other stakeholders is an ongoing process which is vital to the port call optimisation process . Co-operating organisations continue their important work with the next objective to improve data sharing between interested parties.

For further information visit the website of the International Taskforce Port Call Optimization , or contact IHMA: Ben van Scherpenzeel,



UKHO (2016). Admiralty. The Mariners Handbook (NP100).

IHMA &UKHO (2017). IHMA and UKHO Port information project: Functional definitions for nautical port information.


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