Under keel clearance management
Maintaining the vertical distance between your ships hull and the ocean floor keeps the keel free of the seabed and reduces the chances of running aground.
What is under keel clearance management?
The under keel clearance management (UKCM) system helps large ships to navigate through the Torres Strait in Australia's north.
The system implemented by AMSA, for use by coastal pilots when transiting ships with a draught greater than nine metres through Torres Strait, calculates the depth of water underneath the keel throughout the transit in near real-time, taking account of a number of variables, including the height of tide, the speed of the ship, the ship’s squat, tidal streams and the dynamic motions of the vessel.
The UKCM system receives input from a number of sensors deployed at various locations through the system’s area of operations, as well as data from the ship via the ship’s onboard Automatic Identification System (AIS).
UKCM for ships transiting Torres Strait
Bulk carriers and tankers
Bulk carriers and tankers can pass through Torres Strait with a maximum draught up to 12.5 metres, using the UKCM system.
This change is contained in Marine Order 54 (Torres Strait draught variation) – Exemption 2019 (No.3), which took effect on 22 July 2019.
The change to maximum draught, came about following extensive at-sea trials and a comprehensive analysis report which validated the accuracy of the UKCM system for vessels up to 12.5 metres draught, when transiting Torres Strait.
While the maximum draught of vessels has increased, the amount of under keel clearance required has not changed.
A similar trial in collaboration with OMC International and Maersk has recently been completed to determine whether vessels with fine-form hulls (typically container vessels), can also safely pass through Torres Strait at certain times of the year, with draughts greater than 12.2 metres.
The draught limitation of 12.2 metres reflects the previous imperial measure of 40 feet, which was based on a study in the 1970’s by the then Federal Department for Transport.
Vessels with a draught of 12.2 metres were thought to be able to pass through Torres Strait on any day of the year while maintaining the required under keel clearance, but were restricted to conducting the transit during projected periods of high water.
Following the introduction of compulsory pilotage in Torres Strait in 2006, a study investigated whether a new method could provide better safety margins and economic benefits.
The 2007 study recommended a UKCM system for vessels with draughts between 8 metres and 12.2 metres.
We declared the UKCM system ‘operational’ in December 2011.
Use of the UKCM system (by AMSA-licensed coastal pilots assigned to the transit of vessels through Varzin Passage, Gannet Passage and the Prince of Wales Channel) became a condition of pilotage providers’ licences in January 2014.
The requirement to use the system was included in Marine Order 54 (coastal pilotage), which came into effect on 1 July 2014.
- Read our coastal pilotage information about UKCM.