Increasing Draft Capacity

Dynamic Under-Keel Clearance (DUKC) technology is used within the Port of Fremantle to maximise ship drafts and ship loadings through the shipping channels.

Fremantle is a world leader in the operation of DUKC. The computerised system enables the clearance between the bottom of the ship and the ocean floor to be predicted to within centimetre accuracy. It means that those planning ship movements can further reduce the under-keel clearance required for safe passage, while continuing to meet international safety standards. For shipping lines, it allows an increase in draft. This means ships can come safely into port carrying larger cargoes, leading to savings in freight.

The technology, developed by O'Brien Maritime Consultants, was originally introduced by Fremantle Ports in Cockburn Sound on 20 April 1994 for BP Australia.

Fremantle Ports has had a significant input into modification of the technology for use in the Inner Harbour to enable the larger container ships to come safely into port carrying more cargo than would otherwise have been possible.

The technology is now applied through all channels in the port for the benefit of all ships that require it.

Fremantle Ports manages and controls application of Dynamic Under-Keel Clearance and is continuing to monitor and further develop the program.

Further Developments in DUKC

Since the introduction of Dynamic Under-Keel Clearance, the initial computer modelling used to analyse wave and tide conditions has undergone several refinements. The aim of this work is to enhance the reliability of the data used both in forecasting the maximum draft and in real time predictions of the under-keel clearance at the actual time of transit through the shipping channels.

Another associated project which Fremantle Ports believes has considerable benefits to offer is an analysis of the way in which a vessel "squats". The bow is forced downwards as the ship travels through the water, and it is known that the faster a ship travels, the more it squats. Better understanding of this phenomenon might be used to advantage in the future in deciding how best to distribute cargo to gain additional draft.