As the UK’s leading energy port, Milford Haven serves as a busy gateway for ships, crew and cargo. The UK Hydrographic Office (UKHO) has been working closely with the Port of Milford Haven to develop more precise digital chart coverage and help mariners overcome navigational challenges in the area.


Understanding the navigational challenges

With so many vessels – both large and small – making use of this historic waterway, supporting safe and efficient navigation is a complex but crucial task.

The Milford Haven Waterway offers 22 miles of navigable water with an average depth of 15.5m; but as with any busy waterway, the area has its own unique navigational challenges.

Despite being one of the deepest natural harbours in the world, large commercial vessels must navigate carefully through its narrow channels – requiring deep-draught vessels to keep strictly on track with limited manoeuvrability. In some areas, the channel width is reduced to under 200m, meaning that only one large vessel can move at a time. Here, the under-keel clearance can be as little as 1m, requiring skilled navigation and a confident understanding of the true depth of water underneath the keel.

Where the channels narrow, this can create navigational ‘pinch points’ – particularly for congested areas where both inbound and outbound vessels are changing their course. These areas can be particularly challenging in certain conditions due to the strong tidal currents and heavy swell.


Enhancing navigation with HD ENCs

To transit this busy and narrow waterway, detailed navigational information is needed for mariners to make safe passage with confidence and precision.

This navigational precision is something that is afforded by ‘high-density’ Electronic Navigational Charts (HD ENCs). HD ENCs are contoured at one-metre intervals, enabling users to choose the most appropriate safety contour for the draught of their vessel and allowing them to navigate safely through high-traffic, shallow waterways such as Milford Haven.

By working closely with the Port of Milford Haven, the UKHO was able to develop four HD ENCs covering the waterway of Milford Haven to help support safe navigation in this area, while taking into account the pilots’ local knowledge and specific navigational challenges.

The ENCs were compiled using detail-rich bathymetric surveys coordinated by the port and consultants Anthony D Bates Partnership LLP, which were conducted using a multibeam echosounder to capture high-fidelity data on the depth and nature of the seabed. The UKHO also collaborated with MHPA staff to test the ENC cells in the port’s marine navigational suite, enabling them to simulate changing weather conditions, tidal currents, ship traffic and other navigational hazards.

As a result, the UKHO’s cartographic experts were able to produce chart coverage of the area with one-metre contours, providing vessels with more navigable space to enter and exit the waterway. This has helped to address the navigational ‘pinch points’ and has enabled pilots to use parts of the channel that they would have been unable to in the past.

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