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Chapter 4.9
Services rendered by the Hydrographic Office
Contributor: Tam Kwong-lim

The Hong Kong Marine Department Hydrographic Office (HKHO) was inaugurated in 1995. By that time, less than 20 percent of Hong Kong waters had been properly surveyed by the Royal Navy survey vessels. The remaining 80 percent was either not adequately surveyed or the data was outdated. Despite the problems faced, the team has continued to make efforts and raise the standards of its work. Eventually, in 2010, the whole chart series of Hong Kong was finally completed.

Today, the services of the HKHO include conducting bathymetric surveys and collecting hydrographic data for compilation of nautical charts. These charts show coastal details, water depths, seabed features, locations of dangers, details of tidal levels, locations and characteristics of navigational aids, delineations of fairways, anchorages, traffic separation schemes, and other supplementary information.

To keep all charts up-to-date, the HKHO issues bi-weekly Notices to Mariners, which can be downloaded from its website. Other than A0-size nautical charts of the Hong Kong Region in scales from 1:8000 to 1:75000, there is a condensed version of the charts in scales and details useful for smaller craft trading within the territory of Hong Kong, which is in book form and entitled “Charts for Local Vessels”. “HK Chart 1”, which details the symbols, abbreviations and terms used on nautical charts, is also in book form. Moreover, there is an informative wall chart named “Hong Kong Harbour Facilities and Layout” which gives information on speed limits for vessels within Hong Kong waters, VHF Sectors and Ma Wan Marine Traffic Controls, as well as important information such as vessel traffic services, procedures for entering and departing Hong Kong, pilotage services, harbour moorings, typhoon shelters, and marine refuse and pollution controls.

The HKHO manages eleven tidal gauges throughout the region together with the Hong Kong Observatory and the Airport Authority to provide real-time tidal information. Due to the strong tidal currents prevalent in the Ma Wan Channel that may endanger the navigation of large vessels, the Marine Department imposes restrictions on the transit period for large bulkers or tankers. The HKHO also manages the Ma Wan transit tidal window webpage to facilitate port users.

By erecting a permanent differential Global Positioning System (GPS) reference station on top of Kau Yi Chau in 1996, HKHO has been able to continuously monitor GPS status and broadcast differential signals. The broadcast service is free. Any user equipped with a standard differential GPS receiver is able to access the signals to improve the accuracy of their GPS positions.

Survey data collection is mainly undertaken by three specialised hydrographic survey vessels. The Hydro 1 is a replacement launch commissioned in January 2003, with a length of 13.7 metres and capable of cruising at 18 knots. The Hydro 2 is a catamaran, a specially designed hydrographic survey ship built in America. She has a length of 18 metres and a cruising speed of 12 knots. The Hydro 3 is a small Boston-Whaler-type boat of 7 metres in length and has a cruise speed of 20 knots. Her small size is ideal for survey work in shallow shoreline areas. All survey vessels are equipped with up-to-date instruments such as multi-beam echo sounders with side-scan sonar functions. Such modern technology enables precise data to be collected, and the position of underwater wreckage to be determined and surveyed to make shipping routes safe for navigation.

In addition to nautical charts on paper, HKHO also produces, in accordance with international standards, electronic navigational charts (ENCs) that contain all the official chart information for use onboard ships equipped with an Electronic Chart Data Display and Information System (ECDIS). When ECDIS is interfaced with navigational sensors such as differential GPS, Automatic Radar Plotting Aid (ARPA) and Automatic Identification System (AIS), it can display real-time ship positions in relation to land, charted objects, submerged dangers, and early grounding and collision warnings. The system is also capable of carrying out route planning and route monitoring.

The International Maritime Organization has resolved that all merchant ships should be installed with ECDIS in a rolling timetable commencing in July 2012 and concluding in 2018, by which time it is hoped that all ships will be suitably equipped.

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