New Zealand’s Hydrographic Authority has released Edition 21 of the Notices to Mariners, containing official chart and navigation updates for local waters. While the latest changes are minor, they remain essential for keeping navigation data accurate and vessels safe at sea.
Small updates, big importance
Two key areas receive attention in this edition. At the Manukau Harbour Entrance, six subsurface scientific instruments have been deployed as part of ongoing research. Mariners are advised not to anchor, ground or fish near the marked coordinates and to navigate with care.
Charts affected: NZ 42, NZ 43, NZ 4314.
In the South Island, Milford Sound / Piopiotahi has seen updates to chart NZ 7621, reflecting new construction, revised depths, and navigation aids around the ferry terminal in Deepwater and Freshwater Basins. The changes include a new Light List entry (4465.5) for the Fresh Water Basin Breakwater Head.
Technical reminders
The International Hydrographic Organization (IHO) has released a free dataset allowing skippers to test their ECDIS (Electronic Chart Display and Information System) for correct display of new chart features. The tool can be downloaded from iho.int, and mariners are encouraged to run checks and report any issues to their system provider.
The notice also highlights updates to HF radio frequencies for Taupō Maritime Radio (ZLM), supporting communication up to 1,000 nautical miles.
Publications and safety notes
The New Zealand Nautical Almanac and Light List have been amended for areas including Marsden Cove, Sinclair Point, One Tree Point, Shell Cut Reach, and Milford Sound. Outdated entries have been deleted to improve accuracy. Mariners using printed editions should make these corrections manually.
Navigators are also reminded that local harbourmasters issue additional Local Notices to Mariners, and these should be checked regularly, particularly in Auckland and other high-traffic regions.
Staying current
Though this round of updates may appear routine, the Hydrographic Authority stresses the importance of accuracy. Even small changes — a new buoy, an instrument deployment, or a depth revision — can make a difference when you’re navigating close to shore or in poor visibility.
Skippers can report new or suspected hazards directly to ntm@linz.govt.nz, or consult the Maritime NZ and AMSA websites for live coastal and NAVAREA warnings.
