If a cyclone hit Napier, these guys would ensure help could arrive

For the past five weeks, a small navy ship has been doing vital training off the coast of Napier.

On face value, the survey motor boat Adventure doesn't look as impressive as the likes of the larger HMNZS Canterbury.

But it, and the team of hydrographers on board, are just what Hawke's Bay needs if a cyclone or earthquake were to hit.

They're responsible for ensuring it's safe for larger ships to bring in crucial supplies in the event of an emergency, when the seafloor is likely to have changed around it.

Opening ports and airports are a priority in an emergency situation - airports allow needed supplies to arrive quickly, and ports allow large quantities of heavy supplies in.

The team, led by Officer in Charge Lieutenant Stuart Lee, has been based in Napier since May 20.

"We go in and enable other specialist units to come in and fix any problems, we help with the initial emergency response," Lee said.

The team of hydrographers use sonar to map the seabed, noting any changes which may have occurred.

"The main concern is if a shipping container has fallen off the side of the dock or a ship, or has there been an uplift of the seabed changing the environment."

The first step is to make sure a big ship, such as the HMNZS Canterbury, can anchor in a safe place, in about 20m of water, close to a beach allowing supplies to be disembarked to assist as soon as possible.

Officer in Charge Lieutenant Stuart Lee, during an early morning run on the boat. Photo / Paul Taylor

So a team like the one from HMNZS Matataua in Auckland uses sonar by going back and forth along the beach, as well as gathering data on the beach itself using portable GPS recording equipment.

Once there is a safe anchorage, the team clears a route for the ships to get into the harbour.

"Which is similar to our main role, we are here training to ensure that we are able to survey an area to modern standards quickly and accurately."

"Working in Napier gives us the opportunity to work in a new place that presents different challenges to our base in Auckland."

This data is then compared to existing charts to check for any changes and if there are any new hazards to shipping in the area.

Lee is on exchange from the Royal Navy in Britain, and said working in situations where the geology may change dramatically is a new experience for him.

Although Napier has a relatively flat seabed, the challenges in New Zealand presented by volcanic activity causing steep drop-offs and uplifting of the seabed by earthquakes provide valuable new experiences.

While in Napier, the team will provide their data for Land Information New Zealand to update nautical charts in the area.

They are mapping an area which was last charted in the early 2000s by former RNZN hydrographic vessel HMNZS Resolution.