Hydrographers kept busy in Vanuatu

This article has photo gallery Published on LCDR Alistair Tomlinson (author), ABIS Tom Gibson (photographer)

The Deployable Geospatial Support team, embarked in HMAS Tobruk, survey a potential anchorage during Operation Pacific Assist 2015. (photo: ABIS Tom Gibson)
The Deployable Geospatial Support team, embarked in HMAS Tobruk, survey a potential anchorage during Operation Pacific Assist 2015.

Hydrographers on HMAS Tobruk from the Deployable Geospatial Support Team have performed a vital role surveying potential anchorages and beach landing sites during Operation PACIFIC ASSIST 2015.

The operation has been the Australian Defence Force’s contribution to the assistance mission to Vanuatu, following Tropical Cyclone Pam which struck over 13-14 March.

Tobruk’s humanitarian assistance was focused on the islands of Tanna and Erramango, following a request by the Vanuatu National Damage Management Office for the ship to concentrate relief efforts at the remote southern province of Tafea.

Commanding Officer Tobruk Commander Leif Maxfield said operating at isolated locations was no barrier to the ship, as its amphibious capabilities were especially suitable for this kind of work.

The biggest obstacle the ship faced was a lack of information regarding suitable anchorages, as the only nautical maps of the islands were over 130 years old.  

“The surveys from the 1880s weren’t very useful because they were made using primitive lead lines surveys,” he said.

“The other complication is that Vanuatu’s volcanic topography results in the sea bed rapidly falling away at very steep gradients, making numerous locations unsuitable for anchoring.”

Commander Maxfield said that in these circumstances, the embarked hydrographers became indispensable as they worked to create up to date surveys for possible anchorages and beach landing sites.

“Before offloading humanitarian supplies for delivery via our landing craft, we need to be at anchor and have an identifiable route for getting them onshore and avoiding underwater obstacles like reefs,” he said.

Officer in Charge of the Deployable Geospatial Support Team, Lieutenant Commander Geoff Walker, said the hydrographers on Tobruk conducted over eight surveys during the deployment, primarily relying on a single beam echo sounder coupled with a global positioning system to record the sea bed depth.

“The process can take many hours as we methodically sweep for a suitable anchorage depth of 30 to 40 metres and a radius big enough to allow Tobruk a suitable swinging circle,” he said.  

“We also conducted a number of rapid environmental assessments for amphibious craft landing sites, which evaluate factors such as tides, currents, rocks, and beach gradient.”

Lieutenant Commander Walker said that the team was ideally suited to support humanitarian work, as the Pacific Ocean was full of small isolated islands, many of which lack basic information concerning suitable anchorages.

“While we hope that there will be no more cyclones, we will be ready once again to put our skills and training to maximum effect,” he said.