Navy Diving Team and HMNZS MANAWANUI in Tongan shipwreck search
The Royal New Zealand Navy (RNZN) Diving and Underwater Search Team, in a combined operation with teams from the Tonga Defence Force and Royal Australian Navy Clearance Diving Team, have located what appears to be the sunken vessel PRINCESS ASHIKA.
Using a Navy REMUS sonar system operating from the Tongan Defence Services Vessel VOEA PANGAI, the team detected a vessel which fits the general size and shape of the missing vessel PRINCESS ASHIKA.
Image Right: Navy divers preparing the ROV in Tonga (MC 09-0266-027).
The inter-island ferry is believed to have been carrying over 150 people when it sank on Wednesday night, 5 August. Fifty-four people were rescued, two bodies have been found but possibly about 100 passengers remain unaccounted for, believed drowned. The PRINCESS ASHIKA was sailing from Nuku'alofa to Ha'afeva, in the Nomuka Islands group, when it sank, after issuing a mayday call, about 86km northeast of the capital.
An RNZAF Orion took part in the initial searches for survivors, along with local vessels. Despite the intensive aerial and surface search over the 3-1/2 days, there was no further sign of survivors from the ferry.
The RNZN team, and an Australian Navy diving team, both arrived in Tonga during the night of 7-8 August. The next day the teams conducted a survey of the recovery site using an underwater search vessel. It took until 12 August to locate the PRINCESS ASHIKA.
The sunken vessel is located 11 nautical miles south southwest of Nomuka in the Ha’apai Group of islands; it appears to be intact, in an upright position, but is at a depth of 110 meters.
However the RAN and RNZN Divers do not have the capability to conduct recovery operations beyond 50 metres depth. Lieutenant Commander Andrew McMillan, Commanding Officer of the RNZN Operational Diving Team, said “The RNZN Diving and Underwater Search Teams were pleased to have been able to find the location of what appear to be the PRINCESS ASHIKA; however we are sad that due to the depth of the vessel this will not lead to closure for the Tongan people. Our hearts and sincere condolences go the families of the victims of this tragedy”.
Image Left: REMUS image of PRINCESS ASHIKA on seabed - note bow section with ramp, bridge area and passenger compartment. Large balls are very large rock spheres. Depth is 110 metres. (MC 09-0274-002).
Saturday 8 August, 2009 - MANAWANUI to join search
The Diving Support ship HMNZS MANAWANUI sailed for Tonga on 8 August, to help in the search operation, following the sinking of the ferry. The MANAWANUI is due to arrive in Nuku’alofa on the morning of Saturday 15 August, and will allow the Navy Diving Team to conduct further reconnaissance operations on the PRINCESS ASHIKA using a remotely operated vehicle (ROV). The ROV will provide images that will give 100% certainty to the identity of the sunken vessel and will be used to conduct an examination, explore the wreck site, map the debris area and allow the diving teams to examine what further options are available.
Tuesday 18 August, 2009
At 08:00 am this morning (local time) the Remote Operating Vehicle (ROV) operating from the Royal New Zealand Navy Diving Tender, HMNZS MANAWANUI, has allowed formal identification to be made of the sunken vessel resting on the seabed as the PRINCESS ASHIKA. The ROV identified the vessel by allowing the Royal New Zealand Navy’s (RNZN) Diving and Underwater Search Team to read the ship's name plate. Conditions on the surface are not currently favourable but the Navy team is continuing with its efforts. The water clarity is reported to be very good and this has allowed the team to conduct a thorough search of the sunken vessel.
One side of the PRINCESS ASHIKA is obstructed and the ROV is unable to see into the passenger compartment. The vessel is sitting flat on the seabed and appears to be intact. No images of the vessel from the ROV are currently available. The ROV has been able to enter the cargo hold and is providing information to the Transport Accident Investigation Commission investigator. The Navy team onboard MANAWANUI is continuing with its operations and hopes to return to Nuka’alofa tomorrow as planned.
The Commanding Officer on site, Lieutenant Commander Andrew McMillan, says, "Although the team are very happy to have formally identified PRINCESS ASHIKA, they are frustrated and disappointed at not being able to provide any further information that may bring closure to the Tongan people".
What is the Remote Operating Vehicle (ROV)?
The RNZN currently utilises the Sea Eye Falcon Remote Operated Vehicle (ROV) and it is best described as a tethered mini submersible. Being remotely operated they are connected to, and controlled from, the surface. The ROV is attached by an umbilical cord through which the pilot sends control orders via joystick to the various propeller thrusters that allow it to hover, turn, descend and rise under power. The RNZN ROV has small sonar in the nose that can ping out looking for things, like a sunken ship, and the pilot with his control box can look at echo returns on his screen. It also has a video camera in the nose which is invaluable for identifying/confirming what the target is they are looking at. The Falcon is very portable and as long as there is Single phase 100-270 V input it can be operated almost anywhere. Among the many features the ROV has includes a 300 metre depth rating with a 16 kilo payload, high resolution colour camera on 180 deg tilt platform, variable intensity 150 watts of lighting and a portable surface control system with video overlay and daylight readable display.