Underwater Technology: Submarine rescue to say goodbye to Remora? | ADM August 2013

The future of the RAN’s trouble-prone Remora submarine rescue vessel will be determined in the near future, with strong indications that its return to service is unlikely given the success to date of Navy’s current contractor-provided submarine escape and rescue capability.

The 16.5 tonne Remora sank in 140 metres of water about 40km north of Rottnest Island in December 2006 when one of the two cables connecting it to the mother ship snapped during preparations for

Exercise Black Carillon, a RAN submarine rescue exercise conducted in the Western Australian Exercise Area.

Two crew remained trapped in the Remora for 12 hours before it was lifted to 15 metres below the surface by the secondary cable, which broke in heavy seas after both men made their escape from the vehicle.

Remora then spent four months on the seabed before being recovered in an operation supervised by the US Navy’s Supervisor of Salvage and Diving, repaired in Vancouver by its Canadian manufacturer, and returned to Australia in August 2008.

While the capability gap left by Remora was quickly filled under contract to the Defence Material Organisation (DMO) by the internationally-proven submarine rescue system of UK company James Fisher Defence (JFD), the intention was to return Remora to service by late 2011 in order to achieve Operational Release in early 2012.

Fast forward, and the UK company remains under contract until November 2014 and Remora’s future now depends on the assessments made both by an RAN study and, more recently, by an independent review, the outcomes of which are being passed to government for decision.

“Remora has been repaired, it has gone through factory acceptance trials, but it hasn’t gone through its full operating range of depths which would be required to get full certification from the classification society,” Commodore Greg Sammut, director General Submarine Capability Navy Strategic Command, told ADM.

“Before incurring all of that expense we thought it prudent to really work out whether that was going to be worth the effort.

“We’ve got to the stage now where we’ve really demonstrated the viability of the system we have in place and the question becomes, is it value for money trying to fully resurrect Remora versus either continuing with what we have, or doing something different again.”

Longer-term, the structure of the RAN’s submarine rescue capability for many years will be determined under the aegis of Sea 1354 Phase 1; Submarine Escape Rescue and Abandonment System.

Costed at the lower end of a $300-$500 million band, the project is anticipated to receive first pass by the end of next year with a decision no later than 2016, and initial material release by 2017-18.

While this new capability must be viable for not only the six-strong Collins class but also for the larger Future Submarine fleet, neither CDRE Sammut nor Peter Horobin, a former submariner and now president of the Submarine Institute of Australia and director, Service Division and Asia-Pacific region of JFD, envisage any fundamental developments in the relevant technology.

CDRE Sammut envisages the future involving a refinement of the concepts currently in place, with easier integration of rescue systems on to vessels of opportunity using interface templates.

Upgrade path

For Horobin, enhancements are likely to centre on improvements in communications and command and control activities, including the replacement of the underwater telephones currently in use with the more advanced systems that are already available.

Meanwhile a dozen submarine rescue experts remain on permanent standby at JFD’s facility at Henderson near Fremantle, ready to respond within 12 hours to an event that hopefully will never occur.

The Henderson team furnishes the core operating personnel for a rescue capability made up of five subsystems – an LR5 rescue vehicle, its A-frame portable launch and recovery system (LARS), transfer-under-pressure units, decompression chambers, and a Scorpio remotely-operated intervention system.

While the Remora is powered and controlled from a mother ship via a 914-metre armoured electro-fibre optic umbilical and accommodates one operator/attendant and six survivors, the 22.5 tonne free-swimming LR5 can accommodate 16 survivors in addition to its normal submersible crew of pilot, co-pilot and systems operator.

Maximum rescue depth is 400 metres in a current of no more than 1.5 knots, with endurance of six to 10 hours and the claimed ability to mate with a disabled submarine at an angle of up to 60 degrees.

The complete system is one of only three in the world that are entirely air-transportable (by C-17, C-5 Galaxy or commercially by Antonov 124 and Boeing 747); the others being the Scotland-based NATO submarine rescue system (crewed by JFD on behalf of the UK, France and Norway) and the US Navy’s Submarine Rescue Diving and Recompression System.

Within 12 hours’ notice of the RAN’s concern for the safety of one of its submarines the rescue system should be ready to leave the Henderson facility on trucks for its point of embarkation, either port or airport, depending on where the distressed boat is located.

In conjunction with the contractor, a decision will already have been taken by Navy, which is responsible for overall command and control and medical support, including operation of the decompression chambers, on the choice of mother ship.

The contracted Defence Maritime Services (DMS) ships Seahorse Standard and Seahorse Spirit cover the areas off South Australia and West Australia where submarine post-docking trials and the majority of exercises are held.

For elsewhere, a commercial vessel of opportunity, known to have adequate deck space to embark the rescue system and sufficient deck strength to mount the three-tonne steel footings that provide the LARS-deck interface, will have been selected from a database maintained by JFD of suitable ships and their day-to-day whereabouts and availability.

In some cases, vessels of opportunity will be equipped with cranes capable of launching and recovering the LP5 in its cradle, in which case installation of the LARS handling system may not be necessary.

At the same time JFD will have initiated arrangements for up to a further 30 experts to fly to Australia from JFD operations worldwide, initially from Singapore where the company and ST Marine are providing a complete submarine rescue capability to the Republic of Singapore navy through to 2029.

“First off I’d want to get the crew of the Singapore rescue vehicle – about four people – from our Singapore mother ship Swift Rescue and fly them to the Australian mobilisation port,” said Horobin. “So, in the event that Swift Rescue was transiting to the rescue site in support of the Australian rescue, another operational crew would be close to the distressed submarine.

“I’ve got two pilots for LR5; they can only work for so long before needing rest, and the Singapore team would be my second watch.”

Implicit in rescue scenarios is the assumption that the submarine in difficulty will be disabled on the seabed within the relatively shallow waters of Australia’s continental shelf.

“We don’t normally get into discussions on the depth to which a submarine is rated,” CDRE Sammut said. “But when you start reaching the maximum depth of the LR5 you’re already over the edge of the Continental Shelf where you have a very fast roll-off. The difference between that and the crush depth of a submarine is a very small ribbon of water.”

Time can be saved by transporting the Scorpio remotely operated vehicle (ROV) to the incident scene ahead of the rescue gear mother ship. The ROV would then feed video of the distressed submarine and how it was lying back to its host vessel, and record data such as water temperature and current to assist in deciding on a suitable rescue strategy.

Scorpio is also able clear any debris from across the rescue hatch with its manipulator, as well as place a transponder for rapid and precise location by the LR5.

The ROV can also fit an underwater telephone and in some circumstance provide life support to the trapped crew while the rescue system is gearing up, placing items such as air treatment products and medical goods into the flooded rescue tower which is then drained by the crew to access the supplies.

After the LR5 has mated successfully with the submarine escape hatch, takes on board up 16 survivors, returns to the surface and is hoisted aboard the mother ship, its stern is positioned inside a universal deck reception chamber which accommodates four survivors or crew at a time.

These are then moved, still under pressure, by way of one-man transfer chambers which are wheeled to one of two eight-occupant Type B decompression chambers on loan from the Royal Navy.

This adds a considerable degree of complexity and time to an operation which with Remora simply involved the rescue vehicle being lowered on top of a 36-occupant RAN hyperbaric chamber to effect a direct transfer. Refurbishment of the RAN’s two large hyperbaric chambers will be completed by the end of this year but as yet no simple transfer process from the LR5 has been determined.

“We could wheel them in the same fashion to the 36-man chamber but that’s painfully slow, you could spend three hours unloading the 16 rescuees from the LR5 using that technique,” commented Horobin. “Everybody agrees we need a new transfer under pressure system so that we can decant everybody out of LR5 in one step. In a perfect world that would be a triage centre to determine whether or not individuals needed decompression, but you’ve got to have space and organisation to make that decision. We’re working on a solution to that problem as we speak.”

Some differentiation in treatment regimes is already possible with the two 36-occupant chambers, each of which can be divided into three compartments with different pressures.

While rescue is always the preferred option to save life from a distressed submarine, in circumstances such as during hostilities, or where survivors are unable to maintain the watertight integrity or atmosphere of the wreck, survivors have the ability to escape without external assistance.

“In those situations, it would be the crew that would make the decision to use the escape tower, and when,” CDRE Sammut said.

RAN submarines are fitted with a single escape tower enabling each survivor, one at a time, to escape from a depth of up to 180 metres. The escape system fitted to the Collins class is a refinement of principles which have been honed over the past 65 years by submarine-operating nations, principally the Royal Navy. Hooded escape suits for each survivor are provided with clean breathing air from dedicated air banks in the submarine during the flooding-up phase of the escape.

During this process, water is admitted into the escape tower at a very rapid rate, with pressure doubling every four seconds – the aim being to minimise time under pressure and so reduce the chance of decompression illness on reaching the surface.

The hood inflation system (HIS) ensures that the pressure inside the escaper’s hood is slightly higher than ambient sea pressure, thus maintaining the integrity of the suit and providing a “head-in-air” scenario, enabling the survivor to breath normally.

Once equalisation with the outside sea pressure has occurred, the upper hatch of the escape tower opens and the survivor is disconnected from the HIS, breathing normally from the air in his hood as the suit’s buoyancy takes him rapidly towards the surface – again, minimising time under pressure

Once on the surface, the survivor deploys a single-person life raft to increase chances of survival.

Pressurised escape training run by RAN and contractor personnel for both RAN and Singaporean submariners resumed in March 2011 in the 20 metre deep water column at HMAS Stirling after a gap of nearly three years caused by a contractual dispute with then-provider ASC. In the interim submariners received their pressurised escape training in Canada.

The submarine escape training facility at HMAS Stirling is the only one of its type in Southeast Asia, and several other regional navies are understood to be considering the possibility training there. This is likely to be welcomed by the RAN, offering as it does the opportunity to engage regionally and globally at an unclassified level.

Practice makes perfect

Keeping the 12 JFD submarine rescue specialists current and motivated involves six-weekly drills where the full rescue system is deployed to Cockburn Sound, LR5 is launched and a variety of scenarios is explored.

Full scale RAN-sponsored Black Carillon exercises take place annually to test RAN command, control and medical capabilities, and also to conduct the challenging launch and recovery procedures of the submarine rescue vehicle in open ocean conditions. The exercise usually involves transfer of personnel from a bottomed submarine, but this is not always essential.

Black Carillon 2012 saw target plates for LR5 placed on the sea floor at 130 and 380 metres, the first simultaneous deployment on separate mother ships of the LR5 and the Scorpio ROV, and the first mobilisation of the RN-Type B decompression chambers with the rescue suite.

“Although there was no submarine we were able to exercise all aspects of the rescue and the intervention system with those two plates and then run simulated survivors through the transfer-under-pressure and decompression systems,” Horobin said.

The shore phase of Black Carillon involved a large and complex medical exercise, including round-the-clock treatment scenarios and continuous manning by the RAN of the hyperbaric system.

Planning is already well under way for Black Carillon 2013. This will involve the Australian Defence Vessel Ocean Shield, whose large midships-mounted crane will be used in lieu of the LR5’s A-frame launch and recovery system.

This will be the first time since 1998 that the exercise will have been conducted anywhere but Western Australia, with the entire suite being transported to Sydney in a test of the logistic organisation’s ability to rapidly move a significant amount of materiel and personnel.

The two DMS-contracted vessels Seahorse Spirit and Seahorse Standard will be replaced as submarine rescue escape gear and rescue gear mother ships in 2015 and 2016 respectively by 83-metre and 93-metre vessels. The Dutch-based Damen Shipyards Group is building these in Vietnam.

Both vessels are being constructed as part of the Contractor Asset Acquisition Program (CAAP), a three-way agreement between Defence, the National Australia Bank, and DMS, and will be maintained and operated by DMS under the Fleet Maritime Services Contract of which the CAAP is part.

It would be surprising if the built-in benefits of the contractor-owned, contractor-operated model were not continued into Sea 1354.

“Companies such as JFD are international operators and that helps them to maintain currency in a very highly specialised capability. Of course the advantage there for us is we’re not carrying that overhead in our contracts and we can utilise their skills across the globe,” commented CDRE Sammut.