Republic of Singapore Navy (RSN) proposes code of conduct for underwater encounters

When submarines move beneath regional sea lanes - which are among the most congested in the world - the crew better know what they are doing.

A collision with a surface vessel or undersea object, a submarine that is less than shipshape or an ill-trained crew could have tragic consequences.

The Republic of Singapore Navy (RSN) invests heavily in submarine training. Every submariner can, for example, find his way about the vessel and to essential equipment while blindfolded. The RSN has also introduced its own submarine rescue vessel, the Swift Rescue, which is on permanent standby to support 171 Squadron, the RSN's submarine unit.

You can get your house in order.

But the bigger unknown is whether other maritime users will know what to do to avoid colliding with a submarine.

With this in mind, the RSN has proposed a code of conduct that aims to promote safer underwater operations for naval forces with submarines and for ships at sea. This code would fill an essential void as there is presently no code of conduct for incidents at sea governing the underwater domain.

The RSN's Code for Unplanned Encounters at Sea or CUES seeks to give submariners a set of rules of the road to avoid collisions with other undersea vessels (like other subs or unmanned underwater vehicles) or surface ships. It was floated at the Submarine Operational Safety Conference held in South Korea from 29 May to 2 June this year.

CUES is an apt acronym and more than a paper exercise in naval red tape.

It builds on 20 years of RSN submarine operations in regional waters as well as the Singapore Navy's experience operating submarines in the Baltic, which is used by the RSN's submarine training detachment in Sweden.

The RSN's 20th year of submarine operations, which was celebrated last Friday (23 June), has provided the Navy with the depth and breadth of expertise needed to propose a code of conduct that is relevant, timely and practical.

The onus, then, is for regional navies to embrace the code.

If the code is adopted by the more than 10 regional navies who operate over 200 submarines, submariners would benefit from a common code of conduct that provides useful cues on how to safely steer when submerged vessels encounter one another.

More importantly, the code would provide surface ships - especially merchant ships and civilian vessels - with important cues on what to do when they spot red smoke flares fired from a submarine about to conduct an emergency surfacing. Such a procedure would see several hundred tonnes of submarine shoot to the surface in seconds. This aspect will strengthen maritime safety as civilian vessels do not have sonar and are therefore are unaware of what lurks beneath them.

The sea may seem vast.

But the risk of collision is not theoretical.

In February 2001, the United States Navy (USN) nuclear-powered submarine, USS Greeneville, collided with a Japanese fisheries training ship, Ehime Maru. The emergency ballast blow executed by the Greenville brought her to the surface suddenly and the Ehime Maru was struck by the submarine as she emerged from the ocean depths. Nine Japanese aboard Ehime Maru were killed when their ship sank after the collision.

The underwater CUES recommends that surfacing submarines release a red pyrotechnic like a smoke flare that would float on the surface as a warning to ships in the vicinity. This would give surface ships time to clear away from that patch of sea as CUES would spell out that the sudden appearance of a flare is a sign that a submarine is about to conduct an emergency surfacing.

And in January 2005, the USN sub, USS San Francisco, collided with an underwater sea mount while travelling at full speed. The boat was nearly lost with all hands. This incident underscores another aspect of the RSN's outreach to regional sub operators: The sharing of information, best practices and agreement on common standards for how subs are made and operated safely.

While information on sub movements is sensitive, the RSN holds the view that navies can still collaborate by sharing non-sensitive information that affects the safety of submerged navigation. This includes seismic activity (that could interfere with sonar), fishing activity and real-time movements of deep-water oil rigs and deep draft vessels like very large and ultra large crude carriers whose hulls project tens of metres below the waves.

To promote info sharing, the RSN has developed a Submarine Safety Information Portal at the Information Fusion Centre at Changi Naval Base to facilitate the sharing of "live" updates of ships at sea. This big picture is useful as it can be used to coordinate submarine rescue assets, especially vessels of opportunity identified beforehand that have the equipment that can assist with the rescue of submarines involved in accidents at sea.

In January 2005, the US Navy sub, USS San Francisco, collided with an underwater sea mount while travelling at full speed. The boat was nearly lost with all hands but managed to limp to the surface. This incident underscores how the sharing of information on vessels of opportunity can lead to safer underwater operations for navies that embrace CUES.

The sea lanes in the Malacca Strait and South China Sea are not only congested. These highways for maritime trade also traverse relatively shallow water, with the southern reaches of the South China Sea typically around 60m to 70m in depth.

What challenges do submariners face in shallow water?

Think of Changi Airport's iconic control tower, which stands 78m tall. The height from the bottom of the hull to the waterline - a measurement known as the draft - of a full laden Very Large Crude Carrier is about 20m. So an underwater submarine in the South China Sea has a distance of about two thirds of the height of the Changi Airport control tower to avoid colliding with the hull of deep draft vessels like tankers, container ships, ocean liners and even oil rigs. It is not a lot of room to manoeuvre.

Even on the surface, when ships can see one another visually or on radar, collisions have taken place in broad daylight. These perils are exacerbated after dark.

In Singapore waters, the number of tanker arrivals has charted a steady climb over the past five to 10 years, from approximately 21,000 tankers of all classes (oil, chemical, liquefied petroleum gas and liquefied natural gas) to 22,000 tankers in 2015. Not only are more tankers calling at our ports, such vessels are bigger in size and tonnage. Fully laden oil tankers are a hazard to submerged submarines because their massive size and cargo makes them hard to spot on sonar.

Add to this number the rise in deep draft vessels such as ocean liners (which can embark thousands of passengers) and oil rigs (whose legs can reach the seabed), as well as expectations that the regional submarine fleet will jump by 100 hulls to around 300 diesel-electric subs by 2020 and one can appreciate the urgency of efforts to promote safer underwater navigation.

In years to come, one can expect unmanned underwater vessels to also ply beneath the waves, adding a new challenge to submarine operations.

Congested sea lanes and shallow seas have not deterred regional navies from adding even more submarines to regional waters. The underwater space will get even busier as more subs patrol regional sea lanes.

These challenges underline the importance of an underwater code of conduct to enhance maritime safety for all sea users.