SA subs lead the way

* SA Navy Diver Able Seaman Lindokuhle Ngidi signals everything is okay, while a relieved Petty Officer Eric Luvhengo agrees.

South African submarines will be the first in the world to be fitted with a new safety escape system, tested off Simon’s Town last month.

A South African-developed and produced prototype called TESS, an acronym for submarine Tower Escape Safety System, was initiated by the South African Navy in 2009 in conjunction with Armscor, the Institute of Maritime Technology and the Council for Scientific and Industrial Research (CSIR).

It was tested in the waters off Simon’s Town on Wednesday April 10.

Commander Greyling van den Berg, spokesperson for the SA Navy, said TESS would eventually be incorporated into all SA Navy submarines. Successful completion of the tower escape would also now be a requirement to qualify as a submariner.

“The successful test of the TESS shows that the SA Navy takes the safety of all its members very seriously, and would go to great lengths to ensure that our members can operate our equipment in a safe manner,” Commander Van den Berg said.

Most submarines are designed to let crew escape through various means, depending on the depth of the stricken sub.

If the submarine is lying in shallow water (with water entering the hull) the hatches are opened and the submariners can swim to the surface. Another route of escape, usually practised at a depth of about 100m, is the tower escape system.

Traditionally,this system allowed for two crew at a time to climb into the conning tower, wait for the tower to be flooded, then float to the surface.

The tower is then refilled with air, ready to release the next two submariners.

But, according to Commander Van den Berg, a flaw was found
in this procedure: the air inside the submariners’ specially designed suits that allows them to rise rapidly to the surface also forces the
crewman waiting at the bottom
of the flooded conning tower to float upwards past his shipmate so that they both get stuck at the hatch.

Recently though, a South African-developed and produced a prototype system, which enhances the originally fitted system, was tested on board the SA Navy submarine, SAS Manthatisi from a depth of 20m. The tests were dubbed Project TESS.

The new system sees a special mechanical rail system fitted on the inside of the tower. Each submariner hooks on to this rail system, one below the other.

As the tower floods, the rail system keeps the submariners fixed in position, despite the air in their suits.

This allows the submariners to be released by means of a hold-trigger and release mechanism which is automated, when they open the tower’s upper hatch.

Another advantage to this is that the system works even if the submariners are unconscious.

Commander Van den Berg said the entire procedure took about three to ten seconds for both submariners to surface, at a depth of 10m.

The escape cycle is then repeated until such time as all the crew have escaped.

Commander Van den Berg said that the SA Military Health Service Institute for Maritime Medicine was part of the planning, and provided medical support as quick ascents could cause decompression sickness, commonly known as the bends; hypothermia or carbon monoxide poisoning.

During the trial for TESS in Simon’s Town, SA Navy divers were close at hand to assist submariners as they reached the surface.