Shortcomings in a two-man escape submarine procedure have been remedied by South African ingenuity and successfully tested onboard SAS ‘Manthatisi in False Bay.
The tower escape system allows for two submariners to exit a stricken submarine via the conning tower. The seamen, wearing special air-filled suits allowing a rapid ascent to the surface, climb the conning tower ladder and wait for the tower to be flooded. They then rise to the surface and the tower is refilled with air ready for the next pair of crew members.
“Shortcomings in this two-man escape procedure were discovered during trials after the Heroine Class Type 209 submarines were commissioned,” SA Navy spokesman Commander Greyling van den Berg said.
“As the tower floods, the bottom sailor is forced up by air in his suit causing both sailors to get stuck at the hatch opening.”
Recently a South African developed and produced prototype system which enhances the original system, was tested onboard SAS ‘Manthatisi.
“The successful test was conducted from a depth of 20 metres. Project TESS, an acronym for submarine tower escape safety system, was initiated by the SA Navy in 2009 in conjunction with Armscor, the Institute of Maritime Technology (IMT) and the Council for Scientific and Industrial Research (CSIR).
“The new system has a special mechanical rail system inside the tower. Each submariner hooks onto it one below the other. As the tower floods the rail system keeps the submariners in position, despite their air-filled suits.
“The submariners are released by an automated hold-trigger and release mechanism opening the tower upper hatch. This system works even if the submariners are unconscious.
“The entire procedure takes between three and ten seconds for two submariners to surface from a depth of 10 metres. The escape cycle is repeated until the entire crew has escaped,” he said.
The SA Military Health Service (SAMHS) Institute for Maritime Medicine was extensively involved in the planning phase and provided medical support during the test. This because of the risks associated with quick ascents, including barotrauma (decompression sickness), hypothermia and carbon monoxide poisoning. SA Navy divers were on hand to assist their below surface colleagues as they surfaced.
“It is envisaged TESS will eventually be incorporated on all SA Navy submarines. Successful completion of the system by aspirant submariners will be an additional requirement for qualification.
“The successful TESS test shows the SA Navy takes the safety of all its members seriously and goes to great lengths to ensure equipment, both sub-surface and surface platforms, can be operated safely.
“The False Bay test also confirms the SA Navy and its partners – Armscor, the IMT and the CSIR – are at the forefront of technology and engineering internationally, as South African submarines will be the first fitted with TESS,” Van den Berg said.