Feature 4 | SUBMARINE RESCUE


IFE designed to increase submarine safety margin


James Fisher Defence has developed a submarine Inflatable Freeboard Extender (IFE) designed to improve safety during surface abandonment in poor weather by preventing sea water ingress through the boat’s hatches.


E


mpirical evidence and modelling suggest that a significant number of submarine emergencies will


occur on the surface. Such events may lead to an untenable situation where the boat is at risk of sinking and the crew is forced into an evacuation situation. In a high sea state, with water washing


over the casing, this may deny the use of all the available emergency escape routes other than through the fin, thereby constraining the safe and controlled evacuation of the submarine. To address this shortcoming, James


Fisher Defence has designed an Inflatable Freeboard Extender (IFE) device to raise the useable freeboard by 1m so as to enable the use of all rescue hatches to affect the rapid escape from a distressed submarine in high sea states. The IFE serves to increase evacuee


safety whilst preventing flooding of the submarine through the open hatches. With the


system fitted, all rescue


hatches can be utilised, even in adverse weather conditions, making mustering on the casing and entry into the water a far safer procedure than with existing systems. Pre-production systems have been successfully tested on both Royal Navy and French Navy nuclear- powered submarines. Two variants have been engineered by


the company: an internal IFE designed to be temporarily fitted to the inside of the submarine escape trunk in the event of surface abandonment in high seas; and an external IFE option intended as a permanent reusable escape option fitted between the rescue seat and the escape hatch of a submarine. Te internal IFE system installs into a


submarine’s escape trunk coaming when required. Once in position below the escape hatch, the IFE is locked in place


Warship Technology March 2011 23


and water sealed by inflating the sealing bladder located around the fixed ring. Controls for the bladder are located next to the liſting handle, allowing them to be operated by thumb while the hand is still gripping the liſting handle. Once locked in place the escape


hatch is remotely opened and the IFE can then be deployed by opening a single valve. Te IFE inflation system is automatically staged to inflate the skirt and support ring sections first and then the tower section. High-pressure air used for inflation can be taken directly


The internal version of the IFE is designed as a permanent fit. It would provide a ‘safe haven’, protected from waves, where rescuees can await rescue in safety (Credit: James Fisher).


The external IFE provides a temporary means of extending the submarine


freeboard to improve safety during an evacuation (Credit: James Fisher).


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