Inflatable freeboard extender (IFE)

The Inflatable freeboard extender (IFE) is an easy to operate, cost-effective and reliable escape system.

Designed to assist submariners needing to escape rapidly from a distressed submarine in high sea states, the IFE improves safety during abandonment in poor weather by preventing sea water ingress through the hatches.

No modification is required to the existing trunk or hatch opening to retro-fit the IFE, making it suitable for use across a wide range of existing submarine types.

All IFE options are inflated by the operation of a single valve on a panel outside the escape tower to enable fast and simple operation during pre-abandonment. Once inflated the tower forms a rigid freeboard structure sealing the escape hatch and preventing sea-water ingress.

The IFE is inflated either by air taken directly from the host submarine gas supply or via a separately stowed charged gas cylinder, enabling fast, even and controlled inflation of the IFE in a series of stages. Deflation is the reverse of this procedure and once fully deflated, the IFE secures itself in place ready for immediate re-use.

Inflatable freeboard extender (IFE) Inflatable freeboard extender (IFE)

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IFE 1 - Prod.JPG

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IFE 2 - Prod.JPG




  • Enables use of casing hatches in adverse conditions
  • Increases number of useable escape routes
  • Prevents water ingress during surface abandonment
  • Re-usable
  • Proven technology
  • Improves safety at sea

The externally fitted IFE is designed as a permanent, reusable escape option, fitted between the rescue seat and the escape hatch of a submarine.  Stored in a deflated state within a GRP housing, the external IFE is fitted beneath the lip of the rescue seat under the casing. When stowed for transit in normal use, the IFE is stored in a free-flooding compartment. The benefits over the internal IFE are that it inflates before opening the hatch, has a larger safe haven and is readily reusable.

The Internal IFE option is designed to be deployed, when required, to the inside of the submarine escape tower or casing escape hatch. Testing has confirmed that utilising the IFE will enable submariners to use a casing hatch, previously unusable in such circumstances, to escape from a submarine in a surface abandonment or emergency situation. An escape rate of 2-3 submariners a minute has been achieved during testing of IFE.  

Type Document Download
Flyer Inflatable freeboard extender (IFE)

IFE flyer R5