Chris Davies
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The cramped sleeping arrangements on HMS Triumph

30 July 2012 Last updated at 08:00 BST

Able Seaman Chris Davies shows the confined living quarters aboard HMS Triumph with some crew having to share bunks no bigger than a coffin.

HMS Triumph is one of the Royal Navy's Trafalgar class submarines, using its stealth on counter-piracy, anti-terrorism and narcotics operations.

For the crew of 120 on HMS Triumph it has been an endurance challenge.