“The fundamental tenets of network-centric operations NCO0 have long been an integral part of the way navies do business. The network-centric construct that has increasingly seeped into all aspects of military doctrine – a construct characterised by the linking of sensors, decision-makers and weapon systems to deliver decisive effect – resembles traditional naval warfare in many ways. The need to operate in a joint environment and the increased sophistication of information, surveillance and reconnaissance (ISR) sensors has placed pressure on naval communications systems. This has become particularly important in submarine warfare with submarines operating in conjunction with surface vessels as their stealth characteristics are employed in a ISR role, developing improved persistent and robust communication lines for them is becoming more and more essential. In terms of submarine communications, water-penetrating masts are only part of the solution. These masts can cause a wake and a plume, as the submarine must move to maintain its depth, forcing the development of alternative communication systems. Testing has largely focused on ELF and VHF acoustic and laser communications solutions to address the ‘at speed and depth’ requirements, in particular the advantages of using tactical pagers, buoyant wire antennas and one – and two-way expendable optically tethered communication buoys.”