Britain’s special forces to get Bond-worthy mini-sub

Very interesting article in today’s Sunday Times

The ‘shallow water combat submersible’ is a lightweight mini sub with sonar sensors to detect and evade enemy pre-landing

The combat divers of Britain’s Special Boat Service (SBS) will soon be getting some new transport. The “shallow water combat submersible” (SWCS) will be able to carry six frogmen for 100 miles at depths of up to 300ft. Studded with sonar sensors, the lightweight mini-sub is designed to detect and evade an enemy, before landing special forces under its nose.


It is surely no coincidence that the development of the 30ft submersible is being fast-tracked just as maritime piracy rears its head again. Brought to a war zone by a larger submarine, a surface vessel or even an aircraft, the stealth-equipped mini-sub will take specialists in reconnaissance, assassination or demolition close to a hostile coast or vessel. It is being designed for America’s equivalent of the SBS, the Navy Seals.

The new mini-sub will replace the Seals’ and the SBS’s US-made “swimmer delivery system”, known as the Mk VIII boat. The 22ft, electrically powered Mk VIII is ridden by a crew exposed to the sea and owes a design debt to the midget submarines developed by Britain and Japan during the second world war. Sadly, its electronics are nearly as old, dating back to its conception in the mid-1970s.

Its replacement, which will also doubtless be shared by the two forces, also “runs wet” — that is, floods with water once launched, saving the trouble of fitting an airlock. It will benefit from recent developments in electronic warfare, possessing a miniaturised Doppler sonar, the sonic equivalent of radar, able to provide a three-dimensional image of the sub’s surroundings. Coupled with data provided by motion sensors, it will allow the boat’s powerful computers to navigate underwater in zero visibility and with unprecedented accuracy, without the need to surface to obtain visual references or a sat nav fix.

Unlike the Mk VIII, the submersible will have the ability to raise a periscope — but this won’t be an old-school optical version. Instead it will use video imaging technology. Before the main part of this sensor mast even breaks the surface, a whisker-like antenna attached to the top will poke above the waves and sniff for radar activity. If it detects an enemy sweep, the boat dives and moves somewhere safer before repeating the process.

Passive sonar sensors on the exterior and a sound-absorbing fibreglass hull help it to evade detection underwater, and battery-powered electric motors allow it to run almost silent.

The mini-sub will be equipped with a pair of smart, torpedo-like probes. Using side-scanning sonar, they can scout the waters on each side of the boat, returning either to the mini-sub or its host vessel at the end of a mission.

The stealthiest way of launching the mini-sub will be underwater, via another submarine. Like the Mk VIII boat, it will emerge from a dry deck station, an airtight cylinder that can be fitted onto a larger submarine in hours, or even dropped directly into the ocean from a cargo plane. Two such stations will be piggy-backed on the US Navy’s new SSGN boats — Ohio-class nuclear missile submarines that have been fitted for Seal operations.

“SSGNs are a brilliant idea,” says Lewis Page, defence correspondent for The Register, a technology news website. “The Navy had these four boats lying around after the Salt arms reduction talks made them redundant, so they stripped out their ballistic missiles and replaced them with 154 non-nuclear Tomahawk cruise missiles. This also left enough space to accommodate more than 100 Seal frogmen and mission specialists.”

The first underwater cruise missile launch from an SSGN took place last year, and a base is now being built for them in Diego Garcia, the British-controlled island in the Indian Ocean. This would put the boats within operational reach of Somalia, as well as Iran, where they could lurk offshore for months at a time, inserting and recovering Seals via mini-subs.

Britain, meanwhile, will be launching its first SBS stealth sub by 2013 from the Royal Navy’s latest Astute-class nuclear submarines, the first of which is expected to go into service this year.


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