Significant Developments in Naval Technologies on Surface Ships

Stealth technology construction techniques result in a ship that is harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology

Issue: 1 / 2019By Commodore Samir Advani (Retd)Photo(s): By US Navy
US Navy’s newest and most technologically advanced warship, USS Zumwalt (DDG 1000)

The increasing complexities of operations in the maritime arena is throwing up fresh challenges as well as forcing the navies to have a relook at their doctrine and operational philosophy. With the increasing emphasis of Operations Other Than War (OOTW), wherein probability of direct naval combat between adversaries, is increasingly seen to be very low, the growing and often prohibitive cost of modern weapons; navies around the world have been forced to factor in varied and often conflicting demands (from platforms, equipment and personnel).

Technological Advancements Relevant to the Surface Navy

Few technologies which can play an important part in the modern maritime arena and provide new tools are listed below:

Stealth Ships. The US Navy inducted the USS Zumwalt, a “stealth” ship, in October 2016. It reflects the most advanced technology available for stealth ships and is currently the largest destroyer ever built. Despite being 40 per cent larger than an Arleigh Burke Class ship, the radar signature is more akin to a fishing boat. Present plans include building at least two more.

In designing a ship with reduced radar signature, the main concerns are radar beams originating from other warships or sea-skimming anti-ship missiles with active radar seekers. Therefore, the shape of the ship avoids vertical surfaces. Other techniques to reduce reflections are elimination of cavities and round surfaces such as turrets and funnels. The hull shapes include tumblehome hull designs which slope inward from the waterline, and Small Waterplane Area Twin Hulls (SWATH) hulls which allow for better stability when using a tumblehome hull. These Radar Cross-Section (RCS) design principles were developed by several navies independently in the 1980s using work done on aircraft RCS reduction as the starting point.

Stealth technology construction techniques result in a ship that is harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction (Acoustic quieting) are unique to stealth ships’ design. Though RCS reduction is a fairly new concept, many other forms of masking a ship have existed for centuries or even millennia.

Littoral Combat Ships and Multi-hulls. A trimaran (or double-outrigger) is a multihull boat that comprises a main hull and two smaller outrigger hulls (or “floats”) which are attached to the main hull with lateral beams. Most trimarans are sailing yachts designed for recreation or racing; however, newer materials allow them to be larger ships capable of being used as ferries or even warships.

In August 1998, the UK Ministry of Defence (MoD) awarded a contract to Vosper Thornycroft to construct a trimaran hull, Research Vessel (RV) Triton. She was launched in May 2000 and delivered in August 2000. Triton then began a two-year risk reduction trials programme for the UK MoD and the US Department of Defence.

In October 2005, the United States Navy, based on Austal’s experience, commissioned for evaluation the construction of a General Dynamics LCS trimaran designed and built by Austal — the Independence. GD functioned as the ship systems integrator, and is responsible for the design, integration and testing of the ship’s electronic systems including the combat system, networks, and sea frame control, while the hull was built by Austal.

The integrated electric propulsion technology is an arrangement wherein gas turbines or diesel generators or both generate three-phase electricity which can be used to power electric motors which turns propellers or water jets

The Independence LCS, commissioned in January 2010, is an open ocean capable vessel but is designed to defeat growing littoral threats and provide access and dominance in the coastal water battle space. The trimaran construction is unique to the US Navy and lends the Independence variant some unique capabilities and sea-keeping characteristics. Its flight deck is the largest of any current US Navy surface combatant, and its hangar bay is able to hold two MH-60 helicopters. Up to six of these vessels are to be built subsequently.

Closer home, Survey ship INS Makar, the first indigenously-built catamaran hull vessel of the Indian Navy was commissioned in September 2012 and is in active service. One presumes that the effectiveness of the technology will be used as a basis for future warships.

Trimarans have a number of advantages over comparable monohulls (conventional, single-hulled sailboats). Given two boats of the same length, the trimaran has a shallower draft, a wider beam, less wetted area, and is able to fly more sail area. In addition, because of the righting moment provided by the wide beam, trimarans do not need the weighted keel that is required in monohulls. As a result of the wide beam, the trimaran offers much better straight-line performance than a mono-hull, is able to sail in shallower water and for sailing vessel to maintain its stability in stronger winds.

Integrated Electric Propulsion

The integrated electric propulsion technology is an arrangement wherein gas turbines or diesel generators or both generate threephase electricity which can be used to power electric motors which turns propellers or water jets. The system uses electric transmission instead of mechanical transmission which eliminates the need for clutches and reduces or eliminates the use of gearboxes.

Some of the advantages of using this technology are freedom of placement of engine, less noisy ships, reduction in weight and volume etc. Warships like HMS Queen Elizabeth of Royal Navy and Zumwalt Class Destroyers of US Navy use the integrated electric propulsion.

Unmanned Surface Vessels. The last decade has seen a flurry of activity in unmanned aerial vehicles and in turn with advanced navigation abilities the growth of Unmanned or Autonomous Underwater Vehicles. Unmanned Surface Vessels (USV) however, were not given the necessary push. But, just as Air Forces have taken to UAVs, the next stage will be when naval forces resort to wider use of USVs to meet their surveillance needs, and in turn for some offensive tasks. The roles could range from anti-terrorism patrols, surface attack, force protection, MCM, discrete surveillance (read EW patrols), and even shallow water ASW tasks. The USV can either be controlled from shore for coastal protection or from a ship giving the fleet an added flexibility and reach at a fraction of a cost of an air asset. Further it also removes the man from the vicinity of action, thereby providing an unmanned element to be sent on hazardous missions. To ensure a ‘man in the loop’ concerns that understandably arise, the use of data and video links allow Commanders to give executive decisions similar to that used by contemporary UAVs. Therefore, the game changer in this field has been (a) the ‘drone’ like onboard systems controlling navigation and on-board systems, and (b) mission command and control systems. These two are integrated with conventional surface ship systems and some armament. The main advantage is of course the ability to lower costs, near-continuous deployment even in adverse conditions and safety in hazardous situations. Rafael’s ‘Protector’ is one such operational USV being used extensively for patrolling and Force Protection duties in Navies as widely separated as Latin America and the Far East.

Infra-Red Search and Track. Modern surface navy warfare has depended on radars to extend the detection horizon to beyond line of sight limits. However, this comes with the disadvantage of the enemy also being aware of your presence as soon as he detects transmissions radiating out in all directions, including upwards. The advantage in the initial detection therefore appears to be with the airborne platform. Countering low-flying, small RCS anti-ship missiles is also one of the major challenges that the radar is trying to cope with. One of the possible solutions is the use of Infra-Red Search and Track (IRST) technology that could to a degree alleviate the false alarms that arise from use of radars this could be a great asset in providing an all-round situational awareness, 24X7 without any active transmission. In addition, when a strict emission control policy is in force, the IRST would be able to provide better surveillance than the human eye. Previous generations of IR systems were plagued with two main lacunae (a) multiple false alarms, and (b) how to cope with multiple targets. When in passive the detection is dependent only on the IR signature of the target, thus providing for a very high probability of detection. Advanced signal processing techniques ensure a very low FAR. These systems are enhancers in Humanitarian Assistance and Disaster Relief (HADR) and SAR missions as well.

Short Range Surface to Surface Missile. The spiralling and prohibitive cost of a conventional Anti-Ship Missiles to be used in OOTW, an environment in which ships mostly operate, makes it very difficult to engage a missile worthy target in a cost-effective manner. At the same time, guns have a limited range, and result in exposing the warship to man portable or remote missiles such as RPGs or SAM-7s. A viable alternative is fitting ships with a lightweight, very accurate EO Missile having a ‘Man in the Loop’, with a reasonable range (about 25 km or so to provide standoff capability), which can incapacitate the target. These can easily be mounted on small vessels including smaller patrol craft and light helicopters to provide the commander an unmatched operational flexibility. This could be a very effective weapon in all facets and intensity of maritime operations. Rafael and MBDA already have such a missile in their portfolio of naval weapons.

Active Decoys. The next generation decoys, for use by surface combatants and submarines will have an active element to increase the effectiveness of the decoys and multiply the chances of survival of the platform manifold. An active torpedo decoy like Rafael’s ‘Torbuster’ can seduce and neutralise the torpedo during its run, thereby eliminating the requirement of firing multiple decoys and disabling the torpedo threat in one go. Whereas, against missiles an active off board decoy launched by ships provides for a better alternative than conventional chaff.

EM Railgun. The railgun is a device that uses electromagnetic force to launch high velocity projectiles, by means of a sliding armature that is accelerated along a pair of conductive rails. While explosive-powered military guns cannot readily achieve a muzzle velocity of more than about 2 km/s, railguns can readily exceed 3 km/s. For a similar projectile, the range of railguns may exceed that of conventional guns. Ranges also would accordingly be enhanced.

Railguns rely on the high speed of the projectile to inflict the necessary damage rather than the use of explosives. The weapon therefore is used to impart a very high kinetic energy to a projectile (e.g. Armour-piercing Fin-stabilized Discarding Sabot) rather than using conventional propellants. The destructive force of a projectile depends on its kinetic energy at the point of impact and due to the potentially large velocity of a railgun launched projectile their destructive force may be much greater than conventionally launched projectiles of the same size. The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry and the corresponding reduction in wear and tear of the gun, come as additional advantages.