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Thursday 24 Aug 2017 | 01:31 | SYDNEY
Thursday 24 Aug 2017 | 01:31 | SYDNEY

Future Frigates and the wisdom of large surface ships

The USS Zumwalt in December 2015. Photo: US Navy.

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COMMENTS

2 December 2016 16:52

The first half of this year saw four major shipbuilding announcements: Austal winning fabrication of the Pacific Patrol Boats (SEA 3036), designers being selected for the Offshore Patrol Vessel (SEA 1180) and Future Frigate (SEA 5000), and DCNS winning Future Submarine (SEA 1000). Of these four, it was the submarine decision that attracted the most attention and commentary; this likely reflects both Australia’s fraught experience with the Collins Class and also SEA 1000’s absolute scale as our largest ever defence project (at least $50 billion across the life of the capability).

However, focus on the second-largest, SEA 5000 (some $35 billion of investment) will undoubtedly return, particularly as a final decision looms (slated for 2018). One topic that will almost certainly arise again played out across last year: whether building a capable fleet of large ships is a good idea, at least in comparison to more submarines. While this debate has several aspects, a key one is the survivability of the types of large, expensive vessels set to be procured by SEA 5000. Will they even be around long enough in a conflict to make them a sensible investment?

To address this in more detail, it is a fairly common-sense observation that to attack something, an aggressor needs first to find it, then successfully engage it with weapons. In turn, the defender’s survival formula is to firstly escape detection, and if engaged be able to defeat the attack.

Relating the aggressor’s position to the future naval environment, there appears to be a broad consensus that it will be both more surveilled and more deadly than ever before. There will be a proliferation of dispersed, networked sensors and advanced data processing, making all naval assets easier to find. Once found, they will be targeted by widely available long-range Anti-Access/Area-Denial (A2/AD) weapons including Anti-Ship Cruise Missiles (ASCM) and Anti-Ship Ballistic Missiles (ASBM). All this will see naval assets face overwhelming risk.

In response, for the defender, a common proposition is that submarines may be the only feasible vessels for contested environments, depending on their stealth to provide a good chance of survival. Surface ships, on the other hand, will become floating targets, and large surface ships in particular simply expensive follies.

Such analyses make the defender rely heavily on the ‘avoiding detection’ part of the formula. This bets the farm on future surveillance not outmatching submarines’ stealth, an uncertain prospect. A more prudent approach would consider the whole survival equation, thereby minimising reliance on any one part. From such a view, large surface ships appear to have distinct advantages due to the limited impact their size has on detection, and the substantial benefits it brings once under attack.

In terms of the sensors naval vessels will face, there are few where large size brings significant disadvantage. For radar, a target’s Radar Cross Section is less affected by size than shape and radar absorbing materials. Hence the United States Navy’s new Zumwalt Class ships, despite being substantially larger than their predecessors, are 50 times less radar-detectable than other destroyers. For passive sensors such as infrared, larger vessels have more room for the cooling systems and insulation to allow them to disappear more easily than smaller ones. Even when combating advanced techniques such as satellite-based wake detection, larger vessels have more room to house countermeasures, such as future wake suppression systems.

But if tomorrow’s environment is as surveilled as predicted, ultimately the ship will be found. And it is in precisely this situation that the larger vessel excels.

Ships have always been designed to fight battles and win. Today’s use Electronic Warfare (EW) suites to jam sensors and weapons, defensive missiles and guns to intercept threats, and ultimately armour protection when all else fails.

Smaller ships have less space and weight available for their EW systems and magazines of defensive weapons, let alone for armour. Once found, they can be overwhelmed with comparatively limited investment, thereby broadening the number of adversaries with the means to threaten them.

The exact opposite applies to larger surface vessels. Their size provides for more powerful and effective EW; their defensive magazines are bigger (including, in the near future, anti-torpedo torpedoes); and they are better able withstand being hit. Hence, once found, a large ship’s survival prospects are substantially better than those of a smaller one.

Further, large vessels’ advantages may increase dramatically with the rapidly maturing technologies of rail guns and lasers, due to their very deep magazines and comparative cheapness. Guided rail gun projectiles, of which large vessels could carry hundreds, have an estimated cost of some $25,000 per round (noting today’s Harpoon ASCM costs around $1,200,000). Likewise electrical lasers have effectively infinite magazines and costs-per-shot of around $1. The key requirement for such weapons is a large, enduring supply of electrical power. Bigger ships can provide this with their substantial fuel stores in combination with electric propulsion or spare hull volume for generators; smaller ones cannot.

These developments would make defence against mass A2/AD attack not just feasible but affordable, thus complicating an adversary’s decision to even engage a large vessel. How many of their expensive, hard-to-replace missiles should they expend on a target that could well survive?

But what of the future for submarines? As I’ve written before, their dependence on stealth means they have much more to lose from surveilled oceans. Even if they maintain an advantage for some years, their decline seems likely. How will submarines fare, then, once their cloak is removed and they face attack, lacking powerful EW, defensive weapons and armour? The balance may well turn against them.

So, the folly of large surface ships and primacy of submarines is not clear-cut. Indeed, in pondering the future it’s worth considering the past, as the posited future A2/AD situation is analogous to the Cold War. Then, the Soviets planned massed attacks of missiles to defeat American carrier groups. The US Navy’s response, as the world’s most advanced and powerful navy, was not to abandon large surface ships. Instead it developed the Aegis Combat System, mounted in large cruisers and destroyers (including Australia’s AWDs), to fight through such attacks. And Aegis remains with us today.

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