Zumwalt class destroyer may be all awesome, but it is too expensive. Even more worryingly, it cannot fire its main gun because ammunition is too expensive. In fact, for quite some time modern militaries have been running into issues of ammunition being too expensive to achieve full effect before running out of it. Arleigh Burke class destroyer costs 2 billion USD, and fires 1,2 million USD missiles. But while destroying ships with those missiles is indeed a logical decision, sometimes sheaper options are necessary. Going back to Zumwalt, each LRLAP round costs 800.000 USD, compared to 1.600 to 2.200 USD for unguided 5 inch shells. Thus, increasing back-end system cost in exchange for cheaper ammunition might be the way to go.

However, if rail guns – or coil guns – do replace normal artillery, they may signal the return of a big-gun warships. Railgun ammunition would be cheap, long-ranged and invulnerable to either pont defences or electronic countermeasures. And because railguns are electromagnetic weapons, all-gun warship would have no dangerous explosive substances onboard. Railgun could reach range of 100 miles with Mach 7 projectiles. One problem is power – 25 megawatts is required to fire it, but Zumwalt can generate 78 MW of power. However, barrel would only be good for about a 1.000 shots, and it seems each projectile might cost 50.000 USD for… reasons.

If railgun proves practical, end result might be return of two old capital ship types (albeit I’m changing definitions here). One would be battleship, mounting rail gun or two, and shooting enemy full of holes with kinetic penetrators. Second would be battlecruiser, in essence a missile silo ship, with no guns (or one with chemically-propelled projectiles at most), but lots and lots of vertical launch missile tubes. In this situation, battlecruiser would likely take over antiship role, as range and flight time of railgun projectiles make hitting ships all but impossible at their maximum range, despite low CEP of five meters being expected. At 2.520 meters per second and range of 200 miles, flight time would be 127 seconds, or two minutes, allowing a ship at 30 knots to cover nearly two kilometers. That being said, some projectiles might be guided – but those would be fairly expensive.

Battleship and battlecruiser alike would need to be equipped with UAV – or datalinked to UAV from a carrier – in order to provide targeting against targets well below the radar horizon. Both ships would also need to be equipped with extensive self-defense systems, be it torpedo defenses or missile defenses. Alternatively, battleship could mount both turret and missiles, albeit at suffering risk of blowing up if hit due to all the explosives packed in. That would, however, allow it to be mostly self-escortable.

While railgun, due to already mentioned issues, would not allow a return of big-gun battleship as a ruler of the seas (that place has passed to submarine long ago), it would give considerable capability in gun support for ground troops. Against immobile shore targets, long flight time of the projectile would not matter, while extended range combined with large volume of fire would allow for destruction of enemy installations on shore and deep inland alike.

Arsenal ship on the other hand might serve in battleship’s second role of World War II: carrier escort. Equipped with large number of missile tubes and CIWS mounts, such a ship would be capable of attacking enemy ships, shooting down aircraft and intercepting missiles.

While heavy armour may not help much in terms of operational survivability due to modern ships’ reliance on easily destroyed sensory systems, battleship could have considerable armour for its most vulnerable systems. Even if the ship is disabled, armour could reduce casualties. And one fact often forgotten is that armour does not, in fact, need to be capable of stopping penetration to significantly enhance survivability. Even if weapon can penetrate armour at perfect angle, it may not penetrate at oblique angle. Internal armour will also help in compartmentilizing the damage. Another factor are near-misses: a missile that had been destroyed by CIWS can still cause extreme damage if wreckage hits a thin-skinned ship, as can anti-radiation missile homing in on ship’s radar. A torpedo exploding close to the ship can likewise cause damage. All that damage would be significantly mitigated by armoured protection.

Of course, an elephant in the room remains: is it truly smart to place in so much combat capability in one ship? If one was to ask US Navy, looking at Nimitz-class supercarriers, answer would definitely be “yes”. But much like many questions, actual answer depends on the context. One good thing however is that Iowa class battleships are all preserved as museum ships and could – in theory, and with a lot of time and money – be put back into service. But even then they would likely be merely a stopgap solution. However, regardless if newly built or old Iowas, battleships would have a strategic significance not easily ignored. High explosives have a way of solving problems, and in any case new battleships could be the size of HMS Dreadnought or Zumwalt class destroyer, not necessarily Iowa-sized.

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