Return of the Battleship?

[Sea Skimmer]

Good point about the Harpoon's ability to maneuver, I forgot about that. There's a new advanced long-range anti-ship missile due to roll out later this year with a 200nm range, but I wonder why we didn't do it sooner? Or was the Harpoon's range fine for what we needed up until now?

500nm, LRASM is based off the JASSM-ER with a turbofan instead of turbojet engine as on JASSM and has various other mods for vastly extended range. JASSM actually uses the same turbojet as Harpoon, just has better wings and more fuel which already got you from 80nm to 200nm. The US did not field a long range SSM earlier because it considered the problem of acceptable targeting almost intractable with TASM, and all OTH targeting programs for TASM were terminated at the end of the cold war. Supersonic missiles have slightly less of a targeting problem, but remain vulnerable as ever to eating cruise ships and fishing boats instead of the target, and still can miss completely.

In reality the USN didn't even give a damn about SSM version of Harpoon post cold war, and ceased fitting it on some warships. Out to the horizon the high supersonic SM-2 missile is vastly superior, and when you consider the realtive height of the trackers on the ship vs the tallest mast on the enemy ship, that can be ~30nm on its own. For OTH attacks functionally a plane was needed as a scout, and thus the plane could carry the missiles in the first place. SLAM-ER gave the USN a missile capable of hitting a ship at 150nm stand off from the carrier plane, which could make a 350-400nm radius unrefueled strike prior to launching. HARM also provided a 80nm range option for crippling enemy warship radars, and arrived with supersonic speed. This was a serious reason why the US didnt really care about supersonic anti ship missiles. HARM was high supersonic and could cripple the enemy radar. If the enemy had no radar then he'd be in no real position to stop other weapons from sinking him, even if the HARM damage was limited to the upper works.

LRASM solves the OHT targeting problem by using the IIR imaging seeker from JASSM in addition to a radar to precisely identify specific types of enemy ship. So it can use some of its long range to search the target zone (TASM did this too) but unlike TASM it will not simply attack the first ship it finds once it reaches the magic 'seeker on' point of flight. This is technology which was simply not plausible before the 21st century. The Soviets designed some missiles such that they could pick out an aircraft carrier from a smaller warship, but NATO had deception jammers which could negate this limited feature. Also it had no real ability in the end to tell a merchant from a carrier, it was just a size bias thing.

LRASM also has an ESM sensor so it can actively avoid enemy warships and fighters prior to reaching the target area. This does reduce the effective range to something less then 500nm, but said range should still be considerable, and it makes it plausible to engage targets identified only by ESM bearing or other uncertain methods which simply would not work with any other existing missile. Also has an inflight datalink.

When Harpoon was new though back in the 1970s its 80nm range was very high, only a few monster Soviet missiles weighing as much as seven tons each outranged it. Styx, Starbright and the ilk had much less range. So in that respect the US was ahead of the curve for a time, Exocet for example had under half the range with rocket power. This was simply because the US could build affordable small turbojets, and nobody else really could at that point.

Soviet OTH targeting was basically intended to be solved by lavish use of money, such as those ocean radar satellites which had very limited service lives, a few months maximum, and large numbers of very high endurance Tu-95-142 patrol planes. Also some missiles types could share radar data in small groups, four in the case of P-700, but this also meant the concentration of the attack was dilluted out of hand as the missiles searched divergent flight paths. All of this was highly vulnerable to interception by carrier launched fighters and shipboard missiles. Which is why aircraft carriers made more damn sense in the first place, something the Soviets only politically accepted in the 1980s. in the end all Soviet thinking and designs were an attempt to get around the fact that political and industrial considerations ruled out building a fleet of aircraft carriers in the early cold war, and they then became obsessive about a flawed development path. This was hardly the only place were the Soviets spent themselves into a black hole of fail until they went bankrupt and imploded of course.

Presumably. TASM, IIRC, was up to 250nm.

About 250nm yes, though I have seen indications that this was only the 'effective' range and the actual flight distance could be greater when accounting for the terminal search zone which could be rather large.

The reason the range is going to be lower then that of the conventional land attack Tomahawk missile was several fold, (while the nuke one goes way further simply because the nuke is 1/5th the weight of the HE warhead. Basically normally a Tomahawk flies at about 10,000ft for a large portion of its flight, then drops down to treetop height. That was fine if it was flying over open ocean to reach the shoreline, and only then would encounter defenses. For naval missions it was to fly the entire mission low, and in fact gains altitude to conduct its radar search more effectively, before diving again. So that cruise at low level with a full load of fuel greatly increased fuel burn (missile speed also varies in all this). As well the guidance system with radar weighed more and ate more power then the land attack stuff.

This variable cruise height issue also affects other missiles, including just about every supersonic Soviet missile. The P-800 Oynx missile (export Yanhont) for example can only fly IIRC 120km on the deck. At altitude it actually flies faster, but can go 300km with only the final 50km or so conducted at wavetop height. Pretty big difference! The P-500/700 super missiles cruised as high as 10,000m for maximum range, and some missiles were simply incapable of low level flight. Others like Kingfisher had the capability added later.

[Thanas]

Thanks Skimmer, that is all very educational.

Was the high intercept possibility of those huge soviet anti-ship missiles the reason why the soviets went towards carrying that many anti-ship missiles, hoping they could saturate the carrier group with more missiles than the planes could intercept? Or was there another reason why virtually every soviet warship carried those huge anti-ship missiles?

Did this concept go out of the window when Aegis got introduced, or did the soviets ever find a way around the problems posed of the Aegis-capable ships being able to coordinate their anti-missile capabilities?

[Sea Skimmer]

By the end of the Cold War the Soviets believed a coordinated salvo of 120 P-700 missiles would be required to combat a single US carrier group! Launching such an attack was almost infeasible. In the air a regiment of bombers was seen as a viable attack, but only if it could reach its launching position without being blown out the sky. That was always very situational, though by the late 1980s the PVO had finally been shoehorned into providing MiG-31 escorts to these aircraft, providing a chance of bomber survival even if intercepted, but only close to the Soviet coast. Even then defeating the entire missile raid was very plausible. In effect the land based escort was a concession to the fact that the Soviet Navy was really oriented towards coastal and submarine bastion defense. It did not take commerce warfare seriously after its 1950s plan to build 560 diesel submarines was terminated. After all why care about it when nukes will blowup the ports?

The Soviets persisted with this missile approach because of shear inertia and an industrial system which was incapable of rapidly changing approaches, much as this plagued everything else they did. You can't shuffle factories around like you can cold hard cash. Never mind all the politics tied up in people in power of the industrial concerns fighting each other, this is a big factor in why Kirov ended up so freakish.

The whole concept never had any real merit, even a very small carrier with a dozen light strike fighters could put more weapons in the air and at longer range then a ship like Kirov. Though in fairness if not for the command role you could put way more P-700 missiles on a hull that big, but Kirov was the worsts most illogical coastal defense ship ever. You can't make shit like that up, but it was. The Soviets designed a dedicated large anti ship cruiser meanwhile which had 48 x P-700 missiles, but much less in the way of other systems.

One might notice that back in the day, the US and France and Britain all fielded large supersonic stand off missiles launched from bombers, Hound Dog, Blue Steel and the like, and the US additionally did for a time have large sea launched cruise missiles in the Regulus family. Ultimately all of these weapons retired because none of them were seen as viable, nor was any sort of direct evolutionary replacement. Instead Western missiles got smaller and better, ASALM (not fielded) kind of makes a lot of Soviet missiles look like overgrown trash. Mach 4.5 at 80,000ft altitude, mach 2.2 on the deck, range 300 miles... and it only weighed 2,700lb making it compatible with fighter type aircraft, as well as fitting in the Mk41 VLS system. Oh and it was to be AAW capable as well as anti ship. It was tested but not fielded because vast numbers of Tomahawk cruise missiles could be bought instead, and by that point Tomahawk was service ready. The AAW requirement had a super painful evolution to what is now SM-6, held back mainly by fire control issues.

In the early 1960s the situation was more reasonable, this being the era when the west did field its own big missiles, and just one eight missile salvo from an Echo class submarine had a significant probability of scoring at least one hit, and since that hit would be with a nuclear warhead it was judged good enough. However even that one hit became iffy rapidly, because the earlier Soviet heavy missiles , both sea and air launch required mid course guidance from the launch platform. This meant the launcher had to actively emit, warning of the attack. The Soviets could not make an inertial guidance system capable of putting the missile on target on its own prior to the P-700 series, the P-500 missile on Kiev and Slava class ships still needed a guidance radar until a late 1980s upgrade as did all versions of Shaddock. Said radar could and would be jammed by US carrier launched electronic countermeasure aircraft, potentially negating the entire attack without firing a shot. Said aircraft could also jam the missiles own radars, this remains a potent defensive capability, as no amount of home on jam is going to help the missile at that point.

As well the tracking radars could only handle two missiles at a time, meaning that the salvo would come in a series of closely spaced waves, making defense far more feasible then it might be if all the missiles arrived at once. they NEVER do with missiles like this, from anyone. Most of the big Soviet missiles had to be fired about three seconds apart, even after the removal of the salvo limitation. One exception to that would be the Kynda class cruisers, which had multiple tracking radars, but they were very focused designs, and very silly. Later ships did not have the space for multiple trackers, though the salvo intervals shrank as guidance improved.

Typhon was the original anti saturation system, and while it was probably unworkable because of excessive power throughput in the luneburg lense (it was borderline for catching on fire) it should have been writing on the wall for the Soviets. Particularly since the US did made said technology work for the Nike-Zeus program, though it was superseded by phased arrays.

NATO Sea Sparrow meanwhile gave even fairly small ships a significant probability to hard killing multiple supersonic missiles at altitude, the thing is very underrated in general, let alone what happens when given the ESSM missile today. Once improved to actual work even the 3T missiles had very high kill probabilities against anything that wasn't on the deck, and the only saving grace for the Soviets on that front was that the Vietnam War limited deployment of those ships. But it did not halt the rapid advancement of jamming and decoy countermeasures. Nor did it halt radical improvements in carrier aircraft turning into the E-2 and then the F-14 a few years later. AIM-152 would have, if not for the end of the cold war provided the F-14 with vastly expanded capabilities, as well as giving the F/A-18 the same sort of capabilities to deal with massed threats.

What AEGIS really counted for was negating the need for multiple escort vessels to be in position to fire, meaning that then even shifting to a low level attack, which by nature only a few ships of the formation would be able to engage, would not change the math to advantage of the attacker. It'd just kinda remain the same. Its phased array radar is also much more capable of low altitude searches, though good mechanical scanning systems can be excellent at this. AEGIS was also cheap and reliable enough, in relative terms, to be deployed on a large scale. However even for ships with simpler systems advances rapidly improved their ability to engage missile fire, the ultimate expression of that being the New Threat Upgrade program which is frankly still better then what most warships outside the US navy mounted for air defense until very recently.

AEGIS also did reduce the burden on carrier fighters to shoot down enemy missiles, making it easier to deploy fighters at long ranges to shoot down the enemy bombers. Killing the bombers requires that the fighters already be airborne, limiting the number that can partake in the battle. If the goal is only to kill missiles then the fighters would be mostly kept on deck and launched into battle, allowing most of them to partake, but providing almost no chance of intercepting enemy bombers. On the other hand, that only applies if you only have one carrier. Once you had two... or more, you end up with enough fighters to do both at once, as well as having much broader scope of AEW coverage. And nasty tricks like missile trap ships.

The Soviet response was to design missiles capable of much higher supersonic speed at low altitude, P-500 for example did only mach 1.6 on the deck, but this meant major reductions in range for anything but the most stupid big of missiles, ones too large for carriage in large numbers by aircraft, while surface ships had little chance of surviving to get within range, and coordinating multiple submarines remains incredibly difficult. The subs also had survivability problems while submerged. The Soviets really couldn't do anything but try to throw more missiles at the problem, but with such expensive launch platforms that didn't get them far. We now know for example that only two regiments of Tu-22M bombers were assigned to anti ship missions full time, NATO feared it could be four or five just in Europe, meaning that to an extent the threat was overrated anyway.

None of this really did a thing to solve the basic problem of the sea control exercised by carrier launched aircraft anyway. The carrier is simply superior, which is why the Soviets eventually gave in and attempted to build them... but while not cancelling anything else as a counterbalance, great plan commies. China meanwhile, while fond of designing missiles, has not blown all its loot on exotic launching platforms the way the USSR did, its only large ones for example are required to fit on the H-6 bomber... a design functionally from the 1940s if much updated. It has no SSGNs, and its surface ships look much like US one's, if somewhat downscaled in a quest to rapidly build up numbers. It is firmly committed to conventional air-sea power. Turns out shear willpower doesn't change physics, and the carrier remains Queen of the Seas.

In all reality carriers are far more threatened by singular threats then obvious honking big mass attacks. One nuclear attack submarine is the deadliest threat, and a single enemy plane might escape notice and even blunder right into visual range of a carrier when the carrier group is operating under emissions control. When you do a mass attack you can't avoid emissions, and then the carrier gets everything it has ready, ensuring heavy losses for the attacker even if they are successful.

[Sea Skimmer]

Since the avoid ended up very long, and unedited, and hell if I'm going to edit it, I will put this concluding thought here.

In all of the above, regardless of the exact details, nowhere do you find a place where a battleship solves anything. But often do you see numbers becoming important. Numbers of attackers, numbers of defenders, dispersion, times of arrival, that all counts. But focusing resources into a single platform does not make sense. Even if a battleship were defined as any damn thing someone wants, and a ship with 120 x P-700 missiles was built, it wouldn't solve a thing. Oh I suppose one could claim it solved coordination of the mass missile attack, but it'd be so expensive, so valuable that it would require its own protective force least it be sunk before it can fire, and then that has to be coordinated anyway.

So why large aircraft carriers, which are the most expensive discreet weapons systems ever created? Because they are only a means to an end, a means to launch fighter aircraft which can be very numerous, and which are most of the most flexible and powerful weapons possible in the modern age. Carriers only get better at operating more planes by getting bigger, so this provides a big incentive to build them big, but towards a goal of numbers. We still haven't had a war show was 21st century planes can really do when used without limits, and with targets actually worth it. But then that is supposed to be the point of a modern UN era military, deterrence. Working so far, though rather pathetically borderline in Europe right now.


One technology does exist which could change everything, the scramshell... problem is I have it on good word that this is almost certainly physically impossible and its only ever been proposed in the most vague terms a long time ago. Its also very question that even if it could work it'd work to the extreme degree required to make it plausible to actually replace the main missile battery of a modern warship. Even then I highly doubt anyone would go build a battleship, compared to just putting a pair of 8in guns on every escort. Number of hulls still counts. In fact it counts more the more you think weapons will be destructive.

[Korto]

Would it be worthwhile to build a ship around some huge railguns, as a specialist bombardment ship? Not as a battleship, but as a seaborne self-propelled artillery. Or would that be a lot of expense for too little use?

[Thanas]

Thanks skimmer, that was - as always - very educational.

[Captain Seafort]

Would it be worthwhile to build a ship around some huge railguns, as a specialist bombardment ship? Not as a battleship, but as a seaborne self-propelled artillery.

As long as you're within ten miles or so of the sea there's nothing better than a battleship for artillery support - they're mobile, they're invulnerable to anything field artillery can throw, and they can deliver far superior volume and weight of fire than anything short of a full division's artillery.

Or would that be a lot of expense for too little use?

This, of course, is the reason it won't be done.

[Eternal_Freedom]

Korto, what you're describing is essentially a monitor, a ship with battleship guns for bombardment roles. We (Britain) built a few with 16" and one with 18" guns in WW2 and IIRC they were moderately useful.

but as Seafort points out, once you get far enough inland you are reduced to using missiles launched by destroyers, so why not just use destroyers anyway?

[Captain Seafort]

but as Seafort points out, once you get far enough inland you are reduced to using missiles launched by destroyers, so why not just use destroyers anyway?

I never said anything about missiles - the problem with them is while they're great for hitting high-value targets, they're expensive, and therefore unsuitable for plastering large areas - you're better off using aircraft using iron or cluster bombs.

[Eternal_Freedom]

Sorry, I was referring you saying that battleships etc are great if you're within 10 miles of the coast.

[Simon_Jester]

As long as you're within ten miles or so of the sea there's nothing better than a battleship for artillery support - they're mobile, they're invulnerable to anything field artillery can throw, and they can deliver far superior volume and weight of fire than anything short of a full division's artillery.

Except they're not invulnerable to truck-launched antiship missiles, or shells with modern warheads, if you're talking about closing to within ten miles of land. Those are just as easy to deploy against your ship as WWII field artillery would be. And in terms of volume of fire you'd do better to mount MLRS batteries on a freighter deck or something.

The armor belt of a WWII battleship is simply not protection against modern guided weapons- it wasn't designed to be such protection in the first place. What it can do is make the ship relatively immune to large-caliber, medium-velocity artillery shells falling from long range. But antiship missiles hit harder than those shells did, and modern warheads can penetrate a lot more armor than those shells could.

but as Seafort points out, once you get far enough inland you are reduced to using missiles launched by destroyers, so why not just use destroyers anyway?

I never said anything about missiles - the problem with them is while they're great for hitting high-value targets, they're expensive, and therefore unsuitable for plastering large areas - you're better off using aircraft using iron or cluster bombs.

As guided munitions become more effective, the list of targets that need to be hit by "plastering large areas" shrinks. For example, in 1960 the only way to defeat an armored company by air attack was massive carpet bombing of the area it occupied. Now it's possible to fire a salvo of missiles that will independently spot, home in on, and blow up the tanks while largely ignoring everything else in the area.

Also, a missile can be used to deliver a cluster bomb attack just as well as an aircraft. The main catch is that firing one missile is more expensive than launching one aircraft sortie. So firing a missile is more expensive than dropping a bomb or lobbing a shell at the target. But on the other hand, there's no risk of losing the fifty million dollar plane that dropped that bomb... or the billion dollar warship that fired that shell.

Bring a warship within 10-20 miles of an enemy-held coastline, or fly your fighter plane over enemy-held air defenses, and your risk of losing it is significant.

[Sky Captain]

The armor belt of a WWII battleship is simply not protection against modern guided weapons- it wasn't designed to be such protection in the first place. What it can do is make the ship relatively immune to large-caliber, medium-velocity artillery shells falling from long range. But antiship missiles hit harder than those shells did, and modern warheads can penetrate a lot more armor than those shells could.

Are modern anti ship missiles actually fitted with armor piercing warheads? I thought since no modern warship have serious armor anti ship missiles simply come with big high explosive warhead to do as much damage as possible to ship and spray any unburned fuel everywhere to ignite large fire. Battleship armor belt would be of little use against missiles because missile likely would hit the superstructure or upper hull above the main armor belt. A missile likely would wreck radar set of the ship and essentially do a mission kill to any battleship even if there are no serious damage to main hull structure and fire is extinguished quickly.

[Simon_Jester]

They aren't always, but very very easily could be. But basically, there are antiship missiles that launch top attacks and would probably defeat battleship deck armor, there are freaking helicopter-launched antitank missiles that would probably go right through the belt or turret glacis... Even if most modern antiship missiles are not designed to penetrate a battleship's armor belt, the basic fact remains that all those thousands of tons of armor plate aren't really doing as much to protect the ship as an equal amount of tonnage devoted to modern anti-air warfare systems would.

[Sea Skimmer]

Lots of missiles have shaped charge warheads, some high divers and supersonics have true armor piercing heads, and the issue is irrelevant anyway because if anyone was actually concerned about non existent battleships they'd just swap the warheads on the missiles they already have. On some weapons you could reasonably do this in the field before firing even.

Also no battleship fully armored its hull structure making all of them vulnerable to breaking up from simple high caliber high explosive warheads if enough hit. Smash the ends and upper decks enough and the ship will literally fall apart. This was one of many reasons why heavy armor had to be abandon. It was predicated on low explosive yields and completely random hit placement. If your stern falls off its really going to cease to matter how well the citadel works. Of course an unarmored ship would sink long before this, but the unarmored ship would be much cheaper and a smaller target and much less vulnerable to under the keel explosions inducing whipping in the hull. Armor belts try to resist that, and then the hull cracks badly where stress is concentrated. An army with a naval flank could just lay two mines per kilometer of coastline using speed boats transported on trailers and nobody would risk a heavy ship anywhere near it. But much denser fields can be laid quickly without specialist assets. Then the minesweeping vessels and drones become the weak link.

You also have a pesky issue now that some nations have anti tank missiles with ranges as high as 25km which would be capable of targeting and penetrating specific points on the battleship, like the main battery turrets.

[Patroklos]

The advent of guided missiles compounded this (a single Arleigh Burke destroyer could have done the job of the 6 Japanese carriers at Pearl Harbor and have ammo left over)

I would love to see where you found that. DDG51 Flight Is and IIs carry a maximum of 8 dedicated ASM and while you can use the SM2 (and they could carry up to 90 SMs but since they share that space with Tomahawks, ESSMs and ASROCs they never will) in surface mode its designed to take out aircraft. It might mission kill a modern unarmored warship but any WWII armored vessel would shrug an SM2 off with ease. Flight IIAs are even worse, they have zero Harpoons.

This is because our surface warfare model is based on air assets, so our surface ships are designed accordingly.

The battleship as we know it is dead and burried, there is little reason to bring guns, rail or no, back to ship to ship combat at range. We might, however, be able to bring back certain rolls a battleship had such as ground support. People have mentioned extended range munitions that can be delivered accruately without needing the logistics of a carrier/air wing/pilot over the target. Tha LRLAP is the current iteration of this idea. You can shoot from a deep magazine from a small ship in relative safety way offshore.

The problem with this idea is that the cost of the shells do not make them a better option (the ERGM for instance was 20oK a pop) over current missles and F/18s that also brought far more flexibility to the fight. If we can get this number down to say 10K a shot then it has a much brighter future

[Borgholio]

I would love to see where you found that.

Well (and please correct me if I'm wrong), since the battleships were anchored and not at sea, you could use the land-attack tomahawks against them (since they're basically static targets). If that's the case, you could hit each BB with 3 or 4 missiles each and still have enough left over to target the oil dumps, drydocks, and some of the airfields too.

[Patroklos]

No, as there were 18 ships sunk or run aground. That includes five battleships. Nor are Tomahawks armed with warheads designed to pierce battleship armor but instead destroy buildings and equipment sometimes via direct hit but often via airburst or cluster munitions. Each Tomahawk has a warhead of around 1000lbs, the Japanese were using 1670lb, 550lb and 132lb bombs as well as torpedos (Tomahawks obvious don't have that capability) from over four hundred airplanes. All of these weapons (especially the torpedoes and 1670lb armor piercing bombs) were specifically designed to attack armored warships. Not only that the battleship in question were able to shrug off (relative to an unarmored target) a good number of these munitions as designed, it was the volume of fire that you couldn't replicate with your DDG51 (even packed only with TLAMs) that overwhelmed them in the end.

Of course those Tomahawks also require GPS or TERCOM/DSMAC data, so unless you intend to warp back a few dozen satillites or the entire spatial intelligence apparatus of the modern DoD all those Tomahawks will be sitting useless in their tubes.

[Borgholio]

No, as there were 18 ships sunk or run aground.

You are right, I was referring to the primary targets of the raid.

Nor are Tomahawks armed with warheads designed to pierce battleship armor

How many inches of steel could a Tomahawk penetrate? The Pennsylvania-class had 13" belt armor but the superstructure at least should be pretty vulnerable to a missile attack. If it was a Harpoon instead, it would plunge through the deck armor and do even more damage.

it was the volume of fire that you couldn't replicate with your DDG51

The volume of fire was necessary due to the unguided nature of the weapons. Even with 400 planes attacking, many of the BBs were only hit with one or two bombs. It was the torpedoes that did most of the damage and while a Tomahawk would not be able to replicate that kind of damage, would a BB still be able to shrug off three or four cruise missiles to the superstructure?

Of course those Tomahawks also require GPS or TERCOM/DSMAC data, so unless you intend to warp back a few dozen satillites or the entire spatial intelligence apparatus of the modern DoD all those Tomahawks will be sitting useless in their tubes.

I thought DSMAC could use digital photographs from any source, not just satellites? Would it not be possible to take a drone photograph of the harbor and use that as targeting data?

[Sea Skimmer]

The smaller Japanese bombs were not intended to attack armored ships, Japan only had HE and GP types for those calibers at the time. They were considered defense suppression weapons, with a 2:1 mix of HE and GP. The 800kg bombs meanwhile were shaved down 16in naval shells which suffered from a very high dud rate in action, having of course not been designed and built to be shaved down into bombs, something to the tune of 200kg had to be removed, then fins and shackles welded on pushing the weigh back up. Japanese had to do that because they had never planned for bombing attacks on armored ships prior to formulating the Oahu attack plan, and didn't have the time or resources to produce a large number of new heavy forged bombs. Later in the war they did produce such weapons in both GP and AP configurations, though use was very low due to the primary targets being aircraft carriers.

Anyway the Block IV Tomahawk has a two stage warhead with a shaped charge with a follow through penetrator made of much tougher steel then existed in WW2. Using the terminal bunt maneuver it probably could pierce the decks of the old US battleships with luck, and not hitting any other major objects like gun barrels or turret roofs. While the decks were fairly thick over the magazines of some US battleships, they were also made by quilting together many layers of thin plates. That gives low cumulative resistance, much to the demise of Arizona. Belt armor would certainly stop it, because of the face hardening even were it much thinner, but that isn't how an attack would be made, hell I'm not sure Tomahawk can fly low enough to hit a belt period. None of those ships had much armored freeboard left, they all badly needed added or bigger blisters.

Block IV also has the ability to use its optical seeker against ships at sea at least on certain subvariants, but I would be skeptical that this would work against densely packed anchored ships, you could sure try. The Japanese attack range was so low that a Tomahawk would be able to get to the target area without GPS or tercom. Modern INS drift simply wouldn't be all that high at 175nm, and with the missile being faster then any fighter of the day and faster then the allowed speed of US high angle control systems it could just make its high altitude cruise right to the target area.

The probably result of such an attack would be sort of like a dense carpet bombing of battleship row, probably not that far divorced from the results of the Japanese high level bombing attack alone. Everything else would be more or less intact.

A very silly Tomahawk proposal did have a torpedo, but it was for ASW with its own sonarbouys and computer to make it an expendable ASW aircraft in function. Harpoon with a Mk46 for anti ship was also put on paper at one time, the torpedo being about the same weight as the normal warhead but with the missile lengthened to hold it.

I thought DSMAC could use digital photographs from any source, not just satellites? Would it not be possible to take a drone photograph of the harbor and use that as targeting data?

You can scan any photograph you want into the computer and try to use it, satellite overheads a typical because they can get very good grazing angles of enemy territory prior to a war. The big problem is you want near infrared photos, so you need good weather conditions for the satellites. The little drones US destroyers typically have would certainly be able to overfly the harbor without being detected at night, but they wouldn't normally have a near IR camera fitted. FLIR on those things is typically medium wave IR. Also it would be iffy to control the drone via direct radio link at sufficient range, though putting the control system in a Seahawk isn't out of the question.