u/JMHSrowing

(Pictured is a 17 cm Kanone 18; Wikipedia as source)

The Washington Naval Treaty limited cruisers to 10,000 tons of displacement, which proved to be quite the challenge to balance with the maximum 8”/203mm armament and enough armor to defend them from such as well. Almost all other cruisers, many influenced by the later London Naval Treaties, were armed with a greater number of the considerably less powerful 6”/~152mm guns.

Could there though have potentially been a sweet spot in between?

For example the 17 cm Kanone 18 used a shell of approximately 150lbs (68kg) and could fire it at a range of 28 km. Not a perfect example as its muzzle velocity is higher than liked for a naval weapon but still. A shell of their weight and its charge should be considerably easier to load than an 8” gun, while each weapon would also be lighter. Each barrel would give a broadside of almost 1.5 times the weight of fire of an average 6” weapon, which should mean more penetration at range.

The USN had a 130lbs shell for its remarkably high rate of fire 6”/47 series of weapons, so with enough engineering it seems like a 150lbs shelled weapon should be able to shoot pretty quickly.

So to me at least it seems like a cannon of this type of caliber could have been used as a compromise weight saving measure. You could get a shell with the range and penetration enough to take on an 8” armed ships albeit with less boom per hit but in return you could use saved weight in say armor so your own ship could more comfortably survive enemy hits.

. . . Yes in theory there was the 180mm Kirov class of ships but the utter embarrassment that their weapons turned out being means the less said the better.

What do you all think?

Does the shell and weapon weights of the 6” and 8” just make them optimal?

Or did interwar designers miss an opportunity?

As the pictures suggest, I think that the biggest issues are that of patrol vessels and manned aviation.

The patrol vessel issue is pretty self explanatory, there is a pretty passing note that they will look into it but nothing concrete and the allocation of 200M Pounds isn't enough for replacement of even the Batch 1 River class which will be coming up decommissioning in only a few years. The role of ships like this not only can't be done by any drone, but they also seem like the type of vessels which could be used to leverage drones in the Royal Navy as a command platform for them. With fewer ships overall it might also mean that things like the Type 31s or the few mine countermeasure motherships could be forced to be inefficiently used where a patrol ship would do.

The other place is manned aviation. There's only the promise of unmanned systems yet to be developed to do things like replace the Wildcat while the Merlin is held on to as long as possible. This at least to me seems an issue as manned aircraft are still the most effective anti-drone platforms as well as offer the ability for long range command and control of drones.

But what do you all think?

Image credit: Nammo

Relatively few options have been available especially defensively for underwater attacks on surface ships. Even if you say saw/heard a torpedo coming, you had best hoped you could outrun it as you had limited options to hitting it. With underwater and especially semi-submersible drones this could be a bigger issue than ever before

But maybe super-cavitating ammunition is a solution?

The USN already has one in service in the 30x173mm Mk 258 Mod 1 as seen in the graphic above, primarily in to my knowledge use for minesweeping, there’s theoretical usage even discussed by Nammo themselves which could include close range torpedo and submarine defense.

One of the big issues with this type of method would be that you would of course need to hit an underwater contact, which usually one doesn’t have a perfect position for. The other is that even the best performing projectiles can’t go that far underwater which would mean a pretty short ranged defense.

The bigger the projectile the longer ranged so if one had say a 5” (127mm) version it would have a massively higher effective underwater range and a meaningful explosive charge though you’d be giving up as good in-air performance.

But what do y’all think?

Could this be useful in a defensive role for surface ships? Or is it only good for mine clearing realistically?

With the ever increasing automation in both general ship systems and more specifically use of drones in mine countermeasure operations it seems like a good solution for navies to keep up their numbers of corvettes/frigates/sloops. There’s no longer as much a need for a ship to be non-magnetic and crew numbers between these types are narrowing.

There’s pictures are of three examples, of various time and effectiveness from the very well received Mogamis that are very much a frigate first, to the LCSs that tried to do too much, to the WW2 equivalent of Japanese minesweepers that were very heavily armed for their size and meant to help with things like bombardment even.

It’s kind of a follow up to my last post. If expecting a ship class to do so many roles then was too much, maybe just these two could still work?

What do y’all think generally? Is it better to have separate classes, or for especially certain types of navies does this make the most sense?

I think that the Royal Navy is the most interesting to talk about in terms of modern hypotheticals. They are decently sized, fairly well funded, and have their illustrious history but with issues and commitments to match all of these things. As it now stands, their problems from what I’ve read are mostly their lack of suitable escorts, few amphibious warfare vessels, a decreasing mine countermeasure capacity while having even more manning shortfalls than everyone else.

So the question I think is begged: Could these all be at least to a degree resolved in a single ship class?

The Type 32 frigate idea already seems like the RN themselves’ idea in this regard though if that could ever now come to be is another story. It’s interesting though to see ships that other nations have or are building that could add so much.

Firstly that comes to my mind, something like an improved LCS. As many problems as they have, at least the Independence class are giving good service and are lightly manned potentially very useful ships. Make them more dedicated mine countermeasure vessels and drone carriers, with SeaCeptors as part of the armament, and it seems like such light frigates could be a welcome addition. And if need be, the royal marines should be able to be fitted with some vehicles inside the roomy mission space.

The Absalons are maybe the most obvious choice of what an actual Type 32 could be based one. More heavily manned but a much larger ship that was built on a budget, in their original guise as multi-mission ships they could do almost anything with their vast mission space including explicitly amphibious warfare while still being a venerable warship. With a more drone focused approach, things could be even better today and it’s what the Type 31s are based on.

The last is the Portuguese drone carrier D. Joao II. Now the RN would probably need to do things like significantly up the speed of any design to keep up with other ships and have it be better armed, but with drones now adding so much to what a ship can do, these ultra-light carriers seem like they could be a way to cover many bases at once. The San Giorgio class LHD might be an even better, specifically something like the Qatari Al Fulk which has a frigate level armament.

All of these seem like in theory they should also help with things like hydrographics if needed (another somewhat atrophying area), and the modular mission loads that are being experimented with seem like they are also suited to this type of ship.

But what do y’all think?

What would be the best type of ship for the Royal Navy to procure?

Maybe you think that these all should come secondary to more replenishment vessels?

Or maybe something more like a much smaller patrol minesweeper so high end ships can be left to do their things?

Or should the Type 83 program be made sure not to get delayed first and foremost?

Weight of shell is one of the most important factors in a naval gun of the earlier 20th century, especially needing to consider what a can be handled by sailors due to less machinery assistance than would be found later in the century. It would seem to me though that 150 lbs, equating to about a 170mm or 6.7" gun, would be one of the optimal calibers. One strong man's maximum to handle repeatedly with some ease is about 75lbs, and this can be seen in naval shells and cartridges like the 5.5" which had an 80lbs shell for that reason or the 5"/25 who had an 80lbs cartridge. These guns were able to have a good rate of fire seemingly proving the idea. Thus it would seem to stand to reason that to have the maximum effectiveness of a gun which with a shell two men could handle the shell of that it would be 150lbs or maybe slightly more.

It would also be the largest reasonable for a separate cartridge system before automatic weapons as the powder and casing should weigh in the neighborhood of 80lbs so could be handled by a single man.

In addition to it being of a good weight to achieve a good rate of fire, being about 1.5x the weight of a standard 6" shell would give the ships a ballistic advantage over light cruisers so armed. As cruiser armor often only really gave protection from 6" shell, it would seem this would likely be the minimum to be fairly confident at being able to overwhelm one's foes.

Pictured is a 17cm SK L/40, one of the few naval weapons which had about this shell weight (lighter trending German shells meant it was 141lbs), spending its second life as part of the Atlantic Wall.

Was the lack of use if weapons in this caliber simply inertia with the long history of the 6"/155m and then the naval treaty limit of 8"? Or was something like this really slightly too big and the 130lbs heavy 6" shell really the reasonable max for a high rate of fire naval gun?