Your Nation's Warships, Batch 3

[United Earthlings]

I’m well aware of the limitations of SpringSharp, so to reiterate I was merely showing what was possible, not what was realistic in answer to Taihei Tengoku’s question of “what is the minimum practical displacement”.

To further clarify, I think it’s possible for Taihei Tengoku to be able to have a ship design with a practical displacement of somewhere between 3,400 and 3,600 standard tons vessel that meets their range requirements. What realistically said ship design could accommodate in weight for sensors and armament I’m unsure of. This is why I’m also of the opinion that Taihei Tengoku should just forget the minimum practical design and instead simply focus on a more multipurpose larger derivative design exclusively instead of as the latter part of their design plan phases.

Alternatively, if you want to get a bit crazy and go for super ultra maximum range: sailboats.

If were voting on crazy sailing vessels, then my vote goes to a modern version of large clippers and windjammers like this & this.

I also believe it places far too much weight on speed when it comes to calculating seakeeping (I don't buy that my knock-off HMS Devastation is a good seaboat, no matter how slowly it goes).

I don’t understand the problem. By all historical accounts, HMS Devastation (the 1871 one) was a pretty good sea boat. You’re recreating a design as accurately as possible that was a good seaboat historically, but are somehow mad that’s its imperfectly generated computer model is also still a good seaboat. That makes no sense.

“Devastation proved successful on trials, being a steady gun platform and a good steamer. Although her forecastle was subject to being washed down in a seaway, she was a good seaboat and rolled and pitched less than many broadside ironclads. She generally remained dry amidships and heavy weather did not affect her fighting ability except for her low freeboard fwd limiting her speed.”

[New Vihenia]

I'm also pretty sure that it overestimates horsepower requirements to attain a given speed, though that could be a result of the limited control we have over the actual hullform of the ships. I also believe it places far too much weight on speed when it comes to calculating seakeeping (I don't buy that my knock-off HMS Devastation is a good seaboat, no matter how slowly it goes).

Power requirement is historically difficult to estimate... Even Holtrop Mennen is based on statistics. I wont be too hard on Springsharp or any other attempt to do so.

---------
The most rudimentary thing is perhaps to use the range equation for surface cruising of Diesel Electric Submarine.



Worked example :


This equation also takes account of the ship's own electric power consumption. Though it can be set to 0 as surface ship may have its own service generator separate from the propulsion but may still share fuel.

[Gallia-]

NSC carries around the lower end of Danton's estimation of 800-1000 tons of diesel fuel (225,000 gallons full up). An extra 40,000 gallons and only diesels (CODAD?) for propulsion would probably be sufficient to meet the range of 15,000 nmi in the same hull.

You'd need to go pretty slow and be in fairly calm weather, though. NSC gets her 12,000 nmi range at 6 knots.

[Taihei Tengoku]

Perhaps. The plausible enemy doesn't have infinite MPAs or submarines but I don't have infinite technology either (~late 00s China). It would be nice to print Burkes/Luyangs but I cannot, and in any case there would be AAW destroyer leaders in the escort package

Fair enough. This is probably a good time to ask what exactly your potential adversaries have that could theoretically attack these ships at sea when they're performing their design role. We talking SSNs and carriers, long-range land-based naval aviation, or a bunch of SSKs and frigates?

40mn/$40k GDPPC island country to my immediate west with six SSN, another 40/$40k island farther to the north-east with seven SSN and two non-nuclear carriers, and the British Raj on my immediate north with only SSK and LHA. I have no carriers but thirteen SSN and fifty SSK of various quality.

NSC carries around the lower end of Danton's estimation of 800-1000 tons of diesel fuel (225,000 gallons full up). An extra 40,000 gallons and only diesels (CODAD?) for propulsion would probably be sufficient to meet the range of 15,000 nmi in the same hull.

You'd need to go pretty slow and be in fairly calm weather, though. NSC gets her 12,000 nmi range at 6 knots.

A high inverted bow seems to do very well maintaining speed and stability in bad seas if Ulstein's marketing is to be believed. I need 15,000nmi at 18~20 knots though, this might push the displacement up to 5~6000t.

[United Earthlings]

How dead set are you on this vessel design having to be a surface escort? The initial financial investment would be larger, but a small nuclear attack submarine with a length somewhere between 280 and 300 feet would fulfill the operational requirements you have laid out quite well. In additional, seeing as your nation already produces nuclear attack submarines, you already have the existing infrastructure in place should you choose to build a new SSN class. This would also greatly reduced costs in the new design as technology developed for your previous SSN class could be carried over. Furthermore, when not escorting convoys, you have a very capable vessel that can be assigned other missions and roles instead of just sitting in port awaiting the next scheduled convoy.

Finally, a small nuclear attack submarine would also have inherit tactical advantages a mid-sized long range surface escort wouldn’t.

[The Corparation]

How dead set are you on this vessel design having to be a surface escort? The initial financial investment would be larger, but a small nuclear attack submarine with a length somewhere between 280 and 300 feet would fulfill the operational requirements you have laid out quite well. In additional, seeing as your nation already produces nuclear attack submarines, you already have the existing infrastructure in place should you choose to build a new SSN class. This would also greatly reduced costs in the new design as technology developed for your previous SSN class could be carried over. Furthermore, when not escorting convoys, you have a very capable vessel that can be assigned other missions and roles instead of just sitting in port awaiting the next scheduled convoy.

Finally, a small nuclear attack submarine would also have inherit tactical advantages a mid-sized long range surface escort wouldn’t.

An SSN would be awful at fulfilling the operational requirements of a surface escort while also costing more.

[Nevertopia]

our standard fighter jet the Eagle mk2.
Capable of orbital warfare.
equipped with dual burst lasers and a missile launcher.

Eagle mk2

[The Manticoran Empire]

our standard fighter jet the Eagle mk2.
Capable of orbital warfare.
equipped with dual burst lasers and a missile launcher.

Eagle mk2

Very pretty. My question is why the lasers? Lasers require a lot of power in order to be really effective or they have to maintain contact with the target for a relatively long time. So why lasers instead of additional missiles or KEWs?

[Ormata]

our standard fighter jet the Eagle mk2.
Capable of orbital warfare.
equipped with dual burst lasers and a missile launcher.

Eagle mk2

Very pretty. My question is why the lasers? Lasers require a lot of power in order to be really effective or they have to maintain contact with the target for a relatively long time. So why lasers instead of additional missiles or KEWs?

Better question is why is this, a space plane, being posted in a warship thread?

[The Manticoran Empire]

Very pretty. My question is why the lasers? Lasers require a lot of power in order to be really effective or they have to maintain contact with the target for a relatively long time. So why lasers instead of additional missiles or KEWs?

Better question is why is this, a space plane, being posted in a warship thread?

That's a good point.

[United Earthlings]

An SSN would be awful at fulfilling the operational requirements of a surface escort while also costing more.

That's not what I was saying...if the main overall operational requirement is to safeguard the convoy supply lines, there’s more than one way to accomplish that objective. Ideally, funds permitting, TT would be pursuing a shipbuilding developmental plan that offered multiple paths that successfully denied access to their nation’s interior SLOCs.

As for cost, without a direct comparison between two specific types of vessels, an SSN may or may not cost more than a surface escort depending on the specific type of surface escort that’s being compared. There’s also the specific cost being compared, Total Program Costs? Just R&D costs or Unit Production Costs {either individual or an average)?

[Taihei Tengoku]

The SSNs are already being used to secure the SLOCs. My country is building them as fast as they can in all the shipyards that can build them. However, it still needs a close protection escort for its convoys, which will have to be a surface vessel.

[Barfleur]

The SSNs are already being used to secure the SLOCs. My country is building them as fast as they can in all the shipyards that can build them. However, it still needs a close protection escort for its convoys, which will have to be a surface vessel.

If the UK exists in your world, see if you can buy into the Type 26 program. With UK, Canada, and Australia in, it shouldn't be too hard to involve your nation.

[Taihei Tengoku]

The UK does not exist in this world.

[Gallia-]

I wonder how fast Shikishima sails.

She has big range for nuclear waste transportation to Europe but I dunno at what speed.

[The Corparation]

An SSN would be awful at fulfilling the operational requirements of a surface escort while also costing more.

That's not what I was saying...if the main overall operational requirement is to safeguard the convoy supply lines, there’s more than one way to accomplish that objective. Ideally, funds permitting, TT would be pursuing a shipbuilding developmental plan that offered multiple paths that successfully denied access to their nation’s interior SLOCs.

As for cost, without a direct comparison between two specific types of vessels, an SSN may or may not cost more than a surface escort depending on the specific type of surface escort that’s being compared. There’s also the specific cost being compared, Total Program Costs? Just R&D costs or Unit Production Costs {either individual or an average)?

1) Securing sealanes with SSNs alone is not a replacement for convoy escorts.
2) Ship per ship a SSN is almost always going to cost more than a simple convoy escort. Nuclear ships cost more to build and maintain than a conventional ship and surface ships are generally cheaper than submarines.

It's as if TT is asking for advice on buying a pickup and you're desperately trying to sell him a Ferrari. Except even sillier because for the sake of this hypothetical he's already stated he owns a Ferrari.

[United Earthlings]

1) Securing sealanes with SSNs alone is not a replacement for convoy escorts.

I didn't say the SSNs should be built alone, had you read the second link I provided you would have better understood what I was trying to convey, so here is the relevant part again.

"Put simply the Navy's basic approach to the Soviet threat is to interpose a series of barriers between Soviet submarine bases and their targets. For example a Soviet submarine moving from its home base to the principal shipping lanes in the Atlantic and the Pacific would have to pass through mine fields and through zones patrolled by U.S. attack submarines it would then be subjected to intensive air patrols by land based patrol aircraft and by patrol aircraft from ASW carriers. Finally to attack a convoy it would have to penetrate a destroyer escort screen if the submarine were successful in its mission it would then have to pass through all these barriers again on its way home. The barrier concept can be illustrated with a simplified hypothetical example. Assume first of all that the Soviets have 200 submarines that can be used to attack our shipping in the Atlantic and the Pacific. Assume also that the United States deploys a total of five barriers in each ocean: mines, submarines, land based patrol aircraft, carrier based patrol aircraft and destroyers in that order which their submarines must traverse to reach our convoys."

Depending on the mostly likely threats against TT's convoys whether surface, subsurface or both. Expand this barrier concept from only submarine counter to factor all potential threats to the convoys. If only enemy submarines, nuclear or otherwise are a threat to the convoys, then ideally increasing one's own submarine numbers {nuclear or conventional} would probably be the most cost effective in addition to pursuing one, more or all of the other options.

TL;DR: A surface escort may or may not be necessary that directly escorts the convoy. If one can intercept the majority of threats against the convoys before said threat reaches the convoys, then direct LOS protection of the convoys becomes less relevant and the surface vessels that have been built can be tasked to other missions.

2) Ship per ship a SSN is almost always going to cost more than a simple convoy escort. Nuclear ships cost more to build and maintain than a conventional ship and surface ships are generally cheaper than submarines.

All generally true except for the fact that simple convoy escorts aren't built anymore. Depending on what type of specific surface escort TT’s ultimately settles on which could be anything from a General Nuclear Powered Destroyer, an ASW focused Destroyer like the Russian Udaloy class or even an ASW Carrier like the Japanese Hyūga-class. The point being the larger and more capable the vessel design is, the more expensive it will be, this goes for both SSNs, SSKs and every type of surface warship.

It's as if TT is asking for advice on buying a pickup and you're desperately trying to sell him a Ferrari. Except even sillier because for the sake of this hypothetical he's already stated he owns a Ferrari.

A good salesman will try to show every option on the lot, especially if the customer has little idea what they want. So, over there is the nice Minivans, there is the SUVs and over there next to the pickups are my favorite, the Roadsters. Sadly, fancy Sports cars like a Ferrari are custom orders and not available for viewing on this lot at this time.

However, across the street my friend is selling Ferrari tractors if you’re interested.

“Admiral James wrote that: In view of these technical facts of life and the size of the total program envisaged, I cannot but wonder if the time has come when we should seriously question the wisdom of continuing to emphasize the surface ship as our primary ASW vehicle. . . we are trying to accomplish the job “the hard way,” expending a tremendous effort to get our sonars deep in the water where the acoustic problems will disappear. . . there is no question but that a surface ship is not a good sonar platform nor, indeed, is it likely that we will ever succeed in making it somewhat more than marginal. A submarine, on the other hand, represents a near optimum sonar platform. . . Few dare to express [this conclusion] openly, for it is not a generally palatable subject. . . .[The submarine] does have two disadvantages at the present, communications and cost. . . I would not propose that the submarine be assigned as the sole ASW vehicle. Some surface types would inevitable be required for use in shallow waters, for escorting convoys in areas where air attack is possible. . . and in other multi-purpose roles. I do espouse the submarine as the primary vehicle…” U.S. Destroyers Revised Edition, Pg 363.

What I’ve been proposing is not some radical concept.

[Triplebaconation]

Nobody cares.

[Mitheldalond]

How much more expensive is it to build a submarine out of titanium compared to steel? The sources I've found claim working with titanium is 3-5 times more expensive than steel, but that's just for the hull. For surface ships, the cost of the hull is only a small fraction of the total cost, with the electronics and weapon systems making up the majority of it. I'd assume the same is true for submarines, so how much of an effect would titanium really have on the total cost of a sub?

[The Akasha Colony]

How much more expensive is it to build a submarine out of titanium compared to steel? The sources I've found claim working with titanium is 3-5 times more expensive than steel, but that's just for the hull. For surface ships, the cost of the hull is only a small fraction of the total cost, with the electronics and weapon systems making up the majority of it. I'd assume the same is true for submarines, so how much of an effect would titanium really have on the total cost of a sub?

What are you starting from?

The industrial capacity to work the huge titanium sections needed to build a submarine is not something that nations generally have laying around because there is little other use for such capabilities. This is why the USSR had to invest so many resources developing these processes themselves. But once built, assuming you have a fairly ready supply of titanium, the sunk cost has already been paid so producing additional titanium submarines isn't terribly expensive. The USSR continued to produce steel submarines alongside their titanium boats because they still had a huge industrial base that was familiar with steel so meeting their desired force targets could only be done with steel boats. The USSR didn't really reckon in dollar (or ruble) costs for their titanium submarines vs. their steel submarines.

Which once again means that "cost" is going to depend on what you have available. The USSR had lots of titanium, making it a reasonably cheap option. The US did not have such ready access to titanium. Ready access to titanium also meant the USSR had a larger industry with which to process it and from which to develop the processes for submarine hull fabrication. And the Soviets had deeper diving requirements than US submarines, which would have required very thick, heavy pressure hulls had they not experimented with building them from titanium.

[United Earthlings]

How much more expensive is it to build a submarine out of titanium compared to steel? The sources I've found claim working with titanium is 3-5 times more expensive than steel, but that's just for the hull. For surface ships, the cost of the hull is only a small fraction of the total cost, with the electronics and weapon systems making up the majority of it. I'd assume the same is true for submarines, so how much of an effect would titanium really have on the total cost of a sub?

AC had it right in that a direct apples-to-apples cost comparison isn't possible. So, in that regard I would concede as a simple baseline that a 3-5 times more expensive approach is ok, if less than 100% accurate. Since again, as AC so elegantly and correctly stated, where are you along the production process? And of course whose economic system are you following. Depending on those two variables plus many more other variables then I have fingers to count on could influence the cost way higher than 5 times more expensive.

However, all that stated it may or may not surprise you that you’re not the first person to ask that question as with a little bit of google kung-fu I was able to find this little gem from a 1981 Senate Armed Services Defense Appropriations hearing {Note, you should read the full context before and after the following quote since again many of the issues AC pointed out are again pointed out during the hearing}: “ALFA Class SSN Estimated Cost: The estimated cost of construction of a Soviet ALFA Class SSN in US dollars were it to be built in a US shipyard for the lead unit could range from $738 million to $1,051 million ($79), with follow on units costing some $577 to $844 million each. This does not include the cost for a titanium R&D program, nor for a reactor prototype and site”

By way of non-comparison, the listed construction cost for the 32nd Los Angeles class SSN in fiscal year 1978 dollars was $343 million.

What are you starting from?

The industrial capacity to work the huge titanium sections needed to build a submarine is not something that nations generally have laying around because there is little other use for such capabilities. This is why the USSR had to invest so many resources developing these processes themselves. But once built, assuming you have a fairly ready supply of titanium, the sunk cost has already been paid so producing additional titanium submarines isn't terribly expensive. The USSR continued to produce steel submarines alongside their titanium boats because they still had a huge industrial base that was familiar with steel so meeting their desired force targets could only be done with steel boats. The USSR didn't really reckon in dollar (or ruble) costs for their titanium submarines vs. their steel submarines.

Which once again means that "cost" is going to depend on what you have available. The USSR had lots of titanium, making it a reasonably cheap option. The US did not have such ready access to titanium. Ready access to titanium also meant the USSR had a larger industry with which to process it and from which to develop the processes for submarine hull fabrication. And the Soviets had deeper diving requirements than US submarines, which would have required very thick, heavy pressure hulls had they not experimented with building them from titanium.

Apologies in advance for nitpicking such a small part of a well written post, but the part I bolded is incorrect. Supply was never an issue for the US, the ebb and flow of demand was.

[Mitheldalond]

Behold! My first proper(ish) full write-up. (Ironically, most of the information here would be highly classified.)

They probably look mostly like a smaller Seawolf.

Uinen-class hunter-killer attack submarine (SSN):

• Length: 320 ft / 97.5m, Beam: 36 ft / 10.97m
• Cost: $2-2.8 billion
• Number of Vessels: 30 building or in service (ongoing construction program)
• Designed/Introduced: early 2010s
• Power/Propulsion: nuclear reactor, lithium-ion batteries, pump-jet propulsor
• Speed: >30 kts submerged (actually 35 kts)
• Range: unlimited (nuclear)
• Test Depth: officially 800+ ft / 243.8m (actually ~1800 ft / 548.6m, with crush depth 2700+ ft / 823m)
• Crew: ~70
• Armament:
  • 6 x 26” torpedo tubes (26 weapon racks; typical loadout 20 x Mk 48 torpedoes, 6 x 21” MOSS decoys)
  • 2 x 7-cell VLS silos
    • 13 x UGM-111 Fëanar (stealthy long-range anti-ship and land attack cruise missile), or UGM-109 Tomahawk
    • 4 x IDAS SAM (1 cell)
    • 1 or both silos can be fitted with either a lock-out chamber for special forces, or a swimmer delivery vehicle (if those can be carried vertically and travel horizontally) in place of missiles

The Uinen (pronounced oo-ee-nen) is the newest class of vessel in service with the Mitheldalondian Navy. Unlike the previous multi-purpose Ossë-class guided missile attack submarines introduced in the 1990s, the Uinen is a dedicated hunter-killer, intended to hunt down and destroy high performance enemy submarines.

The design program was initiated in response to the increasingly widespread proliferation of advanced diesel-electric boats with air-independent propulsion, and the introduction by several other nations of advanced nuclear submarine programs. (Or because I watched too much Cold Waters gameplay on YouTube and slightly freaked out at how easily modern subs run around massacring everything in sight without even being detected.) The impressive stealth capabilities of small, affordable AIP diesel boats were of particular concern to the Navy, which worried that Mitheldalond's then-existing ASW measures would be inadequate to protect carrier groups from such threats. Thus, the Navy initiated a new program aimed at drastically improving Mitheldalond's ASW capabilities. Among other changes, this program called for a new, cheaper frigate with enhanced anti-submarine performance (the new Elwing-class frigate), and a new attack submarine which would be capable of detecting and sinking even the quietest modern subs before they could get close enough to threaten a carrier group, without being detected itself. This would become the Uinen-class.

In regards to the Uinens' stealth characteristics, the Navy - which generally deliberately understates the abilities of their ships, at least with regards to their true specifications - has described them as "quieter than a Seawolf", "second to none", and more conservatively as "easily one of the quietest submarines ever built" in various press releases. The boats are built of high strength non-magnetic steel, which makes them difficult to detect with magnetic anomaly detectors and unlikely to set off magnetic mines. The outer hull is as smooth and as free of protrusions (which would disturb the flow of water) as possible. The sail is blended smoothly into the hull, eliminating any sharp transitions and further smoothing the flow of water. Thick anechoic tiling covers the exterior hull, while the interior is fitted with extensive soundproofing. All machinery and moving components are mounted on vibration-absorbing rubber pads, and the decks are lined with no-slip rubber matting designed to muffle the sound of footsteps.

They are fitted with an advanced pump-jet propulsor featuring a composite multi-material rotor, which is said to virtually eliminate cavitation. This allows the Uinen to achieve higher speeds more quietly than other submarines at any given depth. X-form stern planes allow them to operate in shallower water than would be possible with a conventional vertical rudder arrangement, and enable them to rest on the seabed without damaging the rudder. They can also be made smaller than the usual cruciform planes without sacrificing maneuverability. This makes them quieter, as smaller planes both produce less drag and require smaller motors to actuate them. Thus, the use of X-form stern planes increases both the Uinens' maneuverability and stealth.

The need to constantly circulate reactor coolant is a major source of noise on even the quietest nuclear submarines, and is one of the main reasons it's considered possible to make an AIP-equipped diesel-electric boat quieter than a nuclear one. The Uinen is one of only a handful of nuclear submarines that have the ability to operate with their reactor pumps secured (turned off). When this is done, the only moving parts left to produce sound are the propeller shaft and motor, making them quieter than many AIP boats, which often have additional moving parts (Stirling engines for example). However, this can only be done for a short time before the reactor is in danger of overheating. The Uinen-class solves this problem by reducing reactor output to the minimum level necessary to sustain the reaction (they could just shut down the reactor completely, but this runs the risk - however slight - of not being able to restart the reactor, so it's rarely done). This dramatically reduces the amount of heat produced, which allows the Uinens to operate significantly longer with pumps secured, or to circulate coolant much more slowly and quietly. When operating in this mode, the boats run entirely on battery power. They use lithium-ion batteries - which have a much higher capacity than the older lead-acid types - and carry an unusually large number of cells for a nuclear boat, allowing for up to three days of operations at a speed of around 5 knots. Unlike diesel-electric subs, an Uinen does not have to surface to recharge her batteries; she simply has to increase her reactor output to normal levels.

The Uinen-class makes extensive use of advanced active noise and vibration cancellation technology. Arrays of microphones and speakers are strategically placed around the hull, and at key areas that produce the most noise. Such locations include in the pump-jet shroud, where the propeller shaft exits the hull, and around other moving components. As with other active noise cancellation technologies, these systems are best suited to cancelling out continuous, periodic sounds like the hum of electric motors and pumps, the circulation of coolant for the reactor, the sound of the propulsor as it moves through the water, the spinning propeller shaft and bearings, and the interaction of the hull with the water around it. However, the Uinen can also cancel out more sudden sounds with known acoustic signatures, like the opening and closing of torpedo tubes and missile hatches, the flooding or emptying of ballast tanks and torpedo tubes, and the motion of the bow and stern planes. Her systems may also attempt to cancel out unexpected random sounds such as objects falling or being dropped within the sub, or even active sonar pings from other vessels, but this is significantly more difficult, as such sounds would have to be detected, analyzed, and replicated (in reciprocal) almost instantly for noise cancellation to be truly effective. Other systems are present which detect vibrations originating from within the submarine and act to counteract them at the outer hull, preventing them from being transmitted into the surrounding water as sound. Precise timing is required for all of these operations to be effective.

Additionally, the Uinen-class has multiple electromagnets positioned around the hull that actively counteract their already small magnetic signature, rendering them almost immune to magnetic anomaly detectors and magnetic mines. Excess heat is channeled out the bottom of the hull, and the boats are equipped with active temperature control systems. This cuts down on any IR signature that might be detectable by aircraft or surface platforms.

In addition to their extreme stealth, the Uinen-class carries a wide array of highly capable, highly sensitive sonar arrays, including a large diameter spherical bow sonar, side-mounted wide-aperture arrays, an aft-looking array mounted in the sail, and variable depth high and low frequency towed arrays. These systems were all designed to detect high performance nuclear and AIP diesel-electric submarines. Even so, Uinen-class boats have reported difficulty detecting and tracking each other in exercises.

[The Akasha Colony]

The need to constantly circulate reactor coolant is a major source of noise on even the quietest nuclear submarines, and is one of the main reasons it's considered possible to make an AIP-equipped diesel-electric boat quieter than a nuclear one. The Uinen is one of only a handful of nuclear submarines that have the ability to operate with their reactor pumps secured (turned off). When this is done, the only moving parts left to produce sound are the propeller shaft and motor, making them quieter than many AIP boats, which often have additional moving parts (Stirling engines for example). However, this can only be done for a short time before the reactor is in danger of overheating. The Uinen-class solves this problem by reducing reactor output to the minimum level necessary to sustain the reaction (they could just shut down the reactor completely, but this runs the risk - however slight - of not being able to restart the reactor, so it's rarely done). This dramatically reduces the amount of heat produced, which allows the Uinens to operate significantly longer with pumps secured, or to circulate coolant much more slowly and quietly. When operating in this mode, the boats run entirely on battery power. They use lithium-ion batteries - which have a much higher capacity than the older lead-acid types - and carry an unusually large number of cells for a nuclear boat, allowing for up to three days of operations at a speed of around 5 knots. Unlike diesel-electric subs, an Uinen does not have to surface to recharge her batteries; she simply has to increase her reactor output to normal levels.

I'm not sure if this is some kind of intentional IC technology shortcoming, but natural circulation reactors have been capable of operating indefinitely without pumps for over 50 years, without any danger of "overheating" or some kind of time limit. IIRC the newer NCR designs in boats like Virginia can provide something like 30-40% of maximum output without the pumps, so they can provide quite a lot of power while silent without any concern about overheating.

The relative noise output of a diesel boat and a modern SSN is more or less irrelevant; both are quieter than the ambient ocean and therefore essentially equally undetectable by passive means at any useful distance.

Even so, Uinen-class boats have reported difficulty detecting and tracking each other in exercises.

This is generally true of most modern submarines: even modern passive sonar is generally no longer very effective at detecting modern submarines, be they nuclear or diesel.

Weapons complement seems light and unusually arranged for a hunter-killer. The Los Angeles-class was considered to be uncomfortably short of stowage with only 25 torpedoes, which is why the 12-tube VLS was added. But the VLS obviously didn't increase torpedo storage, it improved land-attack capability. A hunter-killer would be armed more like Seawolf or Astute: more torpedo room space, less or no VLS. Since Tomahawks and Harpoons can be fired from the torpedo tubes anyway, this is enough to provide basic surface attack capability if needed.

It's nice to see something that isn't a titanium-hulled gigasub though.

[Velkanika]

It's nice to see something that isn't a titanium-hulled gigasub though.

There's a reason I retconned my gigasub to be a total white elephant of an acquisition program XD

On the subject of modern subs and passive sonar, "quieter than x class" means literally nothing. Modern quieting improvements have really been about isolating and eliminating specific frequency bands rather than reducing the overall volume of noise radiated. Likewise, modern passive sonar advances are primarily on the processing end to look for patterns of noise in specific frequency bands.

[Izukyu]

Asking this question as someone with zero naval knowledge, so apologies in advance.

Say I have an modestly-sized island nation with no standing navy, but a rather robust Coast Guard that acts as a coastal defense force / maritime law enforcement agency.

What kind / type of vessels should I be focusing on?