Replacing the Subs

[Colin Parkinson]

There are not "requirements" yet. There will be range, weapons and indiscretion rate requirements, as well as crew complement requirements. But likely there never be a tonnage one. Tonnage is not a capability. Might be size constraints/restraints though.

Tonnage equals room for crew, fuel, food, water, weapons and sensors. I don't get to see the real spec of each sub, but there is only so much you can cram into a boat and then be able to live in it for an extended period of time. Without tonnage, you are likely compromising something.

 

[Oldgateboatdriver]

I think what Underway is saying is that we do not start by saying "we want a boat of XYZ tonnage". You start by stating what the boat has to be capable of performing in term of range, time of operation underwater, food storage, weaponry, combat systems, etc. Once you have those, the various bidders develop their plans and come up with a hull that can fit all this in, and that gets you your tonnage.

Depending what you want to put in, a 2000t boat can be just as crammed, or can have more living space than a 3000t one. It's your choice as to what you put in the box.

 

[KevinB]

Tonnage equals room for crew, fuel, food, water, weapons and sensors. I don't get to see the real spec of each sub, but there is only so much you can cram into a boat and then be able to live in it for an extended period of time. Without tonnage, you are likely compromising something.

Tonnage and power also give the potential for ice breaching for surfacing, but as @Oldgateboatdriver points out tonnage isn't a specific characteristic - as if you say needs to do X,Y,Z that will lead you to a basic minimum and industry will attempt to meet those KPP's.

 

[Colin Parkinson]

I think what Underway is saying is that we do not start by saying "we want a boat of XYZ tonnage". You start by stating what the boat has to be capable of performing in term of range, time of operation underwater, food storage, weaponry, combat systems, etc. Once you have those, the various bidders develop their plans and come up with a hull that can fit all this in, and that gets you your tonnage.

Depending what you want to put in, a 2000t boat can be just as crammed, or can have more living space than a 3000t one. It's your choice as to what you put in the box.

The Germans as I recall have been offering an extended version of what they produce already, so even they seem to recognize that their subs are to small for the Pacific. For people outside the loop, tonnage is one potential indicator of capability. Also likley means more crew comfort as well.

KSS-III batch 2 - 3,600 t (3,500 long tons) (Surfaced)
Scorpene - 1,900 t (1,900 long tons) (S-BR)
Taigei - Surface: 3000 tonnes
Orka- 3,300 t (3,248 long tons) surfaced (Contracted, but not built yet)
Type 212CD- 2,500 t (2,500 long tons) surfaced
Type 214- 1,690 t (1,660 long tons) (surfaced)
S-80-Plus- 2,965 t (2,918 long tons) submerged
Blekinge - 1,925 tonnes (1,895 long tons; 2,122 short tons) surfaced
Soryu- Surfaced: 2,900 tonnes , Submerged: 4,200 t (I have to wonder how accurate the submerged figure is as it is the greatest differential of all the sub types?

 

[Kirkhill]

Some interesting developments in long rang comms with submarines apparently

Australia controls UK submarine from 10,000 miles away

The Royal Navy has demonstrated for the first time that its new submarine Excalibur can be controlled from the other side of the world, with operators in Australia directing the uncrewed submarine while it was submerged in UK waters.

ukdefencejournal.org.uk

The Royal Navy has demonstrated for the first time that its new Experimental Vessel (XV)​

The test, carried out in July during Exercise Talisman Sabre 2025’s “Maritime Big Play” series, was part of the AUKUS Pillar II programme to develop and share advanced technologies, according to a Royal Navy news release.

The 12-metre Excalibur is the Royal Navy’s first Extra Large Uncrewed Underwater Vehicle (XLUUV), unveiled earlier this year after a three-year development project known as Cetus.

Royal Navy’s first XLUUV is formally named XV Excalibur - European Security & Defence

The Royal Navy unveiled and named its first extra-large uncrewed underwater vehicle on 15 May 2025 at a ceremony at HMNB Devonport.

euro-sd.com

Royal Navy’s first XLUUV formally named XV Excalibur - Navy Lookout

The RN’s development of uncrewed underwater systems took a significant step forward with the formal unveiling of its first Extra-Large Uncrewed Underwater Vehicle (XLUUV) today. Named XV Excalibur, the 12-metre long, 2.2-metre diameter vessel displaces 19 tonnes and is the largest uncrewed...

www.navylookout.com

 

[suffolkowner]

I don’t think Sweden has actually started its newest model of sub yet have they? Let alone even have one completed and at sea.

I think they are building the A26 right now with attendant issues with a first in class, cold yard

 

[Genetk44]

I think they are building the A26 right now with attendant issues with a first in class, cold yard

You are correct….delivery of the first sub is scheduled for some time in 2027 and a second one in 2028…..

 

[Oldgateboatdriver]

The Germans as I recall have been offering an extended version of what they produce already, so even they seem to recognize that their subs are to small for the Pacific. For people outside the loop, tonnage is one potential indicator of capability. Also likley means more crew comfort as well.

KSS-III batch 2 - 3,600 t (3,500 long tons) (Surfaced)
Scorpene - 1,900 t (1,900 long tons) (S-BR)
Taigei - Surface: 3000 tonnes
Orka- 3,300 t (3,248 long tons) surfaced (Contracted, but not built yet)
Type 212CD- 2,500 t (2,500 long tons) surfaced
Type 214- 1,690 t (1,660 long tons) (surfaced)
S-80-Plus- 2,965 t (2,918 long tons) submerged
Blekinge - 1,925 tonnes (1,895 long tons; 2,122 short tons) surfaced
Soryu- Surfaced: 2,900 tonnes , Submerged: 4,200 t (I have to wonder how accurate the submerged figure is as it is the greatest differential of all the sub types?

Difficult to judge, Colin, since the Soryu is the only one for which you give both surfaced and submerged figures.

However, here is the interesting thing about submarines: contrary to popular belief, they do not flood themselves to sink under water (nothing then would stop them from going strait to the bottom, like any other ship), they flood themselves to a point of neutral buoyancy - that is they neither sink, nor float -and are, after that, driven up or down to the level you want using the diving planes (one of the reasons the British practice of having the diving planes at the stem and at the stern is more efficient than the US practice of having them at the stern and on the side of the kiosk).

There are some small ballast tanks to help achieve a slight negative buoyancy for a short time to help with the original diving from the surface (in British submarines, they are referred to as Q-Tanks, Q stands for quick- so when first diving, you'll order the flooding of the main ballast tanks [numbered in British subs] like this: "Flood 1, 2, 5 and 6 ballast tanks. Flood Q"), but they are blown right back after achieving the original dive, so as to get back to neutral buoyancy.

The reason I say all that is because you can then make the following calculation for a submarine's submerged displacement: it equals exactly the weight of water corresponding to the full and exact volume of the submarine (another way of saying the density of a submerged submarine is equal to the density of water).

 

[daftandbarmy]

Nimby-ism: a powerful anti-sub weapon...

‘Good neighbour’ noise policy contributed to Esquimalt submarine accident​

Noise restrictions at Esquimalt dry dock identified as a contributing factor that compressed a work timeline and led to serious damage to HMCS Corner Brook while undergoing repairs

‘Good neighbour’ noise policy contributed to Esquimalt submarine accident

Noise restrictions at Esquimalt dry dock identified as a contributing factor that compressed a work timeline and led to serious damage to HMCS Corner Brook while undergoing repairs

www.timescolonist.com

 

[Sub Standard]

Canada’s naval commander wants submarine provider chosen by end of year

Looks like if CRCN gets his way we could have a decision by the end of the year.

 

[Czech_pivo]

Correct. However, there has been speculation that it might be coming soon.

Your comment looks to be spot on with today’s reports that the head of the RCN wants a sub picked by the end of this year.

 

[Czech_pivo]

Canada’s naval commander wants submarine provider chosen by end of year

Looks like if CRCN gets his way we could have a decision by the end of the year.

Friday afternoon in mid August this article comes out, lol.