Plan Type 095/096 Nuclear Submarine Thread


Higgle

Junior Member
Registered Member
I really don't understand why the barge is position between rail and dry dock. And why they need the dry dock in first place Don't they completed the submarine inside the construction hall.

Why not transfer from rail to the barge and slowly lowered the barge No need for dry dock like this video? Confused
Because the dry dock can be used for maintenance and repairs if there are no new boats being launched from the yard.

It also saves space since you don't need to build rails extending all the way to the sea, and then having to find space for a drydock somewhere else.

The dry dock might also be used to do some additional work or finishing touches on the boat immediately after launch, without transporting the hull to another part of the shipyard.
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Registered Member
I really don't understand why the barge is position between rail and dry dock. And why they need the dry dock in first place Don't they completed the submarine inside the construction hall.

Why not transfer from rail to the barge and slowly lowered the barge No need for dry dock like this video? Confused
For the purposes of launching a submarine, the drydock is unnecessary if you have a mobile barge or mobile drydock.

But for the purposes of fitting out, maintaining or refitting a submarine, having a drydock is useful.


For Bohai, they just happen to have a drydock and the barge connected, and it's a workflow that works and for the launch process I wouldn't say it is any better or worse than what the launch process that HII has for launching their submarines.


======


Also, in response to the HI Sutton article, cross posting what I wrote over on CDF, imo the article is not terrible but it makes a few potential mistakes:

The idea of 09V having a large diameter only makes sense if it's double hulled -- but we know there have been rumours for ages suggesting 09V is meant to be single or hybrid hulled instead. Also, if 09V has a beam as large as Akula, it will be too big for the SSN rail gauge which is only 7.34m, and each of the SSN slots are only 22.5m wide -- which won't provide enough clearance for a 13+ meter wide submarine like Akula.


... Also I find it a bit funny that Chris Carlson is finally seemingly admitting that the new facility is for nuclear submarines, despite being so strongly against the idea in 2017. Even in early 2019, when I had a conversation with James Fannell, apparently Chris Carlson was still of the opinion that the new Bohai buildings weren't for nukes.
Please, Log in or Register to view URLs content!

Please, Log in or Register to view URLs content!



.... what is very useful in article is the satellite picture showing the completed barge in position. We've known for a while that the barge would soon be complete, so it's nice that we have a picture of it.
 

Hendrik_2000

Brigadier
  • Thread Starter Thread Starter
  • #513
I though the reason for larger diameter has much to do with installation of raft inside the submarine and nothing to do with single or double hull
I can understand that any naval structure is cramp by nature with so many equipment and crew facilities competing for space . The other reason is vertical cruise missile tube that require bigger diameter

But I thought China has implemented the raft construction with their latest submarine type 93 III.

Yes Chris Carlson change his tune now I always thought it is obvious from the beginning that the Huludao facility is for building the new submarine Your article convincingly prove that But there is always tendency of western analyst to deny any Chinese progress in building better arsenal. It is wishful thinking really and denial mentality.
Here is his conclusion as to why the facility cannot be submarine construction hall which is faulty since they were observation from satellite and can't be verified of its accuracy How can you determine slab thickness for sofar?
Pile configuration is questionable too because we don't know what material that China used for pile ? And did he know what type of soil in Huludao ? clay, sandy, loam?
  • The foundation of the new building is insufficient to support the weight of a completed nuclear submarine The foundation’s pile configuration is designed primarily to stabilize the newly placed dredged sand to improve its load bearing capability and to mitigate uneven settlement.
  • The foundation slab is also rather thin for supporting the weight of a large, heavy vessel. A thickness of a meter, or more, is usually needed to bear such a huge load.
  • The design of this foundation can support objects that weigh several hundred tons, but not several thousand tons
 
Last edited:

ZeEa5KPul

Junior Member
Registered Member
The idea of 09V having a large diameter only makes sense if it's double hulled -- but we know there have been rumours for ages suggesting 09V is meant to be single or hybrid hulled instead.
Between single/hybrid and double hulls, which is more technologically advanced?
Also, if 09V has a beam as large as Akula, it will be too big for the SSN rail gauge which is only 7.34m
Why's the SSN rail gauge at BSHIC so narrow? I believe that it's >8m at other comparable yards.
Even in early 2019, when I had a conversation with James Fannell
Where was this?
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Registered Member
Between single/hybrid and double hulls, which is more technologically advanced?
It's not so simple and I don't want to answer it in a way that makes it sound like "PLAN should go for X rather than Y cause X is more advanced".

However, previous PLAN SSNs have been double hull, and it's been rumoured for quite a while now that 09V will likely be single or hybrid hull rather than double.


Why's the SSN rail gauge at BSHIC so narrow? I believe that it's >8m at other comparable yards.
7.34m is fine for an SSN. For example at Newport their gauge is just over 8m.

newport news launch.jpg

More importantly, the actual rail gauge itself doesn't mean the cradle of the submarine is fixed to the rail gauge.
See this picture of a Virginia being launched at Newport -- the cradle platform itself (the green square structure below the submarine) is overall at least 2-3m wider than their rail gauge itself. The rail gauge only supports the wheels (the blue twin wheels below the green square structure) which helps move the cradle -- but the cradle and the submarine atop it can be significantly wider than the rail gauge itself.

USS-Indiana-SSN-789-Launch.jpg


Where was this?
Over the internet a private conversation.
 

ZeEa5KPul

Junior Member
Registered Member
Thanks for the response @Bltizo. What do you think of Sutton's assertion that 09-V is not likely to use a pump-jet propulsor? @by78 posted some scientific studies of various pump jets; given that the work was published in 2016 (and I presume held under a publishing embargo for some time), I feel that China has had enough time and experience with this design to field it on the Type 09-V/VI - do you agree?

Also, do you think the Type 09-V/VI will have full electric propulsion?
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Registered Member
I though the reason for larger diameter has much to do with installation of raft inside the submarine and nothing to do with single or double hull
I can understand that any naval structure is cramp by nature with so many equipment and crew facilities competing for space . The other reason is vertical cruise missile tube that require bigger diameter

But I thought China has implemented the raft construction with their latest submarine type 93 III.

The diameter of a submarine is a function of its pressure hull diameter and its whether the submarine is single hulled or double hulled.

A single hull submarine means the entire overall diameter of the submarine is the same diameter as its pressure hull, see below:


A double hull submarine means that the pressure hull diameter is smaller than the overall diameter of the submarine, which is the "outer hull". In the below picture, the smaller red circle is the pressure hull while the bigger yellow circle is the larger outer hull.




Now, the pressure hull of a submarine is the determinant of the amount of machinery, insulation and equipment and living space you can put into the main body of a submarine as a general rule of thumb (though one may argue some exceptions exist like Oscar class SSGN or the entire design of the Typhoon SSBN -- but let's ignore those for now).
In other words, if you want to put more machinery/insulation/etc into a submarine, you need a larger pressure hull.



So, let's say you have two different SSNs, both with a hull diameter of 10 meters.
One of these SSNs is single hulled, the other is double hulled.

The single hull SSN with a 10m diameter has a 10m pressure hull to work with to put all of its machinery and insulation into.

The double hull SSN with a 10m diameter has a pressure hull which is smaller than 10m, because the 10m diameter hull is merely the outer hull and not the pressure hull. For the double hull SSN, its actual pressure hull diameter is almost definitely going to be significantly smaller than 10m, usually up to 80% at most. That means the double hull SSN with a 10m diameter in reality only has a 8m pressure hull to put its machinery and insulation into.



09III is a double hulled submarine. Public info estimates its overall diameter at 11m -- meaning its pressure hull is likely 8.5-9m.

Everyone agrees that the pressure hull of 09V will be bigger than 09III, the question is not about the specifics of what kind of additional equipment or insulation it may have -- but rather it is important to first talk about what kind of hulled submarine it is.

If 09V is a single hulled or hybrid hulled submarine -- then it can likely retain the same overall diameter of 11m or so, but its actual pressure hull will be larger, perhaps as big as 11m in parts of the submarine.

OTOH, if 09V is double hulled, then if they they want to have a larger pressure hull diameter, that means the overall diameter (outer hull) of the submarine will have to increase as well. That is why the Akula SSN (for example) has such a massive overall diameter of 13.6m, because it has a larger outer hull to accommodate a larger pressure hull compared to previous Soviet/Russian SSNs.


The reason this is relevant is because the new Bohai facility's SSN rail gauge is 7.34m, and the width of each of the slots corresponding to the 7.34m rail gauge is only 22.5m wide.
If you're building a 13m diameter submarine, a rail gauge of 7.34m might be a bit small to support a submarine and cradle of that width (I think 12m might be at the upper limit) --- but more importantly, a 22.5m width slot means building a 13m diameter in that slot will not have enough clearance on either side of the submarine for effective construction to occur.


That is the reason I am skeptical to Chris Carlson's idea that 09V will have an overall diameter that is as big as Akula's, because...
1. He seems to believe that 09V will be double hull, whereas rumours have suggested it will likely be single or at least hybrid hulled.
2. He doesn't acknowledge that the rail gauge of 7.34m and corresponding construction slot of 22.5m width is likely far too small to build a 13+ meter wide submarine.



This is a useful starter article to read WRT single and double hulls (again, from HI Sutton, whose Covert Shores website is where his best work is rather than his articles on Forbes imho), and the source of the above two pictures:
Please, Log in or Register to view URLs content!



========


Thanks for the response @Bltizo. What do you think of Sutton's assertion that 09-V is not likely to use a pump-jet propulsor? @by78 posted some scientific studies of various pump jets; given that the work was published in 2016 (and I presume held under a publishing embargo for some time), I feel that China has had enough time and experience with this design to field it on the Type 09-V/VI - do you agree?

Also, do you think the Type 09-V/VI will have full electric propulsion?
I wouldn't put too much stock into the specifics of the depiction -- it is as speculative as we are, and likely less accurate than our rumours.
 

Hendrik_2000

Brigadier
  • Thread Starter Thread Starter
  • #518
But you are putting the cart in front of the horse and not the other way around. In order to put in all those anti vibration raft and the associated mechanism and damper, you need much bigger diameter than 10 or 11 m hull. That is design requirement there is no bargaining in it.
Looking at the cross section of the those sub It is cramp as hell there is no way you can fit in those anti vibration raft in 10 or 11 m diameter hull

Whether they design double or single hull it is irrelevant It all depend on the strength of Chinese metallurgy and how advanced they are in producing high strength steel . China design the sub with double hull following Russian practice But I think they can drop that practice now that their steel industry can produced high strength steel

Rail gauge should not be the limiting choice since they can support the carriage with large overhang
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Registered Member
But you are putting the cart in front of the horse and not the other way around. In order to put in all those anti vibration raft and the associated mechanism and damper, you need much bigger diameter than 10 or 11 m hull. That is design requirement there is no bargaining in it.
Looking at the cross section of the those sub It is cramp as hell there is no way you can fit in those anti vibration raft in 10 or 11 m diameter hull

No... Dampening rafts are not inherently massive.
You can have large rafts and small rafts depending on how big the submarine and its pressure hull diameter is.

There's nothing stopping a double hull submarine have rafting inside it's pressure hull or inside a single hull submarine.

E.g. western SSNs with pressure hull diameters of 10-11 diameter have had rafting for years, and even smaller diesel electrics have had rafting as well.
And Russian and chinese submarines that are double hulled with smaller pressure hull diameters also have rafting -- none of this is brand new all or nothing technology.


Again, another useful article from covert shores on the topic:
Please, Log in or Register to view URLs content!




-------

And yes, the rail gauge and the width of the construction slot is a limiting factors because you need to actually assemble the submarine in the surface of the construction hall and the width of the construction hall is ultimately still limited to 22.5m for each 7.34m rail gauge.


My overall point is that rafting is not a new technology, and you don't need a massive 13m+ pressure hull to accommodate rafting.
Instead, it is the pressure hull diameter that will determine the extent of rafting and insulation and equipment that a submarine can enjoy.
 
Last edited:

Tirdent

Junior Member
Registered Member
Between single/hybrid and double hulls, which is more technologically advanced?
Yes.

:D

Seriously though, it's largely a question of philosophy, each has its own set of advantages and drawbacks. Depending on the circumstances which you happen to be operating under, these will cause you to chose one or the other approach as more suitable. You can build submarines of equivalent capability either way, merely the trade-offs to get there will be different.

Very generally speaking, a single hull sub is liable to end up cheaper, all other things equal (it's going to be smaller for the same interior volume, therefore require less power to attain the same speed and take less material and fewer man hours to build). On the other hand, double (or even multi) hull gives you a couple of additional degrees of freedom in configuration which might facilitate more creative solutions to certain problems. You are not going to build a single-hull Typhoon class (non-circular external cross section).

That means the double hull SSN with a 10m diameter in reality only has a 8m pressure hull to put its machinery and insulation into.
One thing which slightly mitigates this difference is that the stiffening frames on double hull subs can be (and generally are) external to the pressure hull (i.e. inside the space between outer and inner hulls). This frees up some room inside, i.e. if we compare single and double hull subs with the same *pressure* hull diameter rather than the same overall hull diameter, the double hull will effectively have a slightly larger usable diameter. Nowhere near enough to fully compensate for the outer hull in the comparison you made, but it helps a little.

Whether they design double or single hull it is irrelevant It all depend on the strength of Chinese metallurgy and how advanced they are in producing high strength steel . China design the sub with double hull following Russian practice But I think they can drop that practice now that their steel industry can produced high strength steel
Strength of the hull material is irrelevant to the question of double vs. single hull - the outer hull on a double hull submarine is merely a hydrodynamic fairing which contributes nothing to bearing the pressure loads. Russian submarine steel formulations are among the strongest in use anywhere (along with French).
 
Last edited:

Top