Apparently a second unit of the semi-submersible weapons ship (arsenal ship?) has been launched.
I think this has been spotted before, check posts from March 15 on this topic.
Closer views of the testing and evaluation platform ship with the 155mm gun. Posted by @欧阳振我86468 on Weibo.
Some thoughts on the Trimaran
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Primary mission
Act as an offboard carrier for 32 UVLS cells.
Observed Characteristics
63m Length
6?m Beam for the Main Hull
13m Beam including Trimaran Outriggers
The hullform looks like a fully-submerged submarine, with the addition of outriggers.
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Speculation
The UVLS specification has depths of 3.3m, 7m and 9m.
Are there even any missiles in existence that fit the 3.3m version?
So if they go with the 7m or 9m version, this would result in a tall but narrow cross-section, when compared to a circular submarine hullform.
The existence of outriggers implies a lot of time spent on the surface to help maintain stability.
The Length to Beam ratio (63/6) implies a hullform optimised for high speed, which makes sense given that it would be accompanying Destroyers at a maximum of 32? knots
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When operating with a Destroyer, there isn't any issue with the Trimaran being surfaced as it is protected by the Destroyer. So it just needs the UVLS cells and a datalink.
When under attack, the Trimaran can fire off its missiles first and then completely submerge (without snorkeling) to a depth of 20m
This should mean it is invulnerable to missiles arriving from the surface.
It can still receive commands via a tethered surface buoy.
Then it can wait out the missile attack and resurface in 5 minutes
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If we assume a normal operating depth of 20m, commercial ships already reach similar depths and even WW2 submarines were designed to operate to 100m.
A larger Type-056 with a basic fitout is probably $50-80 Mn to purchase.
We also saw the much larger and more advanced Yuan-class submarines being offered to Thailand for $300 Mn previously.
So in terms of procurement cost, the Trimaran might cost $100-150? Mn for 32 VLS Cells with minimal other weapons systems.
This is a far better procurement cost-ratio than for the Type-055 or Type-052D
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If I look at the notional dimensions, hullform and operating condition, it reminds me of the early diesel-electric submarines that were really surface vessels which could spend a limited time underwater on batteries.
The Type-IX submarine looks pretty similar in terms of dimensions.
It's listed with a maximum speed of 18 knots with 4.4MW of propulsion.
To reach 32 knots, that implies a propulsion requirement of 24MW
(If I use the larger Type-056 Corvette for comparison, to reach 32 knots implies 21MW of propulsion)
So to operate the Trimaran with 32 VLS cells at 32 knots would require about 21-24MW of engine power. (Query - Is there enough space inside the hull? If using diesel engine/generators, it would be like the four engines fitted on a Type-054A Frigate)
This would be somewhat more efficient than the Type-055 or Type-052D in terms of the required engine power to move a single VLS cell and therefore fuel consumption
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So overall, if Chinese Navy Destroyers need more VLS cells, it makes sense to buy Trimarans which have a better profile in terms of procurement cost and operating costs. In addition, the Destroyers can spend more time on station, as the Trimarans will fire off their missiles first, and then go back to port to reload instead of the Destroyer having to do this.
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When the Trimarans need to transit to/from port for reloads, they could submerge and operate at snorkel depth, so they wouldn't need necessarily need an escort. So the Trimarans could also be unmanned, which also reduces operating costs in peacetime.
In terms of equipment, the Trimaran only needs the VLS cells, datalinks, satcom, snorkel and surveillance/periscope mast. No expensive radars, sonar, guns or torpedo tubes required
However, I can see the case for an ASW variant, as a surface group would want to use the most expendable ship possible to spar with a submarine.
If the base Trimaran is about $100Mn, then they could add a Towed Array and also Variable Depth Sonar. Perhaps a bow sonar as well. They could also reduce the number of VLS cells and fill them with ASROC torpedoes. It would be much lower cost than any Destroyer or Frigate, and could be unmanned.
EDIT
Doing some back of the envelope calculations, if a ship can travel at 32knots, a Mk48 ADCAP would have to be launched within 13km (7nm) in order to have enough fuel to hit the target.
And the LLMs are saying that CAPTAS can definitely detect a nuclear submarine coated with anechoic tiles at 15km?
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