US Navy Submerged Tank Landing Ship (LSST)

Triton

Donald McKelvy
Senior Member
Joined
Aug 14, 2009
Messages
9,719
Reaction score
971
Website
deeptowild.blogspot.com
The submerged tank landing ship (LSST) was sketched in 1955 by the United States Navy's Bureau of Ships (BuShips) for its "dream book." Powered by an S5W nuclear reactor, it would have attained 16 knots in landing trim and 12 knots submerged. It would have carried 500 troops and 500 tons of cargo, at a unit price of $85 million. The four-level arrangement provided two levels for troop berthing and messing, with the control room/attack center and ship's officers on the upper level (but with troop berths at the fore end of the upper level,) and stores and fresh water on the lowest level. Compensating tanks are shown at the fore end. The LSST could have beached at a keel slope of 1:50.

General Characteristics

Length: 565 ft.
Beam (maximum): 81 ft.
Light displacement: 8,000 tons
Surfaced displacement: 8,700 tons
Submerged displacement: 26,000 tons
SHP: 15,000
Surfaced speed: 16 kts.
Submerged speed: 12 kts.
Torpedo tubes: 2
Payload: 500 tons
Cost: $85 million

Source: US Submarines Since 1945: An Illustrated Design History by Norman Friedman, US Naval Institute, 1994.
 

Attachments

  • BuShipsLSST1955.JPG
    BuShipsLSST1955.JPG
    24.1 KB · Views: 1,949

RyanC

Crazy Researcher
Top Contributor
Senior Member
Joined
Dec 19, 2006
Messages
884
Reaction score
254
Website
www.alternatewars.com
From USN Photo Archives in the Yard.
 

Attachments

  • LSST Painting at NHHC-Photo Archives.jpg
    LSST Painting at NHHC-Photo Archives.jpg
    413.4 KB · Views: 1,782

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,878
Reaction score
2,389
It was pretty much a concept in search of a mission. The sort of small scale raiding such a vessel would allow didn't prove terribly useful in WW2 and wasn't looking much better in the 1950s.

Plus, planners were probably not ecstatic about any concept that called for beaching a ship with a nuclear reactor.
 

Grey Havoc

ACCESS: USAP
Senior Member
Joined
Oct 9, 2009
Messages
16,702
Reaction score
6,255
TomS said:
It was pretty much a concept in search of a mission. The sort of small scale raiding such a vessel would allow didn't prove terribly useful in WW2 and wasn't looking much better in the 1950s.

Oh, I think the Force Recon (USMC) for one would have found a fair few uses for it!
 

airman

ACCESS: Top Secret
Joined
Oct 14, 2007
Messages
1,297
Reaction score
145
Website
zeef.com
Grey Havoc said:
TomS said:
It was pretty much a concept in search of a mission. The sort of small scale raiding such a vessel would allow didn't prove terribly useful in WW2 and wasn't looking much better in the 1950s.

Oh, I think the Force Recon (USMC) for one would have found a fair few uses for it!
So the cost of unit : 85milion of dollars in 1950s i don't think was nuts !
 

Graham1973

ACCESS: Top Secret
Senior Member
Joined
Dec 16, 2010
Messages
1,802
Reaction score
625
Interesting. I'd seen a similar concept in a late '80s techno-thriller called Silent Hunter (Charles D. Taylor). His USS Imperator is a highly automated vessel designed to transport a complete Marine Expeditionary Unit (including helicopters!).
 

Sea Skimmer

ACCESS: Secret
Senior Member
Joined
Jul 13, 2008
Messages
394
Reaction score
56
TomS said:
It was pretty much a concept in search of a mission. The sort of small scale raiding such a vessel would allow didn't prove terribly useful in WW2 and wasn't looking much better in the 1950s.

Plus, planners were probably not ecstatic about any concept that called for beaching a ship with a nuclear reactor.

Small scale raiding would work a lot better in terms of taking on large important objectives if you gave the landing force nuclear artillery, as would only be expected in the 1950s. Of course then one might ask why not simply fire a nuclear missile at the enemy, but war planning in the 1950s often assumed that strategic nuclear warfare would not bring about a total halt to all other fighting. Certainly one submarine landing 200 men with nuclear howitzers is a lot less exposed then even a single surface ship to nuclear attack.

I do recall though that the Soviets ended up approving a similar class for construction, Project 917 I think it was, which was not built only because the shipyard was too busy on other projects. For the USSR raiding would make more sense, since the US had so many near totally undefended outposts as communications/spacetracking/SOSUS facilities around the world.
 

Abraham Gubler

ACCESS: Top Secret
Senior Member
Joined
Mar 18, 2008
Messages
3,555
Reaction score
306
I think you will all find that raiding was a secondary mission for a submarine LST. The primary role was to land a first wave of an amphibious assault by surprise. That way combat units could be up the beach before the defender's coastal artillery and beach defences were activated. This is a response to all the amphibious expereince of WWII where heavy casulties were suffered thanks to active beach defences. Before the development of the helicopter a submerged assault was an options contender.
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,878
Reaction score
2,389
It's not that clear-cut, to be honest. When the Marines proposed the idea of submarine landing ships around 1950 (in non-nuclear form) they explicitly called for them to replace APDs in the raiding role. (See Friedman's history of Amphibious Warfare ships, for example). When BuShips proposed it again in 1955, it's not clear what idea they had in mind, other than possible dispersal in the face of nuclear threats -- the "dream book" was mostly about technological possibilities, not operational concepts. By that time, the Marines were already well along in developing doctrine for vertical envelopment by helicopter (having experimented with it in Korea), so I doubt anyone was seriously considering the submarine option.
 

Sea Skimmer

ACCESS: Secret
Senior Member
Joined
Jul 13, 2008
Messages
394
Reaction score
56
No, not at all as far as a submarine transport goes. Either you destroy the threats, or you are destroyed unloading on the beach anyway. A submarine which cannot carry large numbers of transport aircraft, which decouple the location of both the landing force and the amphibious force from a specific point of beach would make the situation much worse, not better. It'd also have few if any self defenses, and any it did mount would be immensely expensive additions. You could easily be talking about an eight or ten billion dollar sub to do part of the job of an LPD-17. It makes more sense to spend the money on more escorts and air power.


Small submarine landing craft might have some use for raiding, but then stuff like the Advanced SEAL delivery vehicle already exist for this purpose, and have proven immensely expensive themselves.
 

BAROBA

3D artist
Joined
Jul 6, 2007
Messages
342
Reaction score
22
Website
www.baroba.be
About being destroyed on the beach...
That is why it would make sense to unload tanks onto a beach. Most coastal defenses are not suited for killing tanks only for defense against infanterie. Tank defenses are usually positioned more inland. The tanks could set up a beachhead quicker. You could even land a few plow-tanks that would clear a beachmine field.
But wouldn't it make more sense to unload the tanks underwater? Wouldn't it be cheaper to make a tank watertight and transport them close to a beach and unload there? Aren't tanks airtight already because of the ABC-protection they have?
But I think these landingsubs would quickly have lost they usefulness after the cold war was over. Which beaches in the world are still heavily defended? Anyone knows?


Just a tought...

Rob

Sea Skimmer said:
No, not at all as far as a submarine transport goes. Either you destroy the threats, or you are destroyed unloading on the beach anyway. A submarine which cannot carry large numbers of transport aircraft, which decouple the location of both the landing force and the amphibious force from a specific point of beach would make the situation much worse, not better. It'd also have few if any self defenses, and any it did mount would be immensely expensive additions. You could easily be talking about an eight or ten billion dollar sub to do part of the job of an LPD-17. It makes more sense to spend the money on more escorts and air power.


Small submarine landing craft might have some use for raiding, but then stuff like the Advanced SEAL delivery vehicle already exist for this purpose, and have proven immensely expensive themselves.
 

Sea Skimmer

ACCESS: Secret
Senior Member
Joined
Jul 13, 2008
Messages
394
Reaction score
56
BAROBA said:
About being destroyed on the beach...
That is why it would make sense to unload tanks onto a beach. Most coastal defenses are not suited for killing tanks only for defense against infanterie. Tank defenses are usually positioned more inland.


That has zero basis in historical fact or anything approaching military reality, I'd love to know what basis you use for such a sweeping generalization that the enemy will be completely incompetent and in complete ignorance of the already existing need to attack landing craft or amtracks? In fact about the single most likely dedicated invasion defense is anti vehicle mines at the waters edge and shallow water, followed by anti tank missiles covering the water approaches. Of course a tank crawling ashore with no support is vulnerable to just about everything anyway.



The tanks could set up a beachhead quicker. You could even land a few plow-tanks that would clear a beachmine field.


Not if mines are laid in shallow water, and many such anti invasion mines exist and are stockpiled all over the world. Nobody has ever come up with a good solution to mines laid in 5-10ft of water, the current USMC plan is to bomb them and wait for the surf to fill the craters in with more sand. Feasible, but not quick or covert, or usable from a submarine. Life is much easier if you secure inland first from the air and then worry about mine clearing. Thus ever more emphasis on air assault in amphibious warfare ships designs all around the world.


But wouldn't it make more sense to unload the tanks underwater? Wouldn't it be cheaper to make a tank watertight and transport them close to a beach and unload there? Aren't tanks airtight already because of the ABC-protection they have?


No in fact tanks leak air like crazy, which is why they use an over pressure system to make sure the air only leaks out. You would need very serious mods to make a modern tank capable of deploying underwater from a submarine, and it'd still be a terrible and terribly limited idea operationally.
 

BAROBA

3D artist
Joined
Jul 6, 2007
Messages
342
Reaction score
22
Website
www.baroba.be
Hi Sea skimmer,

I confess, I am not a professional, just an amateur who finds LSST an interesting idea.
1. Most modern wars were pretty much asymmetric, where on bigger ( for example the US) invade a smaller less capable country.
Somalia, Iraq, Panama,.... Those all had beaches and -correct me if I am wrong- none of them were mined. So there the idea could work..

2. That would pretty much ruin every tank driving onto land.
But in an asymmetric war...

3. That idea is finally sunk....Unless we go the unmanned route... A submarine snorkel can be used to command the unmanned tank drones on land, or via wire underwater.

@Seaskimmer, do you have some more insight into this matter then me? Technical skills?
Let me know :)

Rob


Sea Skimmer said:
BAROBA said:
About being destroyed on the beach...
That is why it would make sense to unload tanks onto a beach. Most coastal defenses are not suited for killing tanks only for defense against infanterie. Tank defenses are usually positioned more inland.


1.That has zero basis in historical fact or anything approaching military reality, I'd love to know what basis you use for such a sweeping generalization that the enemy will be completely incompetent and in complete ignorance of the already existing need to attack landing craft or amtracks? In fact about the single most likely dedicated invasion defense is anti vehicle mines at the waters edge and shallow water, followed by anti tank missiles covering the water approaches. Of course a tank crawling ashore with no support is vulnerable to just about everything anyway.



The tanks could set up a beachhead quicker. You could even land a few plow-tanks that would clear a beachmine field.


2.Not if mines are laid in shallow water, and many such anti invasion mines exist and are stockpiled all over the world. Nobody has ever come up with a good solution to mines laid in 5-10ft of water, the current USMC plan is to bomb them and wait for the surf to fill the craters in with more sand. Feasible, but not quick or covert, or usable from a submarine. Life is much easier if you secure inland first from the air and then worry about mine clearing. Thus ever more emphasis on air assault in amphibious warfare ships designs all around the world.


But wouldn't it make more sense to unload the tanks underwater? Wouldn't it be cheaper to make a tank watertight and transport them close to a beach and unload there? Aren't tanks airtight already because of the ABC-protection they have?


No in fact tanks leak air like crazy, which is why they use an over pressure system to make sure the air only leaks out. You would need very serious mods to make a modern tank capable of deploying underwater from a submarine, and it'd still be a terrible and terribly limited idea operationally.
 

covert_shores

Research + illustration
Senior Member
Joined
Oct 31, 2014
Messages
715
Reaction score
232
Website
www.hisutton.com
Interesting thread (thanks for pointing me to it).

I suspect that part of its failureto materialize was that large subs were jealously defended USN territory and their priorities were nuclear deterrence and hunter-killers. They had no interest in amphibious operations really. The US x-craft, which were intended for beach recce, suffered a similar fate around that time, although one was built (USS-X1).

The marines and UDT did get transport subs though, USS Sealion and USS Perch. Proved their worth in Korea but never invested in relative to other submarine capabilities.
 

athpilot

Fly me to the moon...
Joined
Nov 18, 2012
Messages
319
Reaction score
174
For the soviet counterpart see:
http://www.secretprojects.co.uk/forum/index.php/topic,8288.0.html
 

athpilot

Fly me to the moon...
Joined
Nov 18, 2012
Messages
319
Reaction score
174
Offtopic: Hi covert-shores! Is covertshores.blogspot.com your blog? It´s very interesting!
Greetings
Athpilot
 

Similar threads

Top