Low Profile Landing Craft (LPLC)

covert_shores

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Admission: I am directly involved in this project, which will be obvious from the illustrations. Happy to discuss {most} of the details.

Also at http://www.hisutton.com/LP-LC.html


Low Profile Landing Craft


It used to be the case that operating at night was enough to give professional operators the advantage over irregular and conscript forces. But the proliferation of surveillance and targeting technology, often paired with medium anti-tank missiles, has started to close that chapter. Therefore the Low Profile Landing Craft (LP-LC) incorporates signature reducing features in the infrared, radar, visual, acoustic and electronic warfare spectrums.
gxLAB58.jpg


Unlike the high speed surface vessels often used by Special Forces the LP-LC presents a minimal profile as it creeps towards the enemy coast trimmed down with sea water ballast. And unlike stealthier Swimmer Delivery Vehicles (SDVs) the dry interior ensures that the teams disembark combat-ready. And of course it is at near-atmospheric pressure so there will be no need for decompression as the teams transfer ashore or to other vessels.

The LP-LC addresses limitations of current special forces surface and subsurface craft. It is the result of discussions with NATO units who are considering more discrete means of landing forces in medium/high risk environments. The requirement covers several roles:

  • Insertion and extraction of Special Forces for recce and cross-beach missions
  • Landing of Special Forces or commando forces (Marines/ Naval Infantry) for recce and raiding in support of amphibious operations. This includes neutralization of enemy air defenses and other high-threat systems in the immediate vicinity of the landing beach
  • Inshore ISR (Intelligence, Surveillance and Reconnaissance) missions
  • Certain counter-terrorism (CT) missions

Dl2UzFN.jpg


The top-tier of maritime orientated Special Forces are able to deploy covertly from submerged submarines. This the pinnacle of Special Forces capabilities. It is at the same time a compromise for both the Special Forces units and the submarine involved. Therefore the current trend towards Special Forces surface vessels is partly driven by the desire to free the Special Units and the submarines from each other. Additionally they are accessible to countries with insufficient submarines (or none), and to units which do not have the time or resources to operationalize complex underwater capabilities. And they have many other advantages including independent shore-to-shore capabilities, and being crewed by the unit in question or aligned specialist units (e.g. Marines or Special Boat Units). The disadvantage of course is that surface vessels are much less discrete than divers and SDVs (Swimmer Delivery Vehicles) deployed by host submarines.

There exists a sweet spot between Special Forces surface craft and SDVs. Inherently stealthier than the former, and cheaper, more flexible and operationally simpler than the latter. Enter the LP-LC.

DZczX8x.jpg


The interior is at near-atmospheric pressure so no decompression is required when the teams transfer ashore or to other vessels. The LP-LC can approach to within swimming distance of the shore, and powered inflatable boats, kayaks or DPVs (Diver Propulsion Vehicles) can be launched from the stern. It is an ideal platform for UUVs (Unmanned Underwater Vehicles) and UAVs (Unmanned Air Vehicles).

There are a number of clear advantages for the LP-LC relative to SDVs and midget subs. A single LP-LC can land or recover up to 14 persons, far in excess of SDVs. And multiple LP-LCs can operate together to support a larger force. Passengers need minimum training compared to SDVs and midget subs, making the LP-LC suitable for a greater range of missions than more specialist craft. And during extraction, the teams can be debriefed and rested before reaching home. Vitally, basic medical care can be carried out onboard.

Mechanical and electrical simplicity translates into much better safety margins than true submersibles. Maintenance is largely similar to other small surface vessels with only the military comms/sensors and plumbing systems requiring specialist skills.

EG9OTlz.jpg


The LP-LC is designed with the practicalities of operations in mind; the spacious interior provides ample room for 14 PAX with hot-bunking, mess and operations space for multi-day missions as required. The guiding principle is that the internal space should be highly configurable, allowing operators sufficient rest and comfort for extended operation. This is in stark contrast to SDVs and most Special Operations surface craft. There is sufficient headroom for passengers to move around without crouching, a major factor in operator fatigue. Amenities such as sink, microwave, pump toilet and table with similar dimensions to those in cabin yachts can be installed. The separate Operations Space allows part of the contingent to be planning, eating or preparing gear while others are resting in the forward compartment. While the Operations Space is ideal for dressing divers and packing and checking kit.
qRWbdGH.jpg


The slow and stealthy mission profile removes the complexity of incorporating a high-speed surface-planning hull. Therefore the entire mission can be conducted while running awash to minimize the risk of detection. Multiple folding masts and snort systems are carried beside the working deck.
saR0Uac.jpg
 

sferrin

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It's only a matter of time before full size surface units are doing the same. (And you thought Zumwalts were expensive.)
 

covert_shores

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Do you mean semi-sub technology on full size warships? It's a very interesting proposition but it might be that this type of approach doesn't scale, or at least it becomes a route of diminishing returns as the boat gets bigger.
 

sferrin

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covert_shores said:
Do you mean semi-sub technology on full size warships? It's a very interesting proposition but it might be that this type of approach doesn't scale, or at least it becomes a route of diminishing returns as the boat gets bigger.

Not sure if it would scale or not (could probably be made to work since we're not talking about submarine depths). Just thinking it would make it a more difficult target for ASMs as well as harder to detect.
 

Matt R.

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sferrin said:
covert_shores said:
Do you mean semi-sub technology on full size warships? It's a very interesting proposition but it might be that this type of approach doesn't scale, or at least it becomes a route of diminishing returns as the boat gets bigger.

Not sure if it would scale or not (could probably be made to work since we're not talking about submarine depths). Just thinking it would make it a more difficult target for ASMs as well as harder to detect.

That was the idea behind Rene Loire's Striker concept briefly discussed here.
 

TomS

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sferrin said:
It's only a matter of time before full size surface units are doing the same. (And you thought Zumwalts were expensive.)

Zumwalt already sort of does this -- it can ballast down to keep the tumblehome at the waterline for optimum RCS, and to improve its stability as a gun platform.
 

sferrin

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TomS said:
sferrin said:
It's only a matter of time before full size surface units are doing the same. (And you thought Zumwalts were expensive.)

Zumwalt already sort of does this -- it can ballast down to keep the tumblehome at the waterline for optimum RCS, and to improve its stability as a gun platform.

Interesting. Didn't know that.

One of the old DD-21 concepts:
 

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TomS

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Yeah, that model went around a lot back in the day, but I don't think it was a worked-out design. IIRC, it came from United Defense and was really just a platform for them to show off their gun turrets on.
 

jsport

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a genuine revolution in military affairs
 

Grey Havoc

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Matt R. said:
sferrin said:
covert_shores said:
Do you mean semi-sub technology on full size warships? It's a very interesting proposition but it might be that this type of approach doesn't scale, or at least it becomes a route of diminishing returns as the boat gets bigger.

Not sure if it would scale or not (could probably be made to work since we're not talking about submarine depths). Just thinking it would make it a more difficult target for ASMs as well as harder to detect.

That was the idea behind Rene Loire's Striker concept briefly discussed here.

Also, you may wish to have a gander at this old topic, if you haven't already come across it.
 

sferrin

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Grey Havoc said:
Matt R. said:
sferrin said:
covert_shores said:
Do you mean semi-sub technology on full size warships? It's a very interesting proposition but it might be that this type of approach doesn't scale, or at least it becomes a route of diminishing returns as the boat gets bigger.

Not sure if it would scale or not (could probably be made to work since we're not talking about submarine depths). Just thinking it would make it a more difficult target for ASMs as well as harder to detect.

That was the idea behind Rene Loire's Striker concept briefly discussed here.

Also, you may wish to have a gander at this old topic, if you haven't already come across it.

Pretty much exactly what I was thinking. Sensors out of the water and during battle, the rest under water. But on the surface the majority of the time.
 

marauder2048

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Seems like an excellent concept but I'm wondering how susceptible these semi-submersibles are to detection by OTH radars; those high-end drug runners have
been operating semi-submersibles against the US ROTHRs with mixed success.
 

covert_shores

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It's not a connection I'd like to make in an sales materials but yes, it is a lot like a narco sub. But done to military standards and with variable ballast.

Narco subs get intercepted for a number of reasons. Some best not discussed. But suffice it to say that many of those causes do not automatically translate over to LPLC. And the LPLC has its own threats to contend with than narco subs are not concerned with.

The biggest threat is MPAs. I am sure detection ranges will be much lower than a similarly sized conventional boat, but the best MPAs have some very good sensors on them so even a LPLC might be spotted. The answer to MPAs is to shoot them down with other assets. Or fight against people who don't have them.

Shore based drones are also a concern, but less so. They are more the reason for LPLC than the argument against.
 

covert_shores

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The topic of applying similar semi-sub technologies to larger boats is interesting. And challenging.

The extent to which it is above water to be a 'semi-sub' is more or less constant. So as you get bigger, the portion above water gets smaller. LPLC has about 0.6m-0.8m above water, a figure largely driven by certain payload considerations. If you scale it up to a destroyer but keep the proportions the same, then it starts getting tall again, so low profile maybe, but not really semi-submerged. Like that monitor style image of the early Zumwalt concept.

If you instead go the route of fully submerging most of the hull, and only showing a sensor and maybe weapons platform, then you are entering submarine hull design and manufacturer territory which would massively increase cost. You might as well build a real sub.
 

Foo Fighter

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What sort of sea keeping abilities would the low hull give it, I would hate to be on one of those in heavy swells/sea state.
 

covert_shores

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Foo Fighter said:
What sort of sea keeping abilities would the low hull give it, I would hate to be on one of those in heavy swells/sea state.
i dont have a definite answer I can share and anyway that's for the naval architect to determine during detailed design. ;) It's pros and cons like everything, and the ballast is variable so when it gets too scary you can ballast-up and ride it out like any other boat of that size, except that you are not a planing hull, and you are more weather proof than most equivalent designs.

For a really rough sea orientated SF interceptor, check out the Barracuda on my website.

Latest info is that we are expecting the LPLC hull design to be refined significantly in the next phase of development. Sea keeping will likely get better.
 

RP1

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Seakeeping for small low-freeboard craft is "different". At some point it becomes easier to just accept that the craft is going to have waves wash over her in some conditions. The Very Slender Vessels by Parragon Mann worked this way at speed, and there was a round the world trimaran speedboat that had a lot of shaping specifically to operate in this condition. This requires a bit more attention to watertightness, considering how to ensure the air intake to the engines, and shaping to insure she comes back up again!
 

cluttonfred

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I recently visited Gothenburg (Göteborg), Sweden, and my kids and I visited Maritiman, a floating maritime museum. One of the ships (unfortunately just a bare hull) was the John Ericsson-designed monitor Sölve built in 1875. I wonder if there might be some lessons to be learned from the history of monitor-type ships to inform these low-freeboard landing craft concepts?
 

covert_shores

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RP1 said:
Seakeeping for small low-freeboard craft is "different". At some point it becomes easier to just accept that the craft is going to have waves wash over her in some conditions. The Very Slender Vessels by Parragon Mann worked this way at speed, and there was a round the world trimaran speedboat that had a lot of shaping specifically to operate in this condition. This requires a bit more attention to watertightness, considering how to ensure the air intake to the engines, and shaping to insure she comes back up again!
oh sea water will definitely wash over the top, that's part of the motivation for being so low profile. It's a trade off, but it's about being as close to submerged as possible without having to go to the same extremes of pressure hull construction as a submarine. Exactly like a low profile narco sub in that respect. The inlets and hatches have to be appropriate. I haven't shared the relevant images but lots of thought has gone into that type of thing.
 

covert_shores

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Project update:

We are working with a Naval Architect to mature the concept. Preliminary design is very different from the concept sketches. very cool boat.
 

Grey Havoc

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This might sound like a strange question, but is it intended to be air deployable (i.e. airdropped over ocean)?
 

covert_shores

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Don't know how to answer that without saying too much. sorry.

Tangent: that's the sort of capability a lot of boat builders imply or advertise, but that very few units go to the bother or expense of qualifying. Takes a lot of testing and training = $$$. However, there are some units which do maintain that type of capability mainly with RHIBs. See http://www.hisutton.com/Exclusive%20-COMSUBINs%20elusive%20Rigid%20Inflatable%20Boat.html for a RHIB with some interesting features.
 

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Looking at the sizes of low profile vessels in use, does the scaling of the concept favor small vessels or does the scale of nacro-enterprises limit the size? If one needs to move thousands of tons to what extent would it make sense to scale up or split into more hulls?

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Thinking in alt-history terms, would such vessels would have been superior to transport submarines and warships used in ww2 naval blockade running in at cost/payload/success?
 

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