Friday, January 30, 2015

Wither the Well Deck?

WWII saw the development of the attack transport (APA) with landing craft being carried, launched, and loaded over the side of the ship.   More recently, post-war development has seen the development of the well deck, a flooded space in the stern of the ship from which landing craft (the term being used generically to include any type of landing craft or connector) could load and launch. 

The well deck was, perhaps, mechanically simpler than the APA approach and allowed for easier loading but suffers from a significantly reduced number of landing craft.  The reduced number was supposedly compensated for by the individual landing craft being some combination of bigger and faster.  Setting aside the actual capacity and throughput, the weakness in this approach is that there is no allowance for attrition of the landing craft (see, "Amphibious Assault Attrition").  When a ship carries only two or three LCACs, for example, the loss of even one has a near catastrophic impact on the follow-on landings and, more importantly, sustainment phase.

So, given the above weakness, you’d guess that the trend is towards larger well decks that can carry and operate more landing craft, right?  Oddly, you’d be wrong.  Well decks are becoming fewer and smaller.

Here are the well deck dimensions for recent classes of amphibious ships.

From oldest to newest,

Tarawa LHA-1                       268’ x 78’
Wasp LHD-1                         267’ x 50’
America LHA-6                     none

Again, from oldest to newest,

Whidbey Island LSD-41        440’ x 50’
Harpers Ferry LSD-49          220’ x 50’
San Antonio LPD-17            170’ x 50’

What jumps out from a cursory examination is that the recent amphibious ships have fewer and smaller well decks.  Indeed, the first two members of the America class LHA have no well deck.  The LPD-17 has a significantly smaller well deck than its predecessors.  What’s particularly disturbing about the LPD-17 is that it is likely to be the basis for the next generation amphibious ship, the LX(R) which is intended as a replacement for the Whidbey Island and Harpers Ferry classes.  If that happens, that will be a LOT of lost well deck space.

There is only one way to get large quantities of supplies, tanks, and heavy equipment ashore and that is via ship/landing craft.  As the well decks disappear and get smaller, there are fewer and fewer LCACs available to the ARG/MEU.  How do the Marines/Navy think those supplies and heavy equipment will get ashore?  I’m baffled by their thinking.

There is, of course, one reasonable explanation that fits the facts.  The Marines are abandoning the amphibious assault mission in favor of vertical assault.  Consider recent evidence:

  • The new LHA was built with no well deck.
  • The LPD-17 has a significantly smaller well deck than its predecessors.
  • AGR/MEU LCAC numbers are shrinking.
  • The Marines are shedding tanks, artillery, and heavy equipment.
  • The Marines have committed fully to the MV-22.
  • The Marines have indefinitely deferred an AAV replacement.

The simplest explanation that fits the facts is invariably the correct one.

The simplest explanation is that the Marines are getting out of the amphibious assault business and becoming an expeditionary air force and aviation assault force.

What do we hear from the Marines?  Are they talking about becoming more powerful?  Are they talking about beefing up to be able to knock down the Chinese door?  No.  They are talking about becoming lighter and more mobile.  They are talking about being a crisis response force and humanitarian relief organization.

Back to the well deck, itself.  Is it needed?  If we’re going to do amphibious assaults then it, or something functionally equivalent, is needed.  It’s just not possible to conduct and sustain an assault using purely or mainly aviation assets.  We need the ability to transport heavy loads to the landing site and landing craft (in the generic sense) are the only viable option.  Now, we don’t necessarily have to use well decks.  We can use the old WWII APA and landing craft approach, modern LSTs, or something similar.  The point is, we need some means to place heavy loads on landing craft and a well deck is certainly a convenient means to do so. 

This discussion goes back to the need for a broad military strategy.  Do we, as a nation and a military, see the need to be able to conduct large amphibious assaults?  If so, we’re trending in the wrong direction when it comes to amphibious ship design.  If we don’t see a need, then we need to re-examine our entire amphibious force structure.

Well decks are a symptom and a bottleneck when it comes to amphibious assaults and the Navy/Marines need to come to grips with the broader issue and choose a logical path based on an overall strategy.  Failure to do so will see amphibious assault slowly wither away as it falls prey to the short term budgetary consequences of the latest “shiny toy” acquisitions approach currently in vogue. 

An AAV replacement gets indefinitely deferred ... 
LSTs are retired with no replacement …
Well decks shrink or vanish ... 
Tanks and heavy equipment are cut …
Doctrine moves assault ships further and further offshore ... 

Before you know it, no more amphibious assault capability. 

Well decks are the canary in the amphibious coal mine and right now the well deck canaries are dying.  Well decks are telling us what’s happening but is this what we want to happen?


  1. The horrible irony being any serious disaster response requires over the beach logistics.

  2. This comment has been removed by the author.

    1. Smitty, nice background article. Hadn't seen it. Thanks for the link.

      YMMV? I don't know that one?

      The America class is intriguing as far as why the first two were built without a well deck. It's not like they built the ship and then discovered that it didn't have a well deck. They knew all too well that it didn't have a well deck and what that meant and yet, for reasons that have not been articulated, thought that was a good thing. I wonder what about that design was appealing? My personal theory is that when the ship was designed, the Navy was still hoping that the F-35B would be a major success (and affordable) and they could get a "cheap", small carrier on the sly. In fact, I suspect the America may have been envisioned as the prototype of a class of small carrier. However, once it became obvious that the F-35B wouldn't be cheap and probably wouldn't be affordable in sufficient numbers, they reverted to the traditional well deck. Just a theory. I'd sure like to know what the real rationale was.

    2. "Comparing LPD-17 with the older LSDs is a bit of apples to oranges. A better comparison would be the LSDs to the new LX(R) requirements."

      The LX(R) will be a modified LPD-17, hence the comparison is perfectly valid unless I'm missing your point. The LX(R)(LPD-17) will be the future common amphibious ship and will have the same very small well deck that the LPD-17 has unless the LPD-17 is so drastically redesigned and resized that it's not really an LPD-17 derivative anymore and that seems highly unlikely.

      The Navy/Marines are getting out of the well deck business. That's not necessarily bad if they replace the capability with an APA or LST or LCU or whatever. However, we're cutting well deck capacity with no corresponding addition of alternate capability. Thus, we're creating a landing capacity shortfall.

    3. ELCAS-M/JLOTS takes &+ days to build, and operations are limited to Sea State 2.

      Worse, the maximum pier depth is 6.1 meters at the pier head, which is bloody shallow for any military or commercial cargo ship.

      Worse still, max throughput of ELCAS-M/JLOTS is 5 containers per hour (often less). A standard 40’ intermodal container holds ~26 metric tons.

      Worse of all, ELCAS-M/JLOTS does not support the direct offload of either MSC or commercial hulls!

      Five containers per hour is 130 tons. 24 hours means the max theoretical throughput of ELCAS/JLOTS is 120 containers per day or 3,120 tons of cargo per 24 hour day. But real throughput will be much lower because sea state will interfere with operations, and most ships physically will be unable to offload, meaning the cargo will have to be moved by causeways and smaller vessels like LCUs.

      Officially a MEU (one reinforced USMC rifle battalion), will consume about 650 tons of logistics a day. This is a vastly understated number based on using HMMWVs, not MRAPs or JLTV which a bigger and thirstier, does not allow for the fact that men in combat have historically use ammunition at 3x the rate generally planned for in peace time.

      During the Haiti earthquakes, a massive surge of military and commercial aircraft managed to deliver about 15,000 tons of cargo in five a(5) days. A single RORO barge the American Trader delivered over 6,000 tons of cargo in a single day. Think Defense ran a great series


      Just a few fi

    4. Smitty
      Very true
      But repairing a port via amphib is a lot easier than doing it via helicopter

    5. Well, with lcacs and mexafloats you can run in a steady stream of heavy equipment and material, D9s and truckloads of cement.
      Helicopter, not so much.
      If the ports totalled you might need proper dredgers and mobile sea walls, but with a few dozers you can probably clear a slipway and some hard standing

    6. TrT,
      causeways (mexafloats) and other craft can indeed run a lot of material back and forth, but they are nothing compared to a proper port.

      Also under represented are the pipelines for water, fuel, and maybe cement!


    7. Smitty yes to Freidman's article, and to your latter point, any translation to JLOTS will probably NOT involve the amphibs because they will be GONE from the scene. MSC and other sealift ships will as usual lift in the tons of materials needed for DR/HA

  3. I think this is all starting to tie together.

    YES USMC is switching to airborne assault as its primary method. I agree.

    The have already said they aren’t “into” opposed amphibious landings any more.
    Attrition will occur mainly in any seriously opposed landing. If you can create a beachhead via airborne means, perhaps they think landing craft will not be lost, or at least not in serious numbers.

    In airborne assault you will only need anphibs for sustainment.

    And the final piece of the puzzle.
    THAT does allow you to keep the fleet at 50nm from shore. Which of course USN have stated.

    Also you can have large ships with a higher percentage of hull devoted to storage of equipment rather than well deck and transport of supplies.

    It’s a little pipe dream though isn’t it. Eggs in 1 basket etc etc

    Better to be full spectrum, it’s much more difficult to defend against.

    In this case enemies can concentrate on distributed MANPADS and foil the entire assault.


    1. "In airborne assault you will only need anphibs for sustainment."


      To support any serious land operations over a protracted period, you have to have a sea port.

      To support even modest land operations, you need an over the beach capacity for feul and ammunition (water?).


  4. Here’s a kooky idea for getting heavy vehicles inland quickly, from a ship out of range of shore defenses. No well deck needed.

    1. Helos / V-22s carry Marines (including vehicle crews) to secure a landing zone inland

    2. Heavy-lift helo or airship lifts armored vehicle from deck of ship to a specified altitude

    3. Vehicle glides beneath a giant ram-air parachute, steered autonomously. A ducted fan propulsor powered by the vehicle’s engine (via electrical or mechanical accessory drive) provides enough thrust for sustained flight.

    4. Vehicle flies itself to LZ and lands. Crew removes parachute and ducted fan, and drives off.

    Not sure how feasible this is (e.g. how big would ram-air parachute need to be), but it's fun to imagine.


    1. BTL, I would think such a flying vehicle would make a very large, non-stealthy, and enticing target but, regardless, I give you full marks for creative thinking!!!

      Whether this particular idea is workable and survivable or not, this is the kind of outside the box thinking that the military needs to engage in because we currently have no good ideas for getting heavy equipment ashore in an opposed landing scenario.

      I enjoyed your comment! Keep writing.

  5. The Corps isn't, but the leadership certainly was. And as with many problems in the entire DoD, it goes back again to jumping into counter-insurgency wth both feet, forgetting conventional warfare. No amphibs needed for counter terrorism if the USMC is just a coin force.. Or ASW frigates and MCM ships just gunboats (LCS) to shoot swarm boats and connectors (JHSV, MLP, etc) for resupply. The USMC is getting updated LCAC replacements but not AAVs. The whole 60 mile thing is based on something that sounds reasonable and about protecting the troops...but how is putting half as many (Only so many MV22s to go around) purely infantry troops without armored support...MV-22s can't carry armor like an LCM...on a beach safer? So the 60 mile limit is to protect them from missiles...are MV-22s invisible to missiles? Probably not. And there would be less MV-22s in a pure air-assault than there would be AAVs in a full on amphib invasion, so less targets to shoot at. And yes, an APD can get hit by missiles...but the LHA launching the MV-22 is invulnerable once they get 60 miles away? There's not enemy missiles with more than a 60 mile range or no enemy subs or frigates that can't fire offshore and hit them?
    An air-assault is just as vulnerable as an amphib in an A2/AD situation...but more useful than Amphib in COIN ops....the USMC leadership all want to be big bad spec-ops fighting ISIS not grunts having to take back an island from China or invade Iran, or anything that sounds remotely like conventional war.
    That may change with new leadership at the top of USMC...or not.
    Mark my words, at this rate in another 10 years the Navy will be nothing but air-support for COIN focused marines and a source of personnel for SEAL recruitment.

  6. CNO you need to add this to your bullets:
    The CH-53K program is late and another expensive aircraft procurement

  7. CNO the problem is NOT so much HOW to load up the heavy cargo on landing craft, it is where does the USMC expect to get enough of them, and HOW are they to be lifted to the AOA?
    The answer to the latter is a REAL Flo/Flo (not the MLP POS) which could lift six SSC easily. The cargo of course would be on whatever amphib is there.
    Now getting the Marines to accept a black hull in their precious ARG is something else all together~ They have barely accepted the T-AKE which WILL make a transformational difference in cargo lift IMHO.

  8. "As the well decks disappear and get smaller, there are fewer and fewer LCACs available to the ARG/MEU."

    Well deck space seemingly was never correlated 1-to-1 with LCACs actually carried. It apparently goes: Wasp (3), Tarawa (1), Anchorage (4), Austin (1), Whidbey Island (4–5), Harper's Ferry (2), and San Antonio (2). The Antonio carries more than the larger-well-deck Austin it replaced. The well deck Americas will carry 1 more LCAC than the Tarawas. The Wasp carries 2 more than the Tarawa despite being speced as having the same space.

    "The Marines are shedding tanks, artillery, and heavy equipment."

    From the actual ARGs? Are they really? Where'd you learn that?

    Anyway, regarding BTL’s powered parafoil idea: it shouldn’t require helos/airships if the ship could reach the achievably low speeds required for parafoil flight.

    1. Oh. Additionally, 91 LCACs were built and there are ~72-80 left. Assume 100% availability and the current amphib fleet could fit 94.


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