Navy Amphibious Ships

Got this in a comment on last night’s post about the USS New Orleans (LPD 18):

I still don’t understand the difference between LSDs and LHDs. In a nutshell, what’s the diff?

I’ll admit that I’m often confused about, and often confuse, all the Navy’s “L” ships. But here’s a basic rundown:

  • LSD – Landing Ship, Dock
    These ships are primarily LCAC (Landing Craft, Air Cushion – the hovercraft) platforms. They also support other small landing craft and operate a couple of helicopters. They each carry about 500 Marines. The Whidbey Island-class ships (and the cargo variant Harper’s Ferry-class ships) are the state of the art LSDs in the fleet.
  • LHD – Landing, Helicopter, Dock
    These are the “light aircraft carriers” of the fleet. They are, in fact, about the size of a WW2 Essex-class CV, and their general appearance resembles that of a standard flat top. They operate up to 40 helicopters and Harriers and carry over 2,000 Marines. They can also operate LCACs and other landing craft out of a well deck in the stern. They each, in truth, represent more seaborne military power than most nations can muster. The Wasp-class ships are the LHDs in the fleet.
  • LHA – Landing, Helicopter, Assault
    These are the predecessors to the LHDs and are, basically, smaller versions of them. They were not designed to operate LCACs, though they now do so in a limited role. They also operate other landing craft and carry about 30 helicopters and Harriers. The Tarawa-class ships are the LHAs in the fleet, but they are aging and will be replaced by they LHA(R) class in the future.
  • LPD – Landing, Platform, Dock
    The newest LPDs have been designed to replace four types of ships – older classes of LPDs, LSDs, and LSTs (Landing Ship, Tank) and the already-retired LKA (Landing, Cargo, Assault) cargo ships. They’re basically “LSDs on steroids”, and operate a couple of LCACs and four or so helicopters or V-22 Ospreys. They carry about 700 Marines. The San Antonio-class ships are just entering service, replacing the Austin-class LPDs.

Here, to compare LSDs and LHDs, are a couple of pics:


USS Oak Hill (LSD-51)


USS Kearsarge (LHD-3)
(Click each for a better look)

In practice, you will usually see a number of various amphibious assault ships operating together. For instance, a typical Expeditionary Strike Group is centered on an LHD (or LHA), an LPD, and an LSD. In addition, a cruiser and a number of destroyers and support ships fill out the ESG. The Marines embarked on the ships, 2,000 to 3,000 of them, make up a Marine Expeditionary Unit (MEU).

An American ESG is, obviously, a very powerful force projection unit on its own, particularly if accompanied by a nuclear attack sub. In combat zones, a Carrier Strike Group will usually be somewhere in the neighborhood as well.

UPDATE: Incidentally, though this is a post about Navy Amphibious Ships, it’s worth showing the Expeditionary Strike Group’s primary force projector:

U.S. Marines from the 11th Marine Expeditionary Unit take their positions during small-arms qualification on the flight deck of USS Peleliu (LHA 5) April 8, 2006. Peleliu, a member of Expeditionary Strike Group Three, is under way in the Indian Ocean in support of the war on terror. DoD photo by Photographer’s Mate 2nd Class Kerryl Cacho, U.S. Navy. (Released) Date Shot: 8 Apr 2006

Comments

  1. The confusion comes not solely from the nomenclature, which looks and sounds very much alike, but that they all do basically the same thing. The difference is really one of scale. But if that’s the primary difference, that this class can put more Marines ashore than that class, I’m foggy on why they would operate 4-5-6(?) distinct classes when it seems you only need one: the LHDs, with maximum infantry complement and air support.

  2. Marines – just be glad the flat-bottomed LST’s (Landing Ship, Tank) are gone. I spent some time on one – can’t remember the ship name – too busy puking. I think they were designed specifically to make Marines vomit. If so, the design was a smashing success.

  3. LHD – Landing, Helicopter, Deck That should be Dock. As in the large floodable well that was expanded compaired to the LHAs. GL: LSDs and LPDs are the same external, the LSDs are focused on cargo and LPDs on personnel. LPDs also carry the medical and staff commponents for when they split the ESG (LHA/LHD one direction and LSD with LPD elsewhere). That split ESG allows for detachments that would not be available if it was all ‘big decks’. LSD/LPD are also capable of getting into areas the LHA/LHDs are too big and have too deep of a draft for. Sometimes, bigger is not better, especially when it prevents you from going somewhere…

  4. DJ E, Yeah, I figured there was a tactical argument for allowing multiple classes and a more flexible amphibious force. But from a dollars standpoint, I’m not sure it’s cost-effective. It seems a big Wasp can do the job of several smaller, similarly-equipped vessels. I mean, LCACs, helos, or the new AAVs will go anywhere they need to put Marines, nu? So as far as *needing* a smaller carrier vessel like an LSD to get into shallower waters, I dunno. It seems it would be cheaper to operate 4 or 5 Wasps, say, than 12 Whidbey Islands.

  5. – LHA carries 1 LCAC; LHD 3; LPD 1; LSD 2. – Personnel carried per LCAC: 100 max (no cargo); or 4 LAVs; or 1 M1A1. – Most of the cargo for load or offload is still carried by LCU/LCVP. LVTP7s do only 5 knots in water. (AAAV is not fielded and does not add

  6. DJ E: ‘Think of the LPD/LSDs as the inshore combatants and the LHA/LHDs as the offshore carrier.’ Now that’s the little tidbit I was looking for that I could file away for future reference. Thanks MO and DJ Elliot. Murdoc Online: where knowledge happens.