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:
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