LPD vs LSD

[HurricaneDitka]

I'm trying to understand the Marine's ARG composition. I've read that an ARG typically consists of one "big-deck" amphib and two "small-deck" amphibs, an LPD and an LSD. Why do we have both LPD's and LSD's? Are the LSD's just legacy equipment that will eventually be replaced with more San Antonio-class LPD's, or do LSD's offer some unique capability that we value and want to see continue in service? What are the different roles or capabilities of LPD's vs LSD's

 

[RobWilliams]

Amphibs like the San Antonio move large numbers of their troops as well as some associated vehicles of a MEU like AAV's to get them to the beach, LSDs like the Whidbey Island LSDs have a mahoosive dock and a huge capacity for carrying the heavier vehicles of the MEU including tanks, artillery etc

San Antonio can carry 2 LCAC or 1 LCU in their dock + 14 AAVs, an LPD can hold 5 LCAC's. That many large transports is really good for shifting heavier equipment ashore. LPD's don't carry helicopters because they don't move troops or lighter equipment through the air, that's the job of LPDs and LHDs.

Two pieces of the puzzle that makes up an ARG but both play an important part. Trying to build a ship big enough to do both roles would be horrendously expensive and the San Antonios haven't had the best ride through the press themselves.

 

[HurricaneDitka]

Thanks RobWilliams!

So, basically ...
LSD = fewer troops, more heavy vehicles and equipment, no helo hangar
LPD = more troops, fewer heavy vehicles and equipment, have helo hangar
(and for kicks)
LHA = even more troops, no heavy vehicles or equipment, more helos (and jets)

right?

 

[RobWilliams]

Pretty much yes, but that'll change when the 3rd America class LHA comes out with a dock making it an LHD.

Another way to think about it would be that it's the role of the LHD*/LHA/LPD to secure the beachhead then the LSD brings the majority of the rest of the equipment onto the beach.

*LHD has vehicle carrying capacity too including tanks, AAVs, artillery and the like.

If this PDF i'm looking at is accurate (I can't find a date and some of the vehicles have been upgraded since), then the ground element of an MEU consists of approximately

• 4 M1 Abrams tanks + M88 recovery vehicle
• 15 AAVs
• 8 - 17 M1161 Growlers
• 31 MTVs (7T trucks)
• 7 - 17 LAV-25s (+ 1 EW LAV)
• 105 HMMMWVs
• Unknown number of towed artillery guns
• Load of logisitics vehicles, trucks, bulldozers and the like

That's a lot of vehicles to move, so a prime vehicle mover with a dock like an LSD is ideal. In the UK LSDs are built cheaper and manned by members of the Royal Fleet Auxiliary so they provide cheaper sealift than our LPDs.

 

[John Fedup]

Amphibs like the San Antonio move large numbers of their troops as well as some associated vehicles of a MEU like AAV's to get them to the beach, LSDs like the Whidbey Island LSDs have a mahoosive dock and a huge capacity for carrying the heavier vehicles of the MEU including tanks, artillery etc

San Antonio can carry 2 LCAC or 1 LCU in their dock + 14 AAVs, an LPD can hold 5 LCAC's. That many large transports is really good for shifting heavier equipment ashore. LPD's don't carry helicopters because they don't move troops or lighter equipment through the air, that's the job of LPDs and LHDs.

Two pieces of the puzzle that makes up an ARG but both play an important part. Trying to build a ship big enough to do both roles would be horrendously expensive and the San Antonios haven't had the best ride through the press themselves.

I have not seen any recent negative press on the San Antonio class. It is my belief they are over the hump, yes?

 

[RobWilliams]

Yeah, but my point wasn't made in reference to recently just in general through the development of the class. Give a ship enough bad press in development and you can end up killing it if the political will isn't there to fully back it, so imagine taking up an LPD-17 with LSD capabilities built into it in one hull.

Wouldn't be pretty.

 

[colay]

I have not seen any recent negative press on the San Antonio class. It is my belief they are over the hump, yes?

It would appear so though it took some time to remedy the many maladies that plagued it after commissioning. Not unexpected in a first-of-class ship. USS San Antonio did earn a Battle Effectiveness award a couple of years back.