LST Development and Death

The LST was a WWII development intended to provide amphibious assault landing capability on a much larger scale than the individual, small landing craft.  In this role it was hugely successful.  So, given that the Navy has no LSTs anymore, what happened to its development that led to abandoning a combat proven, immensely valuable vessel?

Let’s briefly review the original WWII LST(v2).  As we know, it was purpose designed for larger scale beaching unloads.  As such, it was not normally part of the initial assault wave but was a key part of the follow on reinforcement and sustainment effort.  It was able to land a large quantity of troops and vehicles without requiring a port, artificial harbor, or other extraordinary effort.  With a bow door and ramp, vehicles were able to simply drive straight off the vehicle deck, across the ramp, onto the beach, and into the fight.  

WWII LST

The cargo capacity was 2,100 tons and approximately 200 soldiers. Its heart was a tank deck which was 230 ft long, 30 ft wide, and 12 ft tall. (1)  Well over a thousand LSTs were built during the war and hundreds served around the world for many decades after the war.

The LST was a nice balance of rapid construction (two months build time), low cost, low risk versus payload, and efficient delivery directly to the beach.

Post-war, in the late 1950’s, the US Navy built seven new LSTs designated the De Soto County class.  It was 445 ft long versus the WWII LST of 327 ft.  The main refinement seems to have been improved habitability for crew and embarked troops.  This class marked the beginning of the end for the LST in US Navy service.  It was a significantly larger ship that offered no new or improved combat capability and marked an unwise trend toward deployments over missions.

De Soto County Class LST

In 1969, the Navy finalized the ruination of the LST with the construction of the Newport class which was substantially larger, more complex in design and operation (a Mickey Mouse derrick/ramp, over-the-bow arrangement and bow thrusters), and incorporated a stern gate to launch AAVs and mate LCUs.

Newport Class LST - Note Over-the-Bow Ramp

Here’s a comparison of the WWII LST and the Newport LST.

	LST	Newport
Length, ft	327	522
Width, ft	50	70
Crew	120	220
Transport, troops	140	400

Newport Class LST - Note Flight Deck

We see, in the LST design history, today’s trend toward deployment ‘cruise’ ships meant to house troops for extended periods instead of just for the duration of an assault. 

The trend towards deployments and permanent troop housing led to the explosive size growth of the type.  Compare the original LST at 327 ft long with the Newport class at 522 ft – with no concomitant increase in combat capability, just a larger size which made the ship a larger target and greater risk, contrary to the combat dictate of spreading the risk.  Yes, some small growth could reasonably have been expected given the increase in tank and vehicle size but much of the increase went to habitability rather than capacity.

Other than a core of LSTs maintained for training and tactics development, LSTs should never have been turned into ‘cruise’ ships.  They should have been tied up pierside and left until needed.  A simple rotational schedule for training exercises would suffice to keep the ships mechanically maintained and operable and core of crews trained.

Because the LST became a deployment asset rather than a mission asset, it had to perform more functions.  The LST became more of an amphibious ‘base’ ship than a single function landing vessel.  This is seen in the provision of a stern gate in the Newport class to allow AAV launches and mating with LCUs and the incorporation of a flight deck.  This eventually led to the amphibious fleet of today which epitomizes all the weaknesses we’ve discussed: concentration of risk, unaffordable cost, deployments over missions, and sub-optimal capability for the combined roles of aviation and transport.

By abandoning the single function, combat-focused design in favor of a deployment ‘cruise’ ship meant to house troops for extended periods, the Navy made the LST unaffordable relative to its other budget desires  …  …  …  and the LST vanished from the fleet.

There’s a larger issue, here, and that is that we’re peacetime designing warships out of existence by giving them non-combat features until they become unaffordable.  Once war ended and the sharp, laser-focus on combat capabilities vanished our ship designs began wandering into peacetime requirements of comfort and endurance rather than combat.  We now have a fleet of compromised designs intended for peacetime use rather than war.

We need to bring the LST back but only in its original form:  cheap, quick to build, mission oriented, and without peacetime frills.

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(1)https://www.army.mil/article/10067/lst_in_wwii