Liberty Ships

One of Roamy’s very first posts here concerned the WWII emergency shipbuilding program known as Liberty Ships.

As it happens, I recently acquired a book on Liberty Ships.

The haste with which they were built, and the relatively new technology of welded hulls, lead to some issues with brittle metal, and hull failures, especially in cold water.

The massive Liberty Ship program was designed to quickly build as many general purpose (break bulk) cargo ships as possible. The Liberty Ships were simple, but not crude.

http://www.byteland.org/taltales/liberty_ship.jpg

The primary bottlenecks in shipbuilding were these:

First, the program could not be allowed to compete with existing merchant and warship building. To avoid this, entirely new yards and slipways were built (at government expense). In fact, many of the companies that operated these yards had no history of shipbuilding at all. Indeed, these neophyte firms often brought innovations to shipbuilding that left older firms aghast, but were eventually adopted by traditional firms, and are still in use today.

Second, the real bottleneck in production was propulsion. By 1940, the triple expansion steam engine was widely considered obsolete in American merchant marine service. But most production intense part of a steam turbine plant is the reduction gearing. There was a very real limit to how much gear cutting capacity America had or could be expected to achieve, and virtually all that was allocated to warship production. And since geared turbines were out, the old triple expansion steam engine was pressed into service for the Liberties. That actually meant that a school for teaching how to maintain the older technology had to be opened. The relative simplicity of the TESE meant that foundries that normally had no maritime connection could also be used to build engines.  The boilers were also relatively simple (though not crude) and could similarly be build without competing for the limited capacity of traditional boilermakers for warships.

———————————————————————

Now, you know that massive losses to merchant shipping to U-Boats in the Atlantic spurred the Liberty Ship program.

What surprised me was the relatively small numbers of Liberty Ships that were lost to U-Boat attacks.  I suspect it is because the worst losses of the Battle of the Atlantic took place before the Liberty Ship program really started placing large numbers of ships into service. That is, most were replacements for losses already incurred. There were appalling numbers of losses, but most were from mechanical casualties, and very often after 20 years of service.

————————————————————————–

One thing I found rather spartan about the ships was that the navigation suite consisted primarily of a magnetic compass. Combined with a sextant and charts, that was about it. The lack of a gyrocompass was surprising. Virtually none of the Liberty Ships was fitted with radar of any sort during the war.

USAV John U. D. Page

It’s not often I come across a type of ship in US service I’d never heard of before.

In the mid-1960s, the Roll-On/Roll-Off (RO/RO) type of transport vessel was first designed, the early example being USNS Comet. Trucks and tanks and other vehicles would simply be driven aboard a ship and parked. It was originally seen as a way of reducing the number of times a given cargo would have to be handled. Rather than unloading truckloads of cargo onto a ship and then unloading said cargoes off the ship into a truck at the destination, the reasoning was that loaded trucks could simply be shipped.

As a method of moving cargo, it was fairly inefficient The container carrying cargo ship would address that need in a far more efficient manner in just a few years.

But it was hardly a failure, as it turned out RO/RO was an excellent way of transporting the vehicles themselves to a theater of war.

If the RO/RO could berth in an established port, no problem. Simply lower the ramp to the quayside, and drive the vehicles off.

But many theaters, such as Vietnam, had only the most primitive port facilities, and often not even that. Another method of delivering the vehicles from ship to shore would be needed. The Army’s small LCM and LCU beaching craft would simply unable to unload vehicles fast enough.

Accordingly, the Army (the lead DoD agency for Over The Shore Logistics) developed the Beach Discharge Lighter.  Named the US Army Vessel John U.D. Page, the BDL was 338 feet long and displaced about 2000 tons. A flat, open vehicle deck supported a thin center island for the ships bridge and stack. A flat open area aft was designed to mate with the stern ramp of USNS Comet. A bow ramp was designed to discharge vehicles over a beach. Cyclodial propellers* gave the BDL excellent maneuverability, and the ability to turn within her own length.

The Page entered service in 1958, and self deployed across both the Atlantic and the Pacific. She spent much of the Vietnam war in those waters, facilitating the delivery of cargo both from RO/RO ships and conventional cargo ships to unimproved ports. The Page was the only vessel of the class built, and she served until 1985.

http://www.militaryimages.net/photopost/data/716/Vietnam_War21.jpg

—–

http://www.navsource.org/archives/10/17/10170703.jpg

—–

http://grambo.us/myers/3611dbdf.gif

In the picture above, you see the page alongside a US Navy LST, and they’re of comparable size. But understand that the BDL was not designed to carry vehicles and cargo on long oceanic voyages, nor was she intended to support an assault landing. She lacked the berthing and messing spaces that an LST provided for vehicle crews, and her open deck, while facilitating rapid loading and unloading, would leave vehicles vulnerable to sea and wind damage on the open ocean. Her open deck, and larger bow ramp, allow her to carry larger vehicles than the LST could, for instance, later main battle tanks such as the M60.

[youtube=http://www.youtube.com/watch?v=irDmmcuU_f4]

* Fairly common now on tugboats and ferries, the CD drive was first tested in the US on a modified LSM.