Monday, August 8, 2016

Lighting Off a Liberty Ship

The aft 5-inch 38 caliber gun of the Liberty ship SS John W. Brown, one of only two in America that have been restored to operational condition, is seen in the foreground of this panorama taken in downtown Norfolk during her recent visit, which also includes USS Wisconsin (BB-64).  Among museum ships, battleships are far more plentiful and enjoy a vastly higher profile, yet the Liberty Ships, which were much cheaper to build than battleships and disposed of for pennies on the dollar after the Second World War, had a greater role in the allied victory. (Photo by M.C. Farrington)

Having made the transatlantic crossing, Liberty ships gather in Cherbourg harbor, France in July 1944.  An LCT (Landing Craft, Tank) and a DUKW (the amphibious Army cargo truck popularly known as the "duck") can be seen in the foreground. (National Museum of the U.S. Navy Photograph Curator via Flickr)
It's the time of year when our thoughts in the Tidewater turn to the heat.  That sultry haze that settles over Hampton Roads that one can see while stranded on either side of the Hampton Roads Bridge-Tunnel, or the shimmering mirages over the roads of Norfolk or Newport News.  But if nothing else, history gives us a sense of how fortunate we are today with our air conditioning and moisture-wicking fabrics.  Imagine standing watch, scanning the horizon endlessly from the gun tub of a Liberty ship under the blazing sun off the coast of North Africa or transiting the South Pacific below decks amid the soot, clatter and drone in an engineering space so hot that a few minutes of it could bring on heat exhaustion.  

During the Second World War, on multiple voyages that frequently took her to and from Hampton Roads, SS John W. Brown delivered tanks and ammunition to Russia and American Soldiers sojourned aboard her on their way to the invasions of North Africa, Southern France and Italy.  Some of the axis prisoners they took returned on the ship to the United States for internment. All the while, members of the U.S. Navy Armed Guard, many of whom underwent training at the Armed Guard School at Little Creek, Virginia, stood continual watches in the gun tubs distributed about her upper decks. During the landings in Southern France, they could claim the downing of an attacking German aircraft.  The end of the war did not end her wartime mission as the Brown continued transporting much needed coal and grain to Europe, and bringing back hundreds of Americans on her return journeys.
A portion of the James River Reserve Fleet, photographed in 1990 by Photographer's Mate 3rd Class Martin Norman. This was the end of the line for hundreds of Liberty ships that were either sold off to foreign governments, private shipping companies, or ship breakers.  Many were also used as targets during live-fire exercises. (U.S. Navy Photo via Wikimedia Commons)
From 1946 to 1982, she escaped the fates that befell most of the over 2,700 Liberty ships produced during the war, serving as a floating vocational high school in New York City. For several years afterward her station was with the James River Reserve Fleet off Ft. Eustis, one of the thousands of vessels belonging to the National Defense Reserve Fleet.  But before John W. Brown could be consigned to the torch, become a practice target or serve as a new artificial reef, rescue arrived in the form of an organization called Project Liberty Ship, dedicated to preserving the hybrid troop transport as a part of its mission to preserve the memory of the ships, the hundreds of thousands of merchant mariners, and the nearly 145,000 Sailors of the Armed Guard who served, fought, and sometimes died aboard them.
SS John W. Brown, shown in 2012 at her home port of Baltimore, Maryland, opposite Ft. McHenry. (MKelly/ Wikimedia Commons)
In 1983, President Ronald Reagan signed a bill authorizing the transfer of SS John W. Brown from the U.S. Government to Project Liberty Ship, and she was moved from the reserve fleet down to a Norfolk shipyard, where volunteers spent hundreds of hours restoring her to original condition, even reinstalling many of the same types of guns used by the armed guards. She now resides in Baltimore, where she was launched on Labor Day, September 7, 1942, from Fairfield Shipyard, a subsidiary of the Bethlehem Steel Corporation, approximately 41 days after her keel was laid. Additional outfitting took approximately another month before she was ready to serve. At the time, Liberty ships typically cost $1.7 million to produce. 

Typical layout of a multi-purpose Liberty ship.  (National Museum of the U.S. Navy Photograph Curator via Flickr)
Originally designed for transporting cargo only, SS John W. Brown was one of the many Liberty ships converted to transport passengers; American troops as well as enemy prisoners of war. Many of the converted passenger liners dedicated to the task of transporting personnel were simply too large to deliver troops to where they were needed as the allied tide swept the Axis powers back throughout North Africa and the Mediterranean, so the US Army’s Chief of Transportation made the call to convert many of the Liberty Ships to "Limited Capacity Troopships."  Approximately 40% of the allied troops that embarked from Hampton Roads during the war, 202,247 from June 1943 to May 1944 alone, were transported on the modified Liberty Ships.  John W. Brown alone is believed to have carried 10,000 military personnel from both sides during the war.

The cylinder head of SS John W. Brown covers a 76 inch-wide piston the largest in its triple-expansion engine. (Photo by M.C. Farrington

Her engineering section amidships is dominated by two gigantic boilers providing steam at 200 pounds per-square-inch that is used for the steering gear, the cargo winches, and even the ship’s whistle. But what the steam is mostly used for is its engine. Its cylinder head towers nearly 25 feet over the engineering space main deck, giving the visitor the feeling of being shut up under the hood of a gigantic delivery truck sitting at idle.
Hal Raper, a retired Navy dental officer and engineering volunteer for the Brown, explains the operation of the triple-expanding engine on the upper deck of the engineering space.  The cylinder head can be seen behind him to the left. (Photo by M.C. Farrington)
In a standard internal combustion engine, a fuel-air mixture is delivered to individual cylinders that are equal in size and that co-equally drive the crankshaft they are connected to through coordinated, electronically-timed explosions, which push the pistons inside the cylinders and the rods that connect them with the crankshaft downward. What remains of the fuel-air mixture after combustion is quickly removed via exhaust valves, whereupon more fuel and air is drawn into the cylinders by the pistons and the whole process starts again.  By comparison, the massive pistons within the condensing, triple-expansion engine aboard John Brown, typical of those aboard liberty ships, aren’t directly propelled by combustion at all.

In a direct-acting, condensing engine, steam heated by the boilers enters the first 24-inch cylinder at 200 psi and pushes a piston within it downward, allowing the rapidly expanding and cooling steam through a valve into a second 36-inch cylinder, pushing the second piston downward and allowing the steam through another valve into a third, 76-inch cylinder.  At 76 RPM, it can produce 2,500 shaft horsepower and propel the ship at around 11 knots. 

Robert Mullarky prepares to light SS John W. Brown's port boiler. (Photo by M.C. Farrington)

Although they were designed with the latest mass-production techniques in mind, Liberty ships were not designed with modern means of propulsion.  Robert Mullarky, a professional marine engineer from Baltimore acting as John W. Brown's chief engineer during the visit to Norfolk, explained that the design of the propulsion system was antiquated,  even by 1940s standards.  "The basic design goes back to the 1880s-1890s,"explained Mullarky.  In 1942, the U.S. Maritime Commission chose an 1879 design based on a British "powered scow," that became the mass-produced British Ocean class and the American Liberty ships.  The design had a proven track record on the Atlantic Ocean, and the cargo vessels could be made economically, using a wide range of production methods and shipyards. 

Mullarky said that ambient temperatures in the engineering spaces are kept tolerable while underway by giant forced draft fans on the engine room floor, which draw in air through the ventilators sticking out above the main deck like giant horns.  The air is vital for maintaining combustion within the boilers, which while underway are hot enough inside to melt steel.  The inrush of air also helps regulate the engine room's ambient temperature, but the seawater temperature outside the skin of the ship is also an important factor, which at the time of their visit was in the low 60s Fahrenheit.  Setting aside the constant threat of a torpedo attack, the lower water temperatures of a wartime run to the North Atlantic would make the experience for the engineers fairly tolerable.  Ambient water temperatures in the South Pacific during the war, however, were known to get into the upper 80s.  Under those circumstances, Mullarky said, the temperature within the engineering spaces could reach 120 degrees.  

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