Down in the Engine Room

The ship’s machinery was the domain of the Chief Engineer's department, but curious visitors were tolerated. Michelson’s engine room was hot. Very hot. Huge fans forced air down from the weather deck above, but it was still hot and very noisy as well. I could recognize the two boilers, but didn’t know what all the other stuff was supposed to do. There were pipes going in every direction, mostly clad with insulation. Rotating shafts and belts turned unknown things, probably unseen generators and pumps. Turbines, reduction gears, condensers, compressors, evaporators, valves and fuel pumps were a mechanical mystery. Asbestos was everywhere (!) but wasn't then regarded as being hazardous.

I've done some research as to how the engine room functioned. Steam power was quite complicated, labor intensive and kind of dangerous. Here is an overview of what happened in Michelson's mechanical spaces.

A cutaway view of a Victory Ship's engine room from a 1944-45 publication. Click for larger image.

Victory ships had two side-by-side single-pass boilers manufactured by Babcock & Wilcox, Foster-Wheeler or Combustion Engineering. At an operating pressure of 465 psi, the boilers could produce 27,500 pounds of steam per hour at 750 degrees F, with a furnace volume of 450 cubic feet. Together, they were 39-feet, 6-inches athwartship by 11-feet, 8-inches fore and aft, and 21-feet, 3-inches overall height to the top of the economizers. Fitted with superheaters, each boiler was fired with water-cooled side walls and refractory brick in the front and rear walls and floors.

Steamship fuel (#6 oil, a/k/a "bunker C") is the gooey stuff left over after gasoline, diesel, jet fuel and such are distilled out of the crude oil in the refinery. It is so viscous that it needs to be heated to around 180º F to be pumped to the burners. Thus, for a cold start, shore power or electricity from the standby generator was needed for the the heaters and pumps. Alternately, the boilers could be started with hand pumped diesel fuel.  

Periodically, accumulated soot in the boilers needed to be cleaned out. This is called "blowing the tubes". Coming out of the stack, this disgusting stuff got all over the deck, depending on wind direction.

Superheated high pressure steam drove the high and low pressure impulse-reaction type turbines rated at 6000 rpm, and the cross-compound double reduction gears which turned the 160 foot long, 16 inch diameter steel propeller shaft. Michelson's 18 foot diameter manganese bronze, four blade, right hand screw turned at about 100 rpm maximum for a speed of about 17 knots. Most Victory Ships had turbines and reduction gears furnished by Westinghouse, others had General Electric or Allis-Chalmers turbines. Falk reduction gears were found on some of the Victory Ships.

Besides propelling the ship, steam powered most everything.
  • The main nominally 450 pound (psi) steam system powered the propulsion turbines, entering the high pressure (HP) turbine (starboard side) first, then through the port turbine (low pressure). The ship's propeller was reversed by directing steam to the astern blades on the HP turbine using the throttle wheels in the engine room. 450 pound steam also drove the two ship's service electrical generators. 
  • Back up 450 pound steam was available from the boilers through an auxiliary distribution system. 
  • 450 pound steam went through a reducing valve to the 240 pound system which turned the two forced draft blowers that acted like turbochargers for the boilers.
  • 240 pound steam drove bilge, fire, fuel and general service pumps. Connections were available for to external shore steam at 240 pound pressure when in port. 
  • Steam, further reduced in pressure to 160 pounds, turned the engine room ventilating and exhaust fans and supplied the evaporators. 
  • The ship's whistle had its own supply of 110 pound steam. A 100 pound supply went to the ship's laundry. 
  • After another reduction in pressure, 35 pound steam went off in all directions to water heaters, the galley and living quarters heating radiators.  
  • The D.C. Heater (feedwater heater) was supplied with 10 psi steam reduced from the 240 pound system.

Allis-Chalmers low pressure turbine and Falk reduction gears. Photo on SS Lane Victory, a 6,000 hp VC2-S-AP2 vessel.

Some of the VC2-S-AP3 Victory Ships (like SS Joliet Victory / USNS Michelson) were built with General Electric turbines and reduction gears delivering 8,500 hp.

Michelson, as well as Bowditch and Dutton, were the more powerful and slightly faster 8,500 hp VC2-S-AP3 Victory Ships. The VC2-S-AP2 models had the same hull but 6,000 hp capacity engines. The difference in performance was a function of the turbine and reduction gear combination. There were several suppliers of turbines and gear boxes. Available details of Victory Ship mechanical systems are sketchy and sometimes contradictory. 

My primary source of information was USS Liberty Mechanical Systems Drawings (1964-65) by Lt. George Golden and Jim Williamson EM3, which can be found online. USS Liberty, originally SS Simmons Victory (another VC2-S-AP3), was the US Navy intelligence gathering vessel that was nearly sunk, with great loss of life, by Israeli forces in 1967. While the ship was heavily modified, the original 1945 mechanical systems were largely still in place and are well documented in the drawings by Golden and Williamson.


Here is how one type of reduction gears worked. The axis of the large gear was connected (on the right) to the ship's drive shaft through the "shaft alley"tunnel back to the propeller (screw) at the stern. In this diagram the high and low pressure turbines are transposed: on Victory Ships the high pressure turbine was on the starboard side, the low pressure toward the port side of the engine room. There were multpl;e vendors for the turbine/gear combination. 

The shaft tunnel (shaft alley) on museum ship SS Lane Victory, one of the three remaining Victory hulls. Michelson's drive shaft was the original polished steel, not painted white. It was so shiny that you could hardly tell it was turning! This was an awesome sight indeed; a 160 foot driveshaft delivering 8,500 hp to the ship's huge propeller.

The engine room diagram does not identify the location of the fuel pumps and valves. These are probably on the upper level, port side. The settling tanks and fuel heaters were just forward of the two boilers. I believe that the cylindrical devices outboard of each boiler were the blowers that supplied draft to the boilers. These were steam driven and very noisy. 

Victory ship engine rooms originally had two steam turbine driven 300 kw three wire 120/240 volt DC generators (turbo generators). As built in 1944 and 1945, the ships were wired entirely for DC (direct current) as was common at the time. Provision for 120/240 volt DC shore power was at the connection box on the forward side of the superstructure, main deck, starboard side.

Some devices that required AC (alternating current) had their own power conversion, for example the gyro compass, located on the 03 deck across from the radio room. It used its own dynamotor (rotary DC-to-AC) converter. 

At the time of its conversion to a survey ship the original two 300 kw turbo generators were replaced with two 900 kw 600 volt DC units. These also supplied 120 and 240 volt DC power. A third turbo generator (or possibly a motor-alternator set) was added to supply 120/240 volt AC for the ship's domestic needs.

Additionally, three 600 volt DC-to-AC motor-generator sets, transformers and a AC power distribution board were installed in the electrician's shop on the second deck, port side, in the Navy OCDET spaces. Typically two of the three M/G sets ran continuously furnishing 120/240 volt AC power to electronic equipment in the technical spaces.

Missing in the cutaway drawing (above at top) are the compressors and coolant pumps for the 1944 original refrigeration and freezer.  This equipment was probably on the upper engine room level on the starboard side.  Similar units supporting the air conditioning added in 1958 were there as well. Fresh water was supplied by the evaporators, also in that area.