Freighter Bum - The Engine Room

	The Engine Room (...continued)	page one - two

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One can never be too careful when traveling by ship on the high seas. Admiral Judd makes a spot check of some of the valves feeding lube oil to the main engine.

Main Engine:

The main engine supplies power only to the propeller shaft and not to generators or any other auxiliary devices. It was a turbocharged, 7 cylinder, two-stroke engine producing 13,614 horsepower at 127 RPM. The “two-stroke” thing might come as a surprise to some people, who associate this type of engine with lawnmowers, dirt bikes and outboard motors. The engine had a bore of 0.5 meters and a stroke of 2 meters.

The engine is classified as a low-speed diesel. One of the characteristics of ships that use such an engine is that it there is no clutch or transmission between the engine and the propeller. The engine crankshaft is linked to the propeller without gearing. This has a couple of interesting consequences. First, there is no “neutral” mode in such a ship. If the main engine is running, then the propeller is turning and thrust is being applied (the propeller is fixed pitch). Second, in order for the ship to “back up” the engine must be stopped, and restarted in reverse.

The engine is designed to run on a very inexpensive, low-grade fuel known as “bunker 380”. In simple terms, this fuel is the residue left over from the oil refining process after all the more valuable distillates have been removed. It is very viscous or “thick”. At room temperature, bunker 380 is said to have a consistency similar to molasses, though I didn’t actually have the chance to see it in this form, myself. The fuel must be heated in order to reduce its viscosity enough to be pumped from the fuel tanks, and heated even further before it is thin enough for the engine to use it. The fuel must pass through a fuel filtering system roughly similar in appearance to that of a large swimming pool.

The engine is started using highly compressed air, which is injected sequentially into the cylinders. If the engine is undergoing a lot of starting and stopping when the ship is maneuvering, it is possible that the compressed air supply can be depleted and the engine can no longer be started until the compressed air supply can be recharged by the auxiliary engines.

Main Engine Efficiency:

(Your Mileage May Vary)

Based on information I obtained from the captain, as well as some density, cost and metric conversion information I found on the web, I calculated the following efficiency results:

Based on the following inputs:

Fuel Used:	40 metric tons /day
Ship Speed:	18 kts

The calculated mileage is:

Miles per Gal:	0.0467 mpg
Feet per Gal:	246 ft/gal
Gal per Mile:	21.4 gal/mile

The "bunker 380" fuel used by the main engine was selling for $133.50 per metric ton on the day I checked prices. This is about $0.50 per gallon. The main engine fuel cost comes out to about $5440 per day.

The auxiliary engines together typically use about 2.5 metric tons of the more expensive MDO fuel each day. (This is about twice as expensive as "bunker 380".) The daily fuel cost for operating the auxiliary engines comes out to about $670 per day.

Auxiliary Engines:

There are 4 auxiliary engines used for electric power generation. These “smaller” engines have ratings of 1394 HP, 1046 HP (2 units), and 777 HP, and run on MDO (Marine Diesel Oil), which very similar to conventional diesel fuel. The total electric power generating capability with all systems running is about 3 megawatts. Based on some information I was able to find on the web, this is the average electric power consumption of 2750 U.S. homes. At any one time, about half of the auxiliary engines may be running. The auxiliary engines use an average of 2.5 metric tons of fuel, total, per day.

Control Room:

The control room is a relatively quiet air-conditioned room located off the engine room, where most of the computers and other monitor and control electronics are located. The computers used are standard PCs. (Hewlett-Packard Vectra desktop PCs were used on the Katrin S.)

Engineering Department:

Seven of the 18 officers and crew aboard the Katrin S. were members of the engineering department. While at sea, this is typically an 8-to-5 job. Most of the work they perform is maintenance and cleaning of the large amount of equipment present in the engine room. The engineering officers review spreadsheet data that summarizes long-term trends in various parameters of the highly instrumented engine as a function of time. This can be used to provide clues to impending problems. Engine room operation is highly automated, so the actual running of the engines does not require hands-on supervision. One member of the engineering department is always “on-call” during off hours, however, to respond to various automatic monitoring system “alarms” that occur from time to time.

Once in port, the engine room crew typically works very long hours, since this is the only time in which major maintenance on the main engine and engine room equipment can be performed. As a result, the engine department doesn’t get much shore time.

Continue to the next section of Freighter Bum: Freight Operations.

The Engine Room, page one - two


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