A 1947 US Motors Diesel Generator on a Historic Ship

Diesel generators have many uses aboard a ship. Usually they have a fairly central role, with devices of many types being powered by the electricity produced. When you go back in time to when steam ruled, diesel generators were less central and sometimes used only for a single purpose. Case in point; the SS Col. James M. Schoonmaker, a Great Lakes ore boat that was built in 1911 and operational through 1980.

Ok, right now some of you ex-mariners are screaming, “A 617 foot long vessel is not a boat, you dufus!” First, the guy writing this is a former U.S. Army mariner, so he knows the difference between a ship and a boat, but he had to learn that mariners on the Great Lakes use different terminology… and now you do. One; vessels on the lakes are called boats, regardless of size. Two; they measure speed and distance   on the lakes in statute miles, not nautical miles. Go figure.

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Deep in the engine room of the SS James M. Schoonmaker lives this unobtrusive diesel generator. It’s a US Motors model D50D 50KW set powered by a 529 cubic inch Hercules DXRC indirect-injected diesel. The generator makes 50 kilowatts of DC power (400 amps at 125 volts) and powers the 6.5-ton deck hatch crane, as well as a DC-to-AC motor generator. The radiator may seem strange to you, given that most marine installations involve using raw water cooling (with or without heat exchangers). This generator was not designed to run for long periods and the radiator setup reduced installation costs. Given the engine room is well ventilated because of the nearby boilers and steam turbines, it’s not likely running it for an extended period would be much of an issue anyway.

The Schoonmaker was steam powered and electrified from the start using steam generators, which can work only when steam is up. At some point, internal combustion engines entered the scene for Schoonmaker but the history of that is not clear. She got a big 150 KW unit in 1952, when the main propulsion was updated from the original reciprocating engine to turbines. The generator was mainly used to power the ship while the boilers were being fired up, or in an emergency. The museum historians only know about one internal combustion generator she had before 1952, the one featured here.

Over many years of service, a ship will undergo modifications to improve it’s performance and utility. Such a thing happened in 1947-48 during the winter layup, when the main cargo hatches were modified from 35 small telescoping hatches to 18 larger hatches with removable covers. This allowed the ship to be loaded faster and with less crew than the telescoping hatches. Part of that conversion included a 6.5-ton Northern Engineering Works hatch crane powered by a DC electric motor. As part of the installation, a diesel generator was installed and it may have been Schoonmaker’s first diesel engine. It was a generator set from United States Motors Corporation powered by a Hercules diesel.

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This is a motor generator, with a DC motor driving an AC generator. It’s an inefficient way to convert DC to AC, losing about 25% in the process.  Our best guess is the US Motors genny operated this to supply a small amount of shipboard power. We’d like to go back and trace out cables to prove that.

It’s known the generator’s main task was to run the deck crane. It’s difficult to understand the logic for that, but at the time it was installed, it’s likely the ship didn’t have an independent generator to run it without the boilers being lit and the costs of keeping boilers stoked while the ship was being loaded and unloaded was prohibitive. Plus, the ship was AC and the crane motor was DC. The generator was just big enough to also run some limited shipboard circuits, perhaps just for lights. Saying it actually did involves a certain amount of speculation, but museum records do not show any other diesel generators prior to 1948 so it’s logical to assume the generator did more than run the crane until the bigger generator was installed in 1952. The 1947 set remained in service until the boat retired in December of 1980.

US Motors

The 1947 generator came from a company that was once a power player in the field of generator sets, United States Motors Corporation, also known as US Motors and sometimes US Diesel. US Motors had it’s roots in the Union Iron Works, founded by Herman C. Doman (1858-1938) and Herman Manuel in 1886, operating out of Oshkosh, Wisconsin. They mainly manufactured steam engines and parts. Doman bought Manuel out in 1891 and renamed the firm H.C. Doman Company. Doman introduced gasoline engines in about 1902 and developed a very well-regarded line of gas marine engines. Doman retired in 1910 and sold out to P. Sawyer & Son, a company run by Edgar P. Sawyer of the Oshkosh Sawyers, a family that became millionaires in the Wisconsin timber industry but diversified into other businesses in the area.

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As far as we could learn, the Sawyers let the company run as H.C. Doman until the latter part of 1920, when it was sold to Universal Products Company of Sandusky, Ohio. Universal manufactured generator sets and related products. After buying Doman, they moved their operation to Oshkosh right away and expanded their manufacturing footprint by combining the two businesses. Universal Products should not be confused with Universal Motor Company, also of Oshkosh, and nearly a legend in marine propulsion. In addition to their generating plants, Universal Products continued to manufacture the Doman line of “Falcon” marine engines. In 1927, they changed their name to United States Motors Corporation (commonly known as US Motors), continuing and expanding in the power generating field. They mostly purchased outside engines and generators heads, putting them together into sets.

US Motors was a big player in power generation from the ‘20s into at least the ‘70s, and probably the ‘80s, but little other than entries in catalogs and adverting remains to document their history. We could not find the date they closed up shop, but in the ‘60s they were still hitting the standby power market hard with units from 500 watts to 750 kilowatts.

Hercules Motor Corporation

Founded in 1915 as Hercules Motor Manufacturing Company, the firm was based in Canton, Ohio. Hercules established a strong reputation and grew through the ‘20s and ‘30s, pioneering diesel engines in the early ‘30s with cutting-edge swirl-chamber indirect injection. When World War II came along, they built more than 750,000 engines of many types, many of them powering legendary military vehicles such as the 4-ton Diamond-T 6×6, 45-ton M-20 tank transporter, M-8 and M-20 armored cars and the full line of Studebaker 2-1/2-ton 6×6 trucks. They also had a big wartime presence in marine applications, as well as stationary power.

After the war, Hercules struggled in the civilian market against a bevy of competition but thrived in military contracts. They built the engines for the M-151 MUTT Jeeps and the multifuel diesels for the 2-1/2 and 5-ton 6x6s. Eventually, they devoted most of their resources to that market and that narrow focus became part of their undoing when contracts dried up in the ‘80s. They were bought several times and merged with other companies as separate divisions. With each acquisition, their financial situation became more precarious and the Canton plant finally closed in 1999. Hercules Manufacturing took over most of their assets, blueprints, tooling and now supplies parts for many Hercules engines.

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Deep in the engine room of the SS James M. Schoonmaker lives this unobtrusive diesel generator. It’s a US Motors model D50D 50KW set powered by a 529 cubic inch Hercules DXRC indirect-injected diesel. The generator makes 50 kilowatts of DC power (400 amps at 125 volts) and powers the 6.5-ton deck hatch crane, as well as a DC-to-AC motor generator. The radiator may seem strange to you, given that most marine installations involve using raw water cooling (with or without heat exchangers). This generator was not designed to run for long periods and the radiator setup reduced installation costs. Given the engine room is well ventilated because of the nearby boilers and steam turbines, it’s not likely running it for an extended period would be much of an issue anyway.

SS Col. James M. Schoonmaker

Still Floating at 108 Years Old

The fresh water of the Great Lakes is kind to watercraft of all types and sizes but for a commercial vessel to remain in active service for more than 70 years requires a well-found craft. Schoonmaker was launched July 1, 1911 at the Great Lakes Engineering Works at Ecorse, Michigan. For three years, she was the largest ship operating on the Great Lakes. At 617 feet long and with a beam of 64 feat, she could carry 12,200 tons of bulk cargo as built… typically iron ore or coal, and sometimes grain. During the hard times of the great Depression of the early 1930s, she even carried a deck full of automobiles.

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On this foggy morning, the 617 foot Schoonmaker almost disappears into the mist. At the time she was built, she was the Queen of the Lakes, in both size and appointments. We have a couple of other engines to showcase from her and we’ll show you more of the ship.

Schoonmaker was the flagship of the Shenango Furnace Company and was more ornate and well appointed than most of the ore boats. She had five luxury guest cabins, a passenger lounge and carried many notables in her long career, including Andrew Carnegie. Shenango not only made steel but had its own fleet of five ships to move ore. Shenango sold Schoonmaker in 1969 to Interlake Steel Corporation who sold her again in 1971 to Cleveland Cliffs Iron Company, who renamed her Willis B. Boyer. She operated under that name until retired in December of 1980. She still had at least 10 more good years before a more stringent regulatory process would have phased her out, but major downturns in manufacturing and higher costs of operation made her impractical to operate. Boyer was laid up until 1987, when the city of Toledo saved her from the scrapper and purchased her as a museum ship. She was given a cosmetic makeover to her original Shenango colors in 2011. On the 100th anniversary of her launch, she was rechristened to her original name by a descendant of her namesake Colonel James M. Schoonmaker, a Congressional Medal of Honor winner in the Civil War. She was moved to her present site in 2012 and the Museum of the Great lakes opened in 2014, with Schoonmaker as a centerpiece.

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courtesy The Museum of the Great Lakes

As built, Schoonmaker was powered by a four-cylinder, quadruple-expansion reciprocating steam engine that made 2,500 horsepower and used a pair of coal-fired Scotch boilers. That doesn’t seem like a lot of power for a ship this size, and it wasn’t, but it was more than most lake boats of the period. Lake boats were typically underpowered, with owners valuing economy over speed and power. Schoonmaker could crank out a maximum of about 14 miles per hour with a load. In 1952, Schoonmaker was repowered with a 5,000 horsepower Westinghouse steam turbine operated by oil-fired D-Type boilers from Combustion Engineering. That didn’t offer much more speed but the new plant was more economical, maneuverable, reliable and safe. It also allowed her to carry more cargo and she set a new cargo tonnage record of 15,868 tons in 1953.

The Museum of the Great Lakes on the Maumee River in Toledo houses a huge collection of maritime artifacts and interactive exhibits. The Schoonmaker and tug Ohio are just two of those and you can walk their decks on self-guided tours. The Museum gave us special access to the engine rooms of both vessels and you can look forward to more marine diesel content in future columns.

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