Far out on the lake, a tug-barge can look like any of the other monster freight vessels that loll along the horizon. But as it closes in, finer points emerge. Two distinct names - one painted on the barge, one on back of the tug - and the sight of a tug tucked into the backside of the barge.

"Most of the tug-barge combinations are converted from old ships," said 21-year Great Lakes pilot John Swartout, who guides foreign-flagged vessels to ports inland from the Atlantic Ocean.

The slow rise of the tug-barge on the Great Lakes really began with the story of the thousand-foot lake freighter.

Acclaimed Great Lakes author and historian Frederick Stonehouse tells of an old captain talking about lake freighters.

"He told me the ships were eternal as long as you're willing to replace the parts," Stonehouse recalled before offering up his thoughts on the topic. "But it would get to a point that the maintenance wasn't feasible. The vessels themselves, even though you replace the keel, put in new shell plates, work on the longitudinal infrastructure, it still is an old ship."

The last thousand-foot freighter, Paul R. Tregurtha, was built in 1981, following a boom in the 1970s. Those freighters changed shipping on the lakes, multiplying the amount of cargo that could be toted by the previous generation's ships. A lot of old and antiquated ships were replaced without sacrificing tonnage.

"We went from carrying 12,000 tons to 70,000 tons," said Interlake Steamship Company President Mark W. Barker from his office southwest of Cleveland. "It was the equivalent of six ships in 1970."

But that was more than 35 years ago. It's been so long, there might be only one American shipyard on the Great Lakes, in Sturgeon Bay, Wis., that can even think about having the capacity to build a brand new lake freighter, sources for this story said. So it is that people in and around the industry both share and hear the whispers: "They're not building ships anymore on the Great Lakes ... the industry doesn't modernize."

"People like to say the industry doesn't modernize, but that's a naive comment," Barker said. "You have to look at what makes sense for the industry - how do we keep moving raw materials inexpensively?"

Advent of the tug-barge

No longer turning out freighters, domestic fleet owners have turned to another configuration of cargo mover: tug-barges. The tug-barges first appeared on the lakes in the 1990s and remain the newest domestic arrivals to fleet rosters.

You can imagine a tug-barge as chopping off the stern end of a ship, notching it and plugging in a tug. The tug consolidates living space for a smaller crew, while also providing in most cases a modern engine room and power plant.

It's popular in the Gulf of Mexico and along the North American coasts, where tug-barges are prominent and skillfully made at coastal shipyards. Some tug barges run from California all way to Alaska in heavy weather, said Barker, whose Interlake owns and operates Tregurtha. It also operates a tug-barge, the Dorothy Ann-Pathfinder.

"I'll put my engine room up against any in the world," he said of a the company's 600-plus-foot, 26,000-ton tug-barge. "It looks newer and more modern. But we do get some incremental deficiencies," explaining those as the result of the way sailing with a notch creates more resistance from the water.

"The tug doesn't fit perfectly into the notch," Barker said.

Any Great Lakes ship owner would love to build new ships, Barker said, but it just doesn't make economic sense.

It also doesn't mean the domestic lake freight industry isn't keeping up. When it came time to modernize five ships in its fleet, Interlake weighed creating more tug-barges, but instead chose to invest in repowering the ships with diesel engines. It finished in 2016.

"We still have areas of our hulls with their original thickness of the steel," Barker said about the lastingness of his fleet. "So we went with reuse and recycle, and gave the assets a new life. We recycled - but people still like to say the industry doesn't modernize."

The repowering offered slightly better speed and horsepower than the most modern tug-barges. Those efficiencies offset the fact that tug-barges can legally operate with smaller crews than lake freighters.

Able to clip at up to 21 mph, a tug-barge has other advantages. Barker compared it to a tractor-trailer on the roadway. The barge is functionally "dumb," he said, while the tug consolidates all of the electricity and other life-sustaining capabilities. Additionally, some of the tugs can even disengage from the barge and break ice when needed.

Compared to Canada

Fednav is a Canadian company that operates roughly 100 ships, two-thirds of which make passage in the Great Lakes. Between 2015-16, the company added 10 brand new, state-of-the-art ships to its roster.

"We really specialize in lake business," said Fednav spokesman Marc Gagnon, based in Montreal. "But comparing us to the ships built in the U.S. is really apples and oranges."

The bulk of Fednav ships operate internationally by importing manufacturing equipment and other break-bulk cargoes into the North American interior, Gagnon explained, while typically sailing out of the Great Lakes with grain bound for ports overseas.

The corrosive waters of the oceans make what Fednav does different than the work of, say, the domestic ore carriers. Fednav has to watch its hulls corrode across 20 years of service life. In those cases, there is no eternal life or chopping a ship to be retrofit into a tug-barge.

The company's recently added Japanese-built ships feature the latest in ballast water technology and greenhouse efficiency. The new ships came at a cost of roughly $25 million per vessel, Gagnon said. What makes it easier for Fednav to turn to new ships is the fact it isn't bound to the stricter regulations of the U.S. carriers.

The Jones Act requires cargo moved between U.S. ports be carried in vessels which are U.S.-owned, -built and domestically crewed. It's a hurdle that inflates ship-making costs, and forces domestic owners to think more creatively.

As the economy changed in recent decades, and some of the Great Lakes tonnage disappeared, the tug-barge became an inexpensive and go-to option - for the simplest reason of all.

"They're good boats," Barker said.