I could almost hear my father’s jaw clattering on the floor over the phone. He simply didn’t believe me at first—how could an ordinary cargo barge be so enormous?

At Maine Maritime Academy, we learn a great deal about cargo on large vessels—ships carrying 16,000 containers or 2 million barrels of oil. But the world of barge cargo is more obscure.

At Western Towboat, where I spent my summer, we towed a small variety of barges—not to be confused with a variety of small barges. They are small only by comparison with the gargantuan ships of international shipping.

Handling cargo on these barges varies with size and type. We operated bulk barges for gravel, sand and other loose goods; we also operated ordinary container barges, with containers stacked as many as six high (over 60 feet above the deck). And the most interesting by far are the rail barges on the Alaska Railway deliveries between Seattle and Whittier, Alaska.

But it’s nearly impossible to convey the size of these barges. If I told you that the rail barge (the largest we tow) is 420-feet-long, that number wouldn’t mean much. But if you pictured nine school buses lined up end-to-end, you might be able to visualize it. Such a barge is wide enough to fit eight sets of rail tracks that run the length of the deck, and fits 32 rows of containers on scaffolding above those.

As soon as the shore ramp touches the deck, a scramble of activity ensues as about 20 longshoremen—people who physically handle cargo—swarm the barge with hammers and lashing tools. They get to work on the braces and chain lashings that keep the rail cars locked tightly to the deck.

I ran alongside them, trying to swing a hammer in a space between cars so tight even my skinny frame barely fit. After doing this 16 times (each track has space for about eight cars, two lashings on each side of the cars), I sat on the concrete for a second just to breathe.

Cargo has to be quick in all shipping. Time is money in this world, so the more time you save, the happier your employers are.

Previously, I’ve written about navigating a barge through the Wrangell Narrows. There are skegs in the stern of the barge that help guide it in a straight line, a useful feature for towing long distances. But to counter this forward motion in a tight channel, the barge must be ballasted properly so that there are 4 feet of “rake,” or drag in the stern.

When we finish handling the cargo, a mate goes around to each corner of the barge and reads the draft marks, which indicate how deep the barge sits at that spot. If the forward marks read 15-feet, 6-inches, then the after marks must read 19-feet, 6-inches. If they don’t, ballast tanks in the barge can be filled or emptied to change the draft.

Cargo in all shipping is similar, but there are unique aspects of barge shipping that big ocean ships don’t necessarily see in their daily work. That’s part of the specialized fun of the tug-and-barge world.

Benjamin Stevens of Islesford (Little Cranberry Island) is in his third year at Maine Maritime Academy in Castine.