Every Wednesday, the Hiram M. Chittenden Locks in Seattle, Wash., send the majority of the Western Towboat fleet out to sea. That’s “sailing day” at Western Towboat. The staff at the locks recognizes the company’s blue and yellow stacks that come through every week.

It’s a simple operation, despite what people may think. The Panama Canal, which has similar lock systems at each end, is much larger and can support vessels of massive size. But locks are much the same everywhere, and it’s a relatively simple concept.

A vessel traveling from Puget Sound to Lake Union must first get up to the inland elevation of the lake. To do so, it enters the locks at the ocean side; crew pass lines to the handlers on the walls of the locks. Doors in front of the boat hold back the waters of the canal above, which leads to the lake. Then the massive hydraulic doors shut tight behind the boat, and water is pumped into the lock. As the level rises, the boat floats upward until it reaches the level of the canal. Then the doors in front open, and the vessel travels out on its merry way.

The process is reversed for outbound vessels; they enter, shut the doors to the canal, and drain water from the lock to get the boat down to the level of the Sound.

For an operator on the tugs, however, there are other things to think about.

Water is extremely powerful, especially in the massive quantities contained in navigable waterways. I mentioned before that a 1 knot current puts many tons of force on a tug and barge; inside a lock filling with water, the pressure from filling creates eddies and swirls that act like miniature but powerful currents. The line handlers on deck must arrange their lines in a specific manner, so the pilot can come forward and take strain on the lines to counter the powerful forces of the water.

The lock is big enough to support a tugboat easily, but the caveat is the plethora of other boats in the locks—often operated by inexperienced yachtsmen and recreational motorists (who nearly always seem completely brainless when it comes to driving a motor boat). So make those lines tight, because you don’t want to scratch the paint on that $100,000 pleasure boat.

But there are hundreds of people every week who are not accustomed to this common sight. Tourists flock to the Chittenden Locks every day to see the fascinating process. They come with fanny-packs, cargo shorts (with crew length socks), cameras and weird sunglasses. If this doesn’t give you a good idea of our attitude towards tourists, just see my comment about recreational boaters above.

And they stare and stare and stare. It seems that whenever there’s an audience, a boat operator screws up the simplest tasks. Eventually, we got used to the spectators, but there were times when they really put us out.

One day, we were sitting and waiting for other boats to fill the locks, and the second mate tapped me on the shoulder. Pointing subtly, he indicated the two men standing side by side and staring straight at us from the lock walls. They were not 30 feet away and just staring at us. What was so interesting? They stood there for many minutes, just staring.

Then the chief mate saw us, and a wry smile caught his lip.

“I got this,” he said quietly, and disappeared into the wheelhouse for a moment. Then he reemerged with a pair of binoculars.

The second mate and I watched, eyebrows raised, as the mate raised the binoculars to his eyes and pointed them right at the two strangers who wanted to stare at us from so close. This staring contest was very short-lived. After a minute or so, the strangers started shifting uncomfortably—and then finally left as the second mate and I tried to stifle our laughter and be professional.

Benjamin Stevens of Islesford (Little Cranberry Island) is a third-year student at Maine Maritime Academy. Last summer, he worked on tugs in Washington and Alaska.