Darius Heumann, 5, showed he has no trouble speaking truth to power when a senior officer aboard the U.S. Coast Guard’s Healy icebreaker asked a visiting tour group “how many elephants do you think are aboard this ship?”

“Uh, zero,” Heumann piped up among the roughly 10 guests, including two of his grandparents, gathered in a control room of the vessel Friday afternoon.

Another visitor, deducing Lt. Cmdr. Ryan Konze was speaking figuratively about the ship’s weight, ventured a guess of 10,000 elephants. It turns out that was in the proverbial ballpark, with Konze noting the weight equals about 8,000 elephants — and it takes the power of 40,000 Formula One cars to make the engines and everything else function.

“We can power the equivalent of about a third of Juneau with what we have on board,” he said.

Perhaps due to his boldness — or just being the youngest member of the group — when the tour reached the bridge Heumann was picked from among the visitors to try his hand at the old-fashioned steering wheel. He was asked before the tour by his teacher to share what he learned with fellow students afterward and, perhaps not surprisingly, he said the steering wheel was the most memorable part of the roughly 30-minute visit.

[See also: Coast Guard icebreaker Healy stops in Juneau amidst fervor about homeporting newly purchased ship here]

The 420-foot-long Healy — the biggest in the Coast Guard’s fleet — is making a five-day stop in Juneau that ends Sunday following its most recent deployment to the Arctic, with the stop being extra notable this year due the Coast Guard recently announcing it will homeport a newly purchased icebreaker here.

Healy crew members ranging in rank from Ensign Brian Wheeler to Capt. Michele Schallip guided portions of the small-group tours aboard the icebreaker for two hours beginning at mid-afternoon Friday, during which hundreds of arriving visitors formed a steady line outside along one of the downtown cruise ship docks.

The tours generally avoided off-duty areas of the ship such as living quarters and the mess — but did visit a recreational space where everything from all-terrain bikes to weightlifting stations to a rugby ball were about — instead focusing on the vessel’s mechanical, operational and scientific functions.

As the elephant and Formula One references suggest, crew aboard the Healy were adept at explaining nautical and technical nuisances in layman’s terms. But they also delved into deeper details for visitors able to appreciate them, such as Konze explaining the icebreaker is built for power rather than speed with a top rate of about 18 knots.

“We make that usable power down below, we use that for punching through,” he said, adding that while the Healy’s official specs state it can travel at three knots through ice 4.5 feet deep he’s seen it break 12-foot-thick ice.

The Healy’s primary mission is providing support for polar region research activities conducted by visiting scientists. Among the contraptions shown to visitors in one of the ship’s many smaller rooms was a circle of attached tubes about four feet in diameter known as a CTD Rosette, with Wheeler explaining CTD stands for conductivity, temperature and depth.

“What this device does is we attach this to a crane and then we drop it into the water, and it goes through the water column these containers open up,” he said, referring to the tubes. “They take water in at different depths. We bring that water back up and then we can see a full vertical profile of the water column. We can see the salinity, we can see the temperature and then they can analyze the water samples for further information. So we do that at multiple points in the ocean and then that gives us a three-dimensional understanding of really what’s going on with all the different ocean currents.”

Some of the practical knowledge gained by such work was explained in the open air of a working deck, where Wheeler said the “meat and potatoes” of the Healy’s scientific activities take place. Data collected during the ship’s most recent voyage north this fall involves harmful algal blooms, which can cause shellfish poisoning.

“So being able to understand where that’s happening, how we might be able to predict that, and how we might be able to determine what the risk factors are can give people better insight into how they can make sure their food is safe,” he said.

That’s when Heumann piped up again with a question.

“What do shellfish do?” he asked.

Wheeler, responding to a query with a wide range of possible answers, told Heumann they’re “a broad category of ocean animal” such as clams and oysters that are “filter feeders.”

“They filter the seawater and, in that filtering process, they absorb nutrients so that they can eat,” Wheeler said.

Contrary to what Heumann might think after getting a turn at the steering wheel, personnel on the bridge said navigating the ship involves anywhere from three or four people under normal conditions to “a team of about 20 or so” through restricted coastal waters. In addition to typical mariner monitoring of things such as the weather and landscape, crew on the Healy’s bridge also may need to keep track of everything from ice conditions to scientific equipment in use to other duties such as search-and-rescue operations.

As the group Heumann was with prepared to depart the Healy, his grandparents Jim and Katherine both said curiosity motivated them to take the tour with their grandson since it was their first time aboard an icebreaker. Others leaving the ship offered similar reasons for being there, if somewhat differing things about what they found most memorable about the tour.

Samantha Kilmer, 15, said the only ship of comparable size she’s been aboard are the state ferries and in comparison “it’s a lot louder” aboard the Healy. Her brother, Zeke, 13, also noted the ferries are more civilian-friendly since “there’s more seating.”

And their mother, Amber, came away with more acquired knowledge about animals than just mythical elephants.

“It’s pretty embarrassing, but I just found out narwhals are real,” she said, noting they were among the wildlife crew members said they’ve seen at sea.

• Contact Mark Sabbatini at mark.sabbatini@juneauempire.com or (907) 957-2306.