Anton Nauheimer will turn 80 on Thursday, and if you want to find him, the simplest place is still the one he has favored for years: the landing stage at the Eisernen Steg. The Frankfurt man, who has lived in Sachsenhausen, is still often seen on one of the five ships of the Primus-Linie, and he also makes regular stops at the office just a few steps from the water.

That routine is more than habit. Nauheimer took over the family company in 1974, carrying forward a business history that reaches back to 1880. In 2012, he handed operations to his daughter Marie Nauheimer, and the ownership was also transferred to her. Even so, he says he is still involved and, in his own words, still “immer noch an Bord.”

The Primus-Linie is a small, inventive business in Frankfurt’s corporate landscape, unusual in a city better known for finance and air traffic than for boat tourism. It runs trips in front of the skyline, but also sells after-work cruises and “Gruseldinner,” and sometimes goes farther afield to Mainz or Seligenstadt. Around 40 employees work on the five ships, with about as many temporary workers added in the season.

That business model also leaves little room for comfort. The company depends on the weather and on economic fluctuations, which means a sunny day can help and a weak economy can hurt. Nauheimer does not present himself as retired from that reality. He says his health is “Einigermaßen gut,” that he still engages himself in the Berufsgenossenschaft, and that he remains “immer noch an Bord.”

His family’s connection to the river goes back even further in living memory. Nauheimer says his great-grandfather once carried Schwanheim market women by ship to the Römerberg in the morning and back in the evening, a detail that fits the company’s long link to the Main and to everyday Frankfurt life. For all the changes in the city, he still says, “Ich genieße es, an den Mainkai zu gehen.” On Thursday, he turns 80, but the place that shaped his work still seems to be where he belongs.