Along the Cooper River in North Charleston, dozens of students spend eight-hour days learning about mixed gas diving, ship husbandry and underwater welding. 

They're working toward certifications as commercial divers, a field that, though small, sees a high demand for skilled workers. 

Less than two years ago, North Charleston's International Diving Institute was teaching courses to about 60 students a year. Now, it's closer to 200, said Michael Hielscher, the co-owner and director of the for-profit technical school. 

A newly renovated and expanded school facility on the old Navy Base in North Charleston opened early last month. Carver Construction, whose president is a co-owner of the school, completed the project, which included new classrooms, offices and workshop space in the roughly 24,000-square-foot building. 

The school was previously on Pierside Street along the Cooper River. The new location is on Avenue F on the old Navy Base, near the Lowcountry Innovation Center. 

At a brief ribbon-cutting ceremony last week, North Charleston Mayor Keith Summey praised the school for investing in a "vision" for the former Navy base.  

The three-mile-long campus was shuttered by the federal government about 25 years ago, but recent redevelopment has brought at least 4,000 workers to the area. Still a work in progress, that uptick in activity has included the movement of several other companies, nonprofits and government agencies to the former military installation. 

The next phase of the school's expansion, Hielscher said, will be the construction of new dormitories for students. It will include a full kitchen so students can eat, sleep and attend their classes in the same area during the intensive four-month program. 

The school is one of just three on the East Coast that offers commercial diving and underwater welding training, and its graduates have found work with a more than 90 percent success rate. 

According to the most recent data from the Bureau of Labor Statistics, the median income for commercial divers in the U.S. is close to $25 an hour and $50,000 a year. The top 10 percent in the field make more than $100,000. 

Students come from across the country to North Charleston, Hielscher said, and the same is true for recruiters. West Coast companies fly out to the facility to snap up top-performing students even before they've finished their training, he said. 

"There's such a high demand, we can't even fill it," Hielscher said. 

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Graduates are certified to work internationally, but many stay in the area. About a third accept jobs in the Carolinas, Hielscher said. 

More than half of the students are veterans, many of whom use their military benefits to complete the training without any out-of-pocket cost. Hielscher himself served in the Danish Navy, and he said the school and career path has been a good fit for many veterans, who tend to be particularly prepared for the intense physical demands of the work. 

The first part of the program is in the classroom, where students learn safety practices and the math and science behind the work they'll do underwater. Students who go on to learn underwater welding also learn topside welding in the school's workshop.

Diving practice starts in large tanks that are 20 feet wide and 20 feet deep at the training facility. By the end of the program, Hielscher said, divers are certified up to 190 feet. Deeper diving practice happens in the river and at Lake Murray near Columbia. 

Hielscher said he hopes to use their training facility to offer additional welding education that's unrelated to commercial diving, particularly if the school can partner with Charleston-area companies to provide training specific to their needs. 

Reach Emily Williams at 843-937-5553. Follow her on Twitter @emilye_williams.

Emily Williams is a business reporter at The Post and Courier, covering tourism and employment. She also writes the Business Headlines newsletter, which is published twice a week. Before moving to Charleston, her byline appeared in The Boston Globe.