John “JT” Tiernan is in his second season as the head coach of the Gilmour Academy varsity boys and girls swim program, as well as the Lancer Middle School swim program, with the 2020-21 school year. In his first season directing the Lancers, the girls team finished fifth in the Ohio High School Athletic Association (OHSAA) Division II State Championship, after earning a North Coast League (NCL) Runner-Up finish. He was named 2019 NCL Coach of the Year.

He is an eight-year member of the Ohio High School Swim Coaches Association (OHSSCA) and was the former head coach of the girls swim team at Saint Joseph Academy from 2011-18.

The lifelong resident of Eastlake, Ohio, has been employed with the Gilmour Academy Natatorium for 10 years, and has been the youth swim coordinator for a year.