Coach Clemens began his rowing career in Germany in the mid-1970's winning several gold medals at the German Scholastic and Junior Championships in the single, as well as, doubles and quads. In 1978 and 1979, Clemens won the Junior Single event at the Thames Head Race in England. He was part of the German Junior National Team and trained with world champion sculler, Peter Micheal Kolbe. In 1979, Clemens medaled gold for Germany at an International Youth Regatta in Villach, Austria.
He began coaching for the Ruderverein Wandsbek, Hamburg, in 1981 and completed his Coaching-B license from the German Rowing Association in 1983.
In the United States, Clemens has coached youth rowers, collegiate rowers, and masters rowers at the Nereid Boat Club, the Passaic River Rowing Association, and Don Bosco Preparatory High School. In 2008, he became the Head Coach of the Teaneck High School Crew Team. In 2009, he gave guidance to students at Fairleigh Dickinson University in starting a new crew team, and became the volunteer crew coach for FDU. In response to a request from the Leonia School District he provided know-how and coaching in starting a new crew team at Leonia High School in 2011, and is developing new rowing programs for Teaneck Rowing Club since the summer and fall of 2010. In 2014, Coach Clemens assisted Coach Demetrio Gagnon with the Bergen Catholic Crew Team, and became the Head Coach in 2015. He also founded the Bergen County Rowing Academy in the Spring of 2014. He holds coaching certificates from the German Rowing Association (Deutscher Ruderverband Level B) and the U.S. Rowing Association (Level 2). Annually, he attends the Joy of Sculling Coaches Conference and the USRowing Advanced Coaches Conference to further educate himself as a coach.