Years ago someone sent me a picture of a plate that they made to mount the transducer to (not a Side Imaging transducer but the big 3D transducers we made). On the back side of the plate were four of the suction cups. They claimed that it would stay on at speeds up to 40mph in smooth water. The plate had a rope that was tied to a cleat on the boat in case the suctions cups did not hold.