The Helmsman is the person who guides the hands of two people engaged in a "double dutch rudder". His/her Job is to control speed, tempo and emanation. The helmsman receives no physical stimulation and relies only on visual and auditory cues to guide.
Chaz: "hay Will, could you be the helmsman tonight for Lee and I"
Will: "hells no bro, I was the helmsman for Mikey and Bryan last night, it's your turn."