Hi and
to the forum.
The only boat throttle I could find on the GM website was this one:
The controller should work with any 10k Ohm potentiometer type throttle or 5V Hall sensor type, but you would need to decide whether you require a single direction throttle and a separate reverse switch, or use a bi-directional throttle like the one shown above
(push forward to go Forward, pull back for Reverse, and Neutral in the mid position).The throttle shown above also appears to have a three position switch to select different power modes
(Economy, Normal and Sport).
Alan