[CA] [CA11] Explain any benefit of having gps data for Evolution autopilot

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum benzy,

Evolution autopilots are very much dependent upon speed data (Speed Through Water (STW), Speed Over Ground (SOG), or Cruise Speed) to maximize performance. Maximum performance will be achieved when accurate STW data is supplied to the autopilot to assist in compensating for current and wind leeway affects. Should accurate STW not be available or should the STW sensor suffer a failure, then SOG is the next best choice in supplying speed data to the system. As SOG is supplied by a GPS sensing device (ex. GPS sensor, MFD / chartplotter with internal GPS receiver, etc.) would typically be installed to support supplying the autopilot with SOG. In the absence of STW or SOG, the operator may enter an estimated Cruise Speed value to be used by the autopilot.

Recreational marine autopilots are designed to steer to heading (generally a magnetic heading), not to COG. GPS data in conjunction with chartplotting marine electronics and the navigational data they transmit are used be autopilots when operating in Track mode (i.e. going to a waypoint/cursor position or following a route).