Evolution Autopilot unable to hold course in waves

[Chuck - Raymarine - Moderator]

Willy,

The sea states which you are experiencing problems with may be exceeding the design for the Evolution autopilot, particularly for following seas.

There is very little you can do with an Evolution autopilot in way of adjustment. The only settings available to improve such performance would be Response, Rudder Damping and Vessel Hull type.

The important thing is to make sure the boat has the correct pilot and drive unit at the start and the pilot is set up correctly with regard to the drive type, vessel type and undertake the Dockside wizard. This will set the autopilot up for the boat type and steering characteristics. The pilot then knows the speed and up to what angle it can turn the helm. The set hard over time is important and is automatically set by the drive type and the helm angle.

The hard over time should be around 10 seconds or quicker. Too quick can cause helm instability and over activity. Too slow can cause under-steering and wandering. So with this boat it may be too slow. What is the hard over to hard over time for your autopilot? While slower response time may be alright in calmer weather, the helm needs to respond more quickly to the boat being pushed off course by the waves. Accordingly, should the hard over to hard over time be too slow, then the autopilot may not be capable of applying helm or counter rudder.

The vessel Hull type will make a difference as this sets the pilots characteristics to one of three boat models, for a mono sail boat this is only really two, Sail slow turn and Sail. You could try changing this setting to Sail as it will have an effect on the Gain and Counter rudder response.

Rudder Damping would help to stop over activity or s-ing ... I don't believe that this applicable.

The Pilot Response is the only adjustment you have while you are in Auto and it acts like a dead band. Leisure will open up the dead band and make the pilot less active and responsive to being off the auto course. If the sea is pushing the boat around you may not notice any difference in this setting. In Performance it will tighten up the response so should steer better but could make it too twitchy and have the adverse effect especially if the hard over to hard over time is too slow to keep up.

Again, performance under such sea states may exceed the design of the autopilot, but the above may help.