Simrad AP28 Autopilot Calibrations

After installing the Simrad AP28 autopilot system and before we can start using it we had to set up the autopilot and do some calibrations, all of which were pretty simple and well described in the installation manual.

When we turned on the autopilot system for the first time the control head screen displayed the system information, then the language selection screen was displayed and finally the AP28 control head went into the automatic data source selection process identifying all the data sources on the SimNet system including the autopilot components and the units that the autopilot was interfaced with. The selection process was quick and it did identify all the data sources without any input from me. Plug and play worked excellent.

After the data source selection I entered the Installation Menu where the calibration process and setting options can be accessed. The Installation Menu lists everything that needs to be completed and in the order it should be done. Navigating the menus on the AP28 is very easy.

First on the list in the Installation Menu is the Commissioning Page. The Commissioning Page is where the dockside and sea trial calibrations are accessed. After selecting the Commissioning Page I selected the Dockside Setup option. Here I had to setup the boat type (Sailboat), complete the rudder feedback unit calibration (followed on screen prompts in easy to understand instructions), select the drive voltage (12vdc), perform the rudder test and finally set the minimum wind angle for when sailing by wind angle (set to 50 degrees). The whole process took about 30 minutes to complete.

Next was the sea trial setup. For this we had to wait for a day that had light to no wind and as little current as possible. We also had to make sure that we had enough deep water around us to safely maneuver. The first step in the sea trial was to set the rudder center which required motoring at cruising speed in a straight line, then pressing a key to accept the rudder 0 position.

After the rudder was centered we calibrated the RC42 rate compass by turning the boat in a slow, wide circle. This took a minute and a half to complete. Our local field of magnetic interference was recorded at 11 degrees, higher than I expected but well within the tolerances of less than 30 degrees. While turning the boat in a circle the display shows a completion progress bar as well as an indication if one is turning too slow or too fast. The calibration is stored in the RC42's memory and won't need to be done. We do though calibrate our autopilot compass once a year just out of habit.
There are options to calibrate the wind direction from the mast head transducer and the boat speed from a paddle wheel transducer, neither needed to be completed in our installation during the sea trial.

Next we needed to set the Transition HI-LO value, the default setting was six and we set it to 3 which is recommended for sailboats. The Transition HI-LO is the speed at which the AP28 will automatically change the steering parameter from HI to LO or LO to HI depending on the boat's speed.

Automatic tuning sets the Rudder and Counter Rudder parameters by taking the boat through a number of s-turns but it is not a calibration procedure that is required for most boats. We went ahead and completed it anyway. It requires a fair amount of space to safely navigate while the autopilot turns the boat automatically to determine the best settings. During this process we needed to maintain a speed of about half our cruising speed. I think that for most boats the default setting should work fine and next time I would try it before completing this step, which can be done at any time.

This completed our dockside and sea trial calibrations. The instructions in the manual were very easy to follow and had excellent photos of what each menu looked like. The sea trial look less time than it did to raise and re-anchor. There is a status screen under the Commissioning page which will show which procedures have been completed and which have not. There are numerous settings that can be adjusted manually to fine tune the performance of the autopilot. Now that our new Simrad AP28 is calibrated we look forward to seeing how it performs and if necessary we'll make any appropriate adjustments. The AP28 is feature packed and after some use we'll post more about its performance, if it meets our expectations as well as its features. Stay tuned.