Simrad AP27, AP26 manual Depth Offset, Automatic tuning

Simrad AP26 and AP27 Autopilots

Depth Offset

Note ! This adjustment only applies to “smart” depth transducers that outputs depth on NMEA2000 format. NMEA0183 sentence ‘DPT’ contains offset and the depth reading is from the surface. NMEA0183 sentence ‘DBT’ contains no depth offset and the reading will be from the position of the transducer.

When the depth offset is set to zero, the indicated depth is from the transducer to the bottom.

To read the depth from the water surface to the bottom you have to set the depth offset according to the vertical distance between the surface and the transducer, i.e. positive (+) value. If you want to indicate the depth from the keel to the bottom you have to set the depth offset according to the vertical distance between the transducer and the keel, i.e. negative (–) value.

Automatic tuning

Automatic tuning is a feature that automatically sets the two main steering parameters (Rudder and Counter Rudder) by taking the boat through a number of S-turns. The scaling factors of the parameters are also set automatically as a function of the boat type selection performed in the Dockside menu.

Automatic tuning is an optional procedure that is not required for the autopilot to function. The autopilot is preset with steering parameters that should steer most boats in the 30 - 80 foot range. It is, however, recommended to perform an automatic turning as part of the sea trial.

Recommended speed during Automatic tuning varies with the type of boat, but should not exceed 10 knots.

Note ! Automatic tuning should not be performed at planing speed!

For displacement boats use a speed that is approximately half the normal cruising speed (i.e. if cruising speed is 10 knots, perform the Automatic tuning at about 5 knots).

The parameter values calculated during Automatic tuning becomes the HI parameters. The LO parameters are automatically set to 66% of the HI.

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