For Raytheon / Autohelm refer to table below.

Raytheon Mechanical Steering Specifications

For Simrad mechanical pilots refer to the rudder torque calculation sheet below. (This can be complicated. Fill in the blanks below, contact us, and we'll do the rest.)

Simrad Rudder Torque Calculation Sheet
For Mechanical Steering

The following questions must be answered in full in order to determine the rudder torque required to steer your vessel.

Size of Vessel: __________

Maximum Displacement of vessel (loaded): ___________

Maximum Speed of Vessel (knots): _________________

Number of Degrees of Rudder Deflection
(Hard Over to Hard Over): ________________

Voltage Available: ___________

Average Rudder Height (RH): ____________

Average Rudder Length (RL): ____________

Length of Counterbalance (CB): ___________

Number of Rudders: ___________

Use the formula below and the values above to calculate rudder torque.

Formula:
(RH) x (RL) x (RL - (2 x CB)) x (SF) = Torque in inch-lbs.

Note: For vessels with 2 rudders, double answer.

Calculation from formula:

After filling in all the blanks and following the formula, you should have the required ruuder torque needed for your autopilot. Cross reference your rudder torque requirement to the chart below and you will see what drive type you need.

Find the torque needed on the following Table 2.5 (next page) and the nessesary Simrad drive unit. Also find the speed factor (multiplexer) below Table 2.6

Table 2.6
Speed Factor Table

Table 2.5
Simrad Hydraulic Liner Drive Specifications