Rudders

To steer the boat, I designed two rudders controlled with servo motors. Each rudder can be raised when in shallow water. Since the completion of the rudders, the boat has been stable and very responsive to steering input!

CAD model showing the two rudders on the back of the boat.

The completed rudders installed on my boat. An outboard main engine was attached and fixed in place (no steering) to test the performance of the rudders.

The result of a preliminary simulation of the rudder.

The profile of the rudder blade was designed to limit the moment the servo and its gearbox needed to resist. See the simulation page for more details about how the center of the area was set.

Rudder Control

The rudder is electronically controlled. The controller box is shown below on the left; more details are on the PLC page. See the circuit design page for more about the guidance computer. There are three methods to steer the boat:

  1. Autopilot: Waypoint follower; the guidance computer completely takes over, but it can’t avoid obstacles (at least not yet).

  2. Semi-auto: The steering wheel sets the direction to move in, and the guidance computer keeps the boat on course.

  3. Full manual: Controlled with the steering wheel or touch screen.

Rudder and maneuvering thruster electronic controllers.

Control panel with the touch screen on the left, steering wheel in the center, throttle on the right.

Rudder assemble and parts

Below are some photos of the rudder’s parts being assembled.

All parts of the rudder (except the shaft) laid out.

Gearbox connected to the shaft.

Shaft in the main bearing support block. Note the shaft seal.

Videos of the rudder in action

Below are some videos of my rudder in action on the water and moving for the first time.

The rudder extended farther into the water than what it was designed for, kicking up a lot of water. This is due to the temporary outboard engine not initially reaching far enough into the water so I added a lot of weight to the back of the boat so the outboard engine could function for this test.

Rudder moving for the first time.

Rudder rotating for the first time.

Rudder lifting a weight.