Terrapin Electronic upgrade: Part III

Otto Von Helm

Otto is our third crewman.  He steers the boat for us when we are not able to take the helm, for whatever reason.  Otto is a computer that receives input from various sensors and then steers the boat based on criteria set by one of the human crew.  We can tell Otto to steer to a particular compass heading.  We can tell Otto to follow a particular route entered into the Zeus 2 chartplotter.  We can tell Otto to keep the boat at a particular angle to the wind for optimum sailing.  How does Otto do this?  Otto is a B&G NAC2 computer linked to the Zeus 2 MFD via the N2K backbone for the control interface, and a motor that drives the steering wheel via a belt.  Otto receives a variety of data from various sensors also  connected to the N2K backbone.  This includes wind speed/direction, compass heading from the Precision 9 compass, and rudder angle from the rudder angle sensor. 

The Precision 9 compass is the key to allowing Otto to know which direction the boat is pointing.  While we have a great gimballed compass at the helm, it is not electronic and does not provide any information to Otto.  The Precision 9 is a fluxgate compass (electromagnetic) that provides heading and rate-of-turn information to the N2K network for use by the autopilot, radar and other algorithms within the Zeus2.  It has an internal array of solid state sensors that can measure motion and orientation on 9 axes.  So Otto always knows exactly which direction the boat is headed.  To maintain a particular heading, Otto sends a command to the motor to turn the wheel, which is attached by a chain/cable mechanism to the boat’s twin rudders.  However, Otto also needs to know which direction the rudders are pointing: straight ahead, 10 degrees to port, or some other direction.  This is accomplished by a rudder angle sensor that I installed in the stern attached to the rudder control mechanism.  The rudder angle information is then sent to the N2K backbone. Finally, we can also tell Otto to keep the boat at a particular angle relative to the wind.  For this, Otto uses the wind direction information provided by the wind vane at the top of the mast through the N2K network. All of this can be controlled by the autopilot function on the Zeus 2 MFD.    The autopilot is an essential piece of gear for any long distance cruising. It can get very tiring manually steering a course for hours at a time, and generally Otto can do it better.  This allows the helmsman to keep a better watch or attend to other things like sail trim./ 

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