Page 115 - Electronic Navigation Cyber Book

1. Rate of Turn and Rudder Limits
The method of turn is the most important control of the Auto-Pilot
system. The system will use the selected turn method for course
alterations. The user can input the limit of such turn methods, which
are as follows
a. Rate of Turn

This is the most commonly used turn method. In this method, the user
can set a value of turn rate between 1-300 degrees (varies on different
models). When turning, the rudder will move as much as it takes to
attain the required turn rate without exceeding the set value. The
officer must consider the vessel’s maneuvering characteristics and set
a value safe for the vessel.
b. Rudder Limits

Rudder limit method allows the user to set a value from 1 degree to
the max rudder angle. In this method, while altering course the rudder
will not exceed more than the set limit. Again, the vessel’s
maneuvering characteristics should be considered while choosing the
rudder value.

Modern systems allow turning by radius as well. In such method the
user can input turn radius in nautical miles.

2. Steering Gear Pumps
Steering gear pumps are used to pump hydraulic oil to actuate the
steering gear unit (RAM) which in turn moves the rudder in the
required direction. That means, when more pumps are running, the
rudder will move more swiftly. The number of pumps available varies
as per the steering gear unit.
The officer of watch should be aware of the pumps and use it wisely.

If operating the auto-pilot in areas with traffic density where sudden
and swift alterations are required, maximum steering gear pumps shall
be running.

In ocean cruising and open sea navigation with less traffic, the pumps
running shall be reduced to its minimum.

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