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3.1.3 Functions 
The fundamental functionalities assigned to this task are of the “set/actual comparison” type. They thus 
possess the following elementary individual functions: 
• Record set values 
• Record actual values 
• Compare set and actual values 
• Assess comparison 
• Provide result 
Annex 7.3.1 contains the functionalities identified for this task as well as the elementary individual func 
tions with their input and output data, in overview form. 
32 Determining set values 
The process of determining set values may be carried out both manually and automatically. Although 
establishing the degree of automation is not basically the content of functional analysis, distinctions must 
be made in this task: 
• Automatic track following is permissible only under certain circumstances. The as 
sessment criteria for this are the current range of the track, which must lie below a 
fixed limit, and the necessary course change to steer onto the track, which must not 
exceed a fixed limit value 
• Automatic and manual track following differ considerably in terms of their input data. 
Course changes in automatic track following mode are generally arranged by means of 
a set value for the ROT. In manual track following, the turning radius as a function of 
the manoeuvring room available is the deciding variable. 
These peculiarities are taken into account by virtue of the fact that a proportion of the input data is op 
tional, depending on mode. 
3.2.1 Purpose of task 
The purpose of the task is to determine set values for rudder angle and engine control in order to take 
the ship onto the planned track. By way of input data here, the resultant data from the task “Determining 
set/actual deviations” are used, i.e. the difference between the set data (from voyage planning) and the 
actual data (from the state identification). 
3.2.2 Functionalities 
When determining set data, the direction and speed of the ship are the deciding parameters. For this 
reason, a distinction is made between two global functionalities: “Set speed” and “Set direction”. 
The functionality “Set direction” essentially consists of three control functionalities (see Figure 3): 
• “Adjust heading”: the ship’s heading is adjusted to a set value. The setting variable is 
the rudder angle 5.