121

4.2.3  Voyage  execution
The  process  represented  in  DFD  2  models  the  execution  of  the  voyage.  On  the  abstract  level  represented ­
  here,  voyage  execution  can  be  modelled  by  two  processes:
-  “Determining  set/actual  deviations"  (Process  2.1):  determining  the  deviations  between  current  state
variables  (position,  courses,  speeds)  and  set  values.  Set  values  originate  from  the  following
sources:
1.  from  the  current  voyage  plan
2.  from  other  processes  within  integrated  navigation  -  particularly  Process  4  “Dealing  with  unplanned ­
  incidents”
3.  from  other  sources,  e.g.  instructions  from  vessel  traffic  services
-  “Determining  set  values”  (Process  2.2):  this  process  models  the  actual  control  process  (on  this  point,
see  also  part  A).  The  output  information  from  this  process  goes  in  two  directions:
1.  The  result  of  the  control  process  amongst  other  things  constitutes  set  values  for  courses  and
heading  (“Course/heading  controller”).  The  information  determined  in  this  way  goes  back  to  Process ­
  2.1.
2.  Process  2.2  supplies  the  central  output  data  flows  of  the  system  “integrated  navigation”,  i.e.  set
values  for  the  rudder  angle  or  set  engine  data.

DFD  2:  Task  area  “Monitoring  and  executing  the  voyage’