6.1 Scenario description and objectives

　

 The STCW Code emphasises a thorough knowledge of and ability to apply the procedures of search and rescue operations. The following extract is an example (Figure 10) of an emergency return manoeuvre well known as the "Scharnow Turn" (see [4] and [5].)

　

 The Scharnow-Turn possesses some decisive advantages, e.g.:

　

　

 The main aim of this man over board manoeuvre is to return the vessel to the original track by the shortest route and with minimum loss of time. In practice the vessel initially follows the turning circle, and after shifting the rudder by a course change of about 240°,finally turns to counter rudder and amidships, the vessel then swings back to the opposite course at a certain measurable distance from the original track, respectively at a certain distance from the reference manoeuvre. The manoeuvring parameters which are used as reference values for evaluation of the Scharnow-Turn are given below in Table 5.

　

 For the simulation exercise a schedule has to be developed in accordance with the evaluation scheme described above. Table 3 gives an overview of the main groups and headlines of the evaluation scheme corresponding to the applicable actions and considerations for the simulation.

　

　

　

　

6.2 Assessment parameters and criteria

　

 Although a number of aspects could be considered for assessment, present investigation has focused so far on the main aspects only, that is, evaluation of returning the vessel to her original track and with minimum loss of time.

　

 The parameters are listed in Table 3. The manoeuvre has to be performed by three rudder positions, e.g. hard to STB, when the event is noted, hard counter-rudder to Port at about 240°course change from original course and meet the rudder with hard to STB again, before the vessel swings back to the opposite course. The rudder angle and the exact time of shifting the rudder are the most important parameters for the successful manoeuvre and for assessment. The overshoot angle at about 240° course change is an important parameter. Only if the value is taken accurately, it is possible for the trainee to swing back the vessel to the opposite course at the right time. The track deviation is the result of manoeuvre performance and one of the main parameters for assessment. The allowable distance from the original track is depending highly on the visibility conditions. Table 4 shows the identification distance at day or night time and for different hydro-meteorological conditions. The instructor has to decide and adjust the criteria limits for the simulation exercise according to the environmental conditions.

　

　

　

　

6.3 Exercise assessment using the evaluation tool

　

 In the example the acceptable area of return is marked as a rectangle with the limitation defined as the criteria limit. If the allowable distance from the original track is defined e.g. < 250 m (max deviation at daylight and good visibility) and time difference of arrival by comparison to the optimal returning point e.g.< 1 min, the criteria net shows if the vessel returned within the limits or shifted beyond. With reference to the computer based assessment two prospective paths will be researched in ongoing trials. It is possible to evaluate the results very roughly in either of two categories only:

　

・"applied with" (returning point within limits),

・"not applied" (returning point beyond limits),

　

 Alternatively, a more detailed pointing system may be used. This starts with the maximum number of points (returning on spot) and decreasing the number of points proportionately to distance removal from the criteria centre. If the vessel returns beyond the limits, penalty-points would be awarded.

　

 After finishing the exercise the manoeuvring values for assessment will be calculated by the evaluation tool. The values available are listed in Table 5 and will be available to the instructor immediately after the exercise run on the PC. According to the selected criteria of the concrete exercise - < 250m difference in cross distance and < 1 min time difference to the reference manoeuvre - the vessel returns within the criteria limits. In this example the negative value of returning time is related to the earlier return but before reaching the original track. Strictly speaking the time criteria is only applicable if the vessel would return and enter into the left part of the assessment field by overstepping the turning circle. In this simulation run trainee's performance can be evaluated as being "applied with" according to STCW 95 requirement.

　

 The output of computed results is shown in the right column of Table 5. The numeric values can be reviewed by calculation of significance. The last two fields in the table are the main criteria. Even in case of small deviations at the beginning but return into range of assessment field the result can be considered as successfully.

　

 As an object in view the evaluation tool should be used for both options relating to the type of manoeuvre, evaluation and assessment according to concrete criteria limits and/or for simulation exercises by comparing reference data with actual simulation results.

　

　

 For the reasons illustrated above it is apparent that computer based evaluation of simulation exercise runs are essential for the training of students and mariners. Not all necessary aspects that a simulator instructor should take into consideration can be measured or expressed as a quantified value for direct automatic CBE. In particular communication and individual situation-awareness aspects of bridge team member's actions are difficult to monitor and cannot be traced in the replay file after the exercise. However, for some of these crucial training elements and aspects it should be possible to find a "work around", i.e. methods to check the trainees response indirectly by other parameters.

　

 The developed software tool at the MSCW offering at least a part computer based assessment, gives extra support to the simulator instructor, who will also in future be indispensable, and it offers a more objective evaluation of the seafarer's proficiency according to STCW 95.

　

　

K. Benedict achieved his PhD's in Ship Dynamics and on Advisory Systems for Ship Operation. He is Professor/Senior Lecturer for Ship's theory and Vessel Traffic Technology and the Head of MSCW.

　

M. Baldauf obtained his Ph.D. in Safety Engineering and is presently employed as chief coordinator for research. He is involved in several projects dealing e.g. with AIS.

　

C. Felsenstein worked as Captain and received his Ph.D. in Nautical Engineering. He is engaged on two research projects dealing with problems of maritime training and education.

　

M. Kirchhoff took his diploma in the field of automation and control engineering. He is working on the development of the computer-based evaluation tool.