It is sometimes possible to enhance training effectiveness by departing from realism. As a general rule, however, in marine simulation, departures from realism are driven by limitations in training resources rather than a conscious attempt to optimize training effectiveness. The most notable exception is the initial development of manned models, a development borne out of practical necessity to safely train the prospective masters of very large crude carriers in shiphandling, which predates the research-psychology literature on training fidelity (Hays and Singer, 1989). As discussed in this appendix, the scaling inherent in manned models is believed by many to enhance training effectiveness, although there are concerns about the effect of scaling factors on individuals who do not have a well-established frame of reference in the operation of ships of the categories being simulated.
Because computer-based simulations rely primarily on software- based mathematical algorithms, there is considerable flexibility that could be used to deliberately depart from realism. In marine simulation, however, the opposite approach has been the rule. Most simulator facilities have sought high degrees of realism to build and improve confidence in simulation capabilities among mariners, training sponsors, and marine licensing authorities.
It is possible to alter the mathematical trajectory prediction models to accentuate certain vessel maneuvering behavior, for example, as an instruction technique to assist a trainee in becoming aware of a particular behavior. As a rule, such an approach is problematic, because it appears that only a few ship- bridge simulation staffs have reached the level of sophistication in instructional design and hydrodynamic modeling to effectively stage and control deliberate departures from realism. As discussed in a later section, there are strong reasons, from a hydrodynamic perspective, to avoid field adjustments to trajectory prediction models.
To understand how simulation modeling techniques differ and to better judge the level of trajectory modeling accuracy necessary for a specific training exercise, it is necessary to understand the phenomena that are being modeled. There are several primary areas into which a ship's maneuvering capabilities can be categorized: