A comparison of the Virtual Environment Training Technology (VETT) shiphandling simulation at the Naval Air Warfare Center Training Systems Division (NAWCTSD) in Orlando, FL with the Maritime Surface/Subsurface Virtual Reality Simulator (MARS VRS) development system at the Defence and Civil Institute of Environmental Medicine (DCIEM) in Ontario, Canada found similarities in the technology used by the systems. The basis for these similarities is the natural interaction immersive technology provides for shiphandling. Both systems use a comparable head mounted display (HMD) for the visual scene, however head movements are tracked with dissimilar technology. VETT hardware includes an inertial tracker so that it can meet the requirement for shipboard use. MARS uses a magnetic tracker, allowing for 6 DOF to accommodate for movement used in real world performance. This hardware difference is compared. Necessary environmental fidelity is directly related to training objectives. Both systems create an environment to develop "seaman's eye", a perceptual skill used by shiphandlers. However, due to the differences in the specific shiphandling exercises used in the simulations, the fidelity requirements of environmental cues are different. VETT implements an underway replenishment (UNREP) maneuver, an exercise in which ships operated in close proximity, requiring detailed environmental cues such as waves and wakes. MARS VRS is used for performing training maneuvers completed at safe distances, precluding the necessity of high fidelity wakes. These differences are compared. VETT represents navigational information in numeric/abstract format on an HMD for voice call-up by the student. MARS uses high fidelity and real world representation of actual navigational instruments. The navigational information displays are compared. Unique to VETT is the collection of automatic performance metrics for correlation with subject matter expert (SME) ratings. Some preliminary findings are discussed. Conclusions are drawn regarding the differences in the systems and the implication for design of operational shiphandling training systems using virtual reality HMDs.