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This study examines mental workload and performance in simulated high-speed ship navigation. Two navigation methods were compared based on an electronic chart display and information system (ECDIS) and a conventional system using paper charts. Twenty naval cadets navigated in high-fidelity simulators through a 50 nautical mile course with varying levels of difficulty. Results showed that ECDIS navigation significantly improved course-keeping performance, but reduced the total amount of communication on the bridge. No differences were observed in subjective workload between groups. Heart rate variability and skin conductance measurements indicated higher workload in conventional navigation, but the differences between groups were not significant.

ABSTRACT.Purpose: This study reports contrast sensitivity (CS) reference values obtained by two different test methods in a strictly selected population of healthy, young adults with normal uncorrected visual acuity. Based on these results, the index of contrast sensitivity (ICS) is calculated, aiming to establish ICS reference values for this population and to evaluate the possible usefulness of ICS as a tool to compare the degree of agreement between different CS test methods. Methods: Military recruits with best eye uncorrected visual acuity 0.00 LogMAR or better, normal colour vision and age 18-25 years were included in a study to record contrast sensitivity using Optec 6500 (FACT) at spatial frequencies of 1.5, 3, 6, 12 and 18 cpd in photopic and mesopic light and CSV-1000E at spatial frequencies of 3, 6, 12 and 18 cpd in photopic light. Index of contrast sensitivity was calculated based on data from the three tests, and the Bland-Altman technique was used to analyse the agreement between ICS obtained by the different test methods. Results: A total of 180 recruits were included. Contrast sensitivity frequency data for all tests were highly skewed with a marked ceiling effect for the photopic tests. The median ICS for Optec 6500 at 85 cd/m 2 was À0.15 (95% percentile 0.45), compared with À0.00 (95% percentile 1.62) for Optec at 3 cd/m 2 and 0.30 (95% percentile 1.20) FOR CSV-1000E. The mean difference between ICS FACT85 and ICS CSV was À0.43 (95% CI À0.56 to À0.30, p < 0.00) with limits of agreement (LoA) within À2.10 and 1.22. The regression line on the difference of average was near to zero (R 2 = 0.03). Conclusion:The results provide reference CS and ICS values in a young, adult population with normal visual acuity. The agreement between the photopic tests indicated that they may be used interchangeably. There was little agreement between the mesopic and photopic tests. The mesopic test seemed best suited to differentiate between candidates and may therefore possibly be useful for medical selection purposes.

ObjectivesPrior studies have indicated a high prevalence of noise-induced hearing loss (NIHL) among Navy personnel; however, it is not clear whether this is caused by work on board. The present study aimed to assess the prevalence of hearing loss among Navy personnel in the Royal Norwegian Navy (RNoN), and to investigate whether there is an association between work on board RNoN vessels and occurrence of hearing loss.MethodsNavy personnel currently working on board RNoN vessels were recruited to complete a questionnaire on noise exposure and health followed by pure tone audiometry. Hearing loss was defined as hearing threshold levels ≥25 dB in either ear at the frequencies 3,000, 4,000 or 6,000 Hz. Hearing thresholds were adjusted for age and gender using ISO 7029.ResultsThe prevalence of hearing loss among Navy personnel was 31.4 %. The work exposure variables: years of work in the Navy, years on vessel(s) in the Navy and years of sailing in the Navy were associated with reduced hearing after adjusting for age, gender and otitis as an adult. Among the work exposure variables, years of sailing in the Navy was the strongest predictor of reduced hearing, and significantly reduced hearing was found at the frequencies 1,000, 3,000 and 4,000 Hz.ConclusionsOur results indicate that time spent on board vessels in the RNoN is a predictor of reduced hearing.

Seafarer's mental health is vital for a well-functioning organisation. Neglecting mental health status on board could be extremely costly for both the crew affected as well as the company. The present article outlines an extensive programme implemented in the Royal Norwegian Navy for personnel deployed in international operations. The challenges involved in international operations bare similarities to onboard personnel in civilian maritime operations. The program utilised by the Royal Norwegian Navy is extensive and not immediately applicable to civilian maritime companies. However, elements of this program could be used with limited resources. Questionnaire based screening, before, during and at the end of a contract period could result in early detections of mental health problems and increased retaining of personnel. This should be done by health professionals. Early targeting of at risk personnel could prevent serious costs for the individual as well as the company.