Assessment of navigators’ ergonomic awareness and working conditions on navigation bridges

1.1.Ergonomics on a navigation bridge

Merchant ships can be considered as complex socio-technical systems, where mariners interact with technology designated for increasing the efficiency of operations [24]. Thus, it is important to constantly support the operator, as the technological progress advances. Human element is currently included in the Strategic Plan for International Maritime Organization (IMO) for 2018 to 2023. According to this, human element will be considered while reviewing, developing and implementing requirements and regulations. The well-being and needs of seafarers will be also taken into account by IMO [16]. Based on field observation, fatigue-related problems are common to seafarers nowadays, what can degrade cognitive skills, slow down reaction time or affect decision making [28]. Ships operate constantly around the clock and rely on watch patterns, therefore missing a proper rest and working in noisy, dynamic or stressful environment might seriously affect the performance of human. After taking over the watch, navigator is expected to provide the safety to the ship and maintain the highest level of focus.

Navigation bridge is the main command centre of the vessel and thus its key part [12]. Duties of a deck officer are complex and that is why workplace should provide adequate support to people, as described in International Convention for Safety of Life at Sea (SOLAS), Chapter V, Regulation 15 [13]. Those requirements are very general, however navigation bridge is additionally supported by non-mandatory standards and guidelines [27]. This includes but not limited to MSC/Circ.982: Guidelines on ergonomic criteria for bridge equipment and layout, IACS Recommendation No.95 for the Application of SOLAS Regulation V/15 – Bridge Design, Equipment. Arrangement and Procedures (BDEAP) and ISO 8468:2007 (Ship’s bridge layout and associated equipment – Requirements and guidelines). All of above-mentioned documents cover the topic of work environment factors, including lighting, temperature, humidity and noise. With the sole exception of noise limitation since 2012, so the adoption of Code of noise levels on board ships, there are only recommendations, guidelines and other non-mandatory documents regulating environmental conditions on the navigation bridges.

2.1.Questionnaire development

The questionnaire was developed based on the document MSC/Circ.982: Guidelines on ergonomic criteria for bridge equipment and layout, International Convention of Standards of Training, Certification and Watchkeeping (STCW), observations from own visits on different ships and consultations with experienced captains. Full questionnaire in English is presented in Appendix A. Due to the complex goals to be achieved in this research, questions were designed with various purposes, namely:

2.2.Sample and data collection process

The questionnaire was distributed in online form, along with another one, also related to bridge ergonomics, designed in a way preventing incomplete responses. The survey form could be filled whether in English or in Polish, accordingly to respondent’s preferences. The questions were the same in both languages, allowing consolidation of the answers after data collection process. The target respondents are very specific group of professionals, therefore to minimize the risk of bias and to obtain desirable level of confidence for this survey, it was deemed to be necessary to distribute online questionnaires via crewing agencies and shipowners.

The distribution started on 16 December 2021 and finished on 25 August 2022, resulting in 200 responses from the navigators holding the license of officer of the watch or higher. The participants were studying for their profession in 13 different countries. Each person was asked to fill the survey questionnaire once and all responses were checked manually to determine if they were filled correctly. It was found that one received form might contain doubtful or inconsistent answers, as the total time spent at sea in the rank of officer or higher, compared to the age of respondent, suggests obtaining such license before turning 18 years old, contrary to STCW requirements [14]. To achieve the highest quality of research, it was decided to remove this response from the analysis, so 199 were taken into consideration. The general characteristics of the sample are shown in Table 1.

2.3.Statistical environment and analysis

Analyses were conducted using the R Statistical language (version 4.1.1) [25] on Windows 10 pro 64 bit (build 19044). The significance level of the statistical tests in this analysis was set at α=0.05. The p-value was calculated using Holm’s correction method for multiple comparisons (padj). The distribution of measures of central tendency for numerical variables was expressed as median (the first quartile (25%), the third quartile (75%)) (Mdn (Q1, Q3)). For nominal variables, the distribution was determined by reporting the frequency of each category and the percentage of the total (n). The effect size for estimating the relationship between nominal variables was determined using the phi measure (φ). The significance of differences between the means of two independent groups for numerical variables was determined using the Wilcoxon rank sum test [29]. For three or more independent groups, the Kruskal–Wallis rank sum test [20] was used. The significance of differences between pairs of groups was tested using Dunn’s test [6]. For two categorical variables, significance was tested using Pearson’s chi-square test [23] or Fisher’s exact test [9]. Multiple comparisons for post-hoc tests were performed using the method of Benjamini and Hochberg [3].

3.1.Pain episodes during or after duties

Back pain, knee pain, shoulder pain or muscle pain were experienced by 82 (41.2%) navigators in a relatively young age group (Mdn = 34.0 years (Q1=27.0, Q3=48.8)), with a total sea time in the OOW/CO/Master ranks below the sample average (Mdn = 5.9 years (Q1=2.0, Q3=12.0)). Only 31 (37.8%) of subjects in the group with pain episodes reported that the navigation bridge met their expectations for comfort. This percentage was significantly lower than in the group without pain episodes (n = 74, 74.0%) (padj<0.001, φ=0.37).

Those with pain episodes were also significantly more likely to report too loud and irritating sounds (alarms, GMDSS communications, etc.) on the bridge than in the group without pain episodes (padj=0.039, φ=0.32). Pain in head, eyes, neck were experienced by 77 (38.7%) subjects in a relatively young age group (Mdn = 33.0 years (Q1=28.0, Q3=41.0)), with a total sea time in the OOW/CO/Master ranks below the sample average (Mdn = 5.0 years (Q1=2.0, Q3=10.0)). 57.1% of these people also suffered from pain in the back, knees, shoulders and muscles.

More than half of those with pain (n = 43, 52.4%), reported being overloaded during navigation watch and tasks such as constantly adjusting the brightness of equipment or adjusting the volume/temperature were annoying/distracting for them. This proportion was significantly higher compared with those without pain (padj<0.001, φ=0.32). Only 33 (42.9%) of subjects in the group with pain episodes reported that the navigation bridge met their expectations for comfort. This percentage was significantly lower than in the group without pain episodes (n = 72, 68.6%) (padj=0.002, φ=0.26).

3.2.Work environment and most disruptive factors

Different types of vibrations can be experienced onboard vessels, high-frequency vibrations are often related to rotating mechanical equipment, while low-frequency can be also caused by vessel motions on waves [1]. Rolling (n = 103, 51.8%) and vibration caused by machinery (n = 42, 21.1%) were mentioned among the greatest distractions while working on the navigation bridge. The disruptive factors were not significantly associated with the other sample variables. Loud or annoying noises were reported by 174 (87.4%) respondents, including loud noise alone by 34 (17.1%) and annoying noise alone by 66 (33.2%) subjects, both types of noise were reported by 74 (37.2%) subjects. Absence of noise annoyance was pronounced in the group of individuals with significantly shorter time as OOW/CO/Master (Mdn = 5.0 years (Q1=1.0, Q3=8.5)) compared with time as OOW/CO/Master of individuals with high noise levels (Mdn = 12.0 years (Q1=4.2, Q3=21.0)) (padj=0.040), as well as with the time spent in ranks of OOW/CO/Master by individuals who had high levels of both types of noise annoyance (Mdn = 9.0 years (Q1=4.0, Q3=21.5)) (padj=0.040). The total sea-time mentioned above together with an estimate of the differences between the groups is presented in the Fig. 2.

Fig. 2.

Total see-time in ranks of OOW/CO/master by answers to the question “Do you feel that sometimes on the bridge it is too loud or sounds there are irritating (for example because of alarms or GMDSS communication)?″ together with an estimate of the differences between the groups.

Those who reported loud noise along with disruptive noise indicated that their expectations of comfort while working on the bridge were significantly lower (n = 32; 43.2%), compared with the group that reported no noise (n = 23; 92.0%) (padj<0.001, φ=0.43). Also the percentage of comfort with reporting disruptive noise only (n = 39; 59.1%) was significantly lower (n = 32; 43.2%) compared with the group that reported no noise (padj=0.007, φ=0.32). Those who reported loud noise along with annoying noise reported significantly higher levels of fatigue (n = 60; 81.1%) compared with the group that reported no noise (n = 12; 48.0%) (padj=0.016, φ=0.35).

The lack of ability to regulate the temperature on the bridge was reported by 45 (22.6%) subjects, in addition to the lack of knowledge on this subject by 5 (2.5%), mainly elderly (Mdn = 58.0 years (Q1=34.0, Q3=58.0)). In addition, 32 (16.1%) respondents stated that the air conditioner works too hard, despite the possibility to regulate the temperature. In this group, there was a significantly higher proportion of subjects (n = 18; 56.2%) who reported the temperature difference between the height of the feet and the height of the head, compared to the group with properly functioning air conditioning (n = 25; 21.4%) (padj=0.002, φ=0.32). The ability to regulate temperature depended on the type of vessel. Local bridge temperature management was most frequently lacking on passenger ships (n = 6; 60%), a proportion was significantly higher than that of offshore vessels (n = 0; 0%) (padj=0.022, φ=0.73) and wet vessels (n = 19; 21.8%) (padj=0.017, φ=0.42).

Differences in the air in terms of humidification from a comfortable level were reported by 115 (57.8%) navigators, of whom 7 (3.5%) stated that the air on the bridge was too humid, for 49 (24.6%) the air was considered too dry, while for 59 (29.6%) both of the above cases were reported. The differences between the level of humidification and the comfortable level were significantly dependent on the level of comfort while working on the bridge. Namely, the percentage of comfort expectations fulfilled when the air was optimally humidified (n = 62; 73.8%) was significantly higher than when the air was too dry (n = 21; 42.9%) (padj=0.004, φ=0.31) or too dry and too humid (n = 30; 50.8%) (padj=0.023, φ=0.24). When the air alternated between too dry and too humid, navigators reported fatigue significantly more often (n = 48; 81.4%) than when the air was optimally humid (n = 52; 61.9%) (padj=0.040, φ=0.26).

A noticeable temperature difference between head and leg height was reported by 58 (29.1%) subjects. Such situation was not dependent on the type of ship and was mainly related to the operation of the air conditioning system. A noticeable temperature difference was significantly more frequent (n = 18; 31.0%) in a very strongly operating air conditioner compared to a normally operating one (n = 14; 9.9%) (padj=0.002, φ=0.32). Those who worked under conditions of greater temperature variation were significantly more likely to report fatigue (n = 47; 81.0%) compared to those who worked under normal conditions (n = 94; 66.7%) (padj=0.035, φ=0.19).

3.3.Bridge ergonomics versus fatigue

Potential increase of fatigue due to less than optimal conditions on the bridge were reported by 141 (70.9%) navigators. The degree of fatigue did not depend on age or total time spent at sea. The group with fatigue symptoms was characterized by a significantly lower degree of fulfillment of the individual needs of such a bridge in terms of work comfort (n = 71; 50.4%) compared to the group of subjects without fatigue symptoms (n = 30; 85.7%) (padj<0.001, φ=0.29). As mentioned earlier, fatigue levels were affected by, among other things, levels of loud and distracting noise (due to alarms or GMDSS communications), air on the bridge that was too dry or too humid, and temperature differences at leg and head level.

The degree of awareness that various ergonomic factors on the bridge have an impact on the effectiveness of your work and the safety of the ship was significantly higher among those with fatigue symptoms (n = 131; 92.9%), than among those without fatigue symptoms (n = 27; 77.1%) (padj=0.015, φ=0.23). The proportion of affirmative responses in the fatigued group to the question of whether task overload during navigation watch and tasks such as constantly adjusting the brightness of equipment or adjusting the volume/temperature were annoying/distracting was significantly higher (n = 75; 53.2%) compared to the non-fatigued (n = 9; 25.7%) (padj=0.008, φ=0.28).

An influence of various ergonomic factors on the bridge on the effectiveness of the work and the safety of the ship was found by 175 (87.9%) respondents. The distribution of affirmative responses did not differ by rank, license, age, time at sea or by vessel type. Those who were aware of the effects of ergonomics on job performance were more likely to report that uncomfortable working conditions on the bridge affected fatigue levels (n = 131; 74.9%) than the group who reported no effects of ergonomics on job performance (n = 5; 45.5%) (padj=0.018, φ=0.25) and those who had no opinion (n = 5; 38.5%) (padj=0.009, φ=0.29).

Frequent adjustment of work environment on the bridge was considered to cause overloads while working on the bridge or described as annoying/disturbing by 148 (74.4%) navigators. Those who reported overloads were significantly more likely to report the presence of muscle, back, or joint pain (n = 43; 46.2%) compared to those who did not report overloads during duty on the bridge (padj=0.004, φ=0.32). The groups of individuals who reported being overloaded (n = 44; 47.3%) generally had significantly lower levels of fulfillment of individual expectations for comfortable working conditions than those who did not report being overloaded (n = 37; 78.7%) (padj=0.003, φ=0.30). The same was true for fatigue level, which was significantly more often reported in overloaded conditions (n = 75; 80.6%), than in comfortable working conditions (n = 25; 53.3%) (padj=0.010, φ=0.31).

3.4.Training and willingness to study ergonomics

Mostly, the navigation bridge was considered a place that requires increased activity of the senses (n = 139; 69.8%), significantly less often as the place where navigators can rest (n = 38; 19.1%). A minority (n = 22; 11.1%), primarily older individuals with longer total time in the ranks of Officer Of the Watch, Chief Officer or Master, could not characterize their attitudes toward working on the bridge, it is shown accordingly in the Fig. 3 and Fig. 4. The characteristics of work on the navigation bridge did not depend on the rank, license of the respondent or the type of the ship. In contrast, those who characterized bridge as a place that requires increased sensory activity showed significantly greater interest in learning about ergonomics and its effects on work than the group who could not characterize their attitudes toward bridge work (padj=0.002, φ=0.30).

Fig. 3.

Age distribution of respondents by answers to the question “Is the bridge a place where you can calm down/quiet your mind or a place which requires an increased activity of senses?” together with an estimate of the differences between the groups.

Fig. 4.

Total see-time in ranks of OOW/CO/master by answers to the question “Is the bridge a place where you can calm down/quiet your mind or a place which requires an increased activity of senses?” together with an estimate of the differences between the groups.

Ergonomics training related to the bridge ergonomics was attended by 52 respondent (26.1%), of whom 35 (17.6%) had received such training at a college, university or courses. Willingness to learn about the concept of ergonomics and ergonomic implications for work was expressed by 157 (78.9%) individuals. The proportion of navigators willing to do so was similar regardless of rank, license type, age or total sea-time. In contrast, the percentage of those willing to learn who worked on wet ships (n = 79; 90.8%), was significantly higher than the percentage of those who worked on dry ships (n = 62; 66.7%) (padj=0.001, φ=0.46).

Those interested in ergonomics were significantly more likely to consider the bridge a place requiring increased sensory activity (p=0.001, V=0.27), also more likely to give correct answers regarding the brightness level outside/inside for the best observation (p=0.049, V=0.20). In summary, only 72 (36.2%) of respondents share the opinion that navigators comply with the ergonomic principles during the watches on the bridge.

3.5.Fulfilment of individual comfort needs on the bridges and employee loyalty

41.7% (n = 83) of the respondents stated that the navigation bridges do not meet the requirements for comfortable work, while more than half of them (n = 54; 65.1%) belong to the watch officer group. For the other positions (Chief Officer, Master or other), the majority pointed out that the requirements of the bridges are met in terms of working comfort. The degree of fulfilment of comfort needs did not depend on subjects age, total sea time in the OOW/CO/Master ranks or ship type.

For 128 (64.3%) respondents, adapting the bridge to individual ergonomic needs has an impact on loyalty and commitment to the company. These subjects were more likely to notice fatigue related to bridge working conditions. In addition, respondents in this group (n = 119; 93%), were significantly more likely to indicate that adapting the bridge to respondents’ individual ergonomic needs would have a significantly greater effect on their loyalty and retention to their employer than the group of respondents who indicated no ergonomic effect (n = 35; 76.1%) (padj=0.023, φ=0). Adapting the bridge to subjects individual ergonomic needs in non-comfort group would significantly higher affect their retention to their employer (n = 65; 78.3%). More than 70% of respondents with pain episodes said that adapting the bridge to their individual ergonomic needs would affect their loyalty and retention to their employer, only 15.9% said it would have no effect on their commitment to the company.

Individuals with good knowledge of ergonomics reported a significantly greater impact on loyalty and commitment to the company when working conditions addressed individual ergonomic needs (n = 119; 68.0%) compared to individuals without ergonomics knowledge (p=0.025, φ=0.20). The effects of adapting the navigation bridge to individual ergonomic needs on loyalty and commitment to the company in the survey groups OOW (n = 63; 74.1%) and Chief Officer (n = 28; 71.8%) had significantly higher percentages of positive responses compared to the Master group (n = 37; 49.3%) with padj=0.018, φ=0.27 and padj=0.003, φ=0.29, respectively. The degree of loyalty was not related to a person’s age or total time at sea.

4.1.Shifting the needs to comfort and well-being

It should not be underestimated that 41.2% respondents experienced back, knee, shoulder or muscle pain, while 38.7% declared pain in head, eyes or neck during or immediately after duties on the wheelhouse. In both cases, the percentage of those who reported that navigation bridge met their expectation for comfort was significantly lower in groups that experienced pain, than in groups without pain episodes. Those issues might be related to intensive work, as 69.8% of navigators considered bridge as a place that requires from them increased activity of senses. Regardless the workload or required focus, 41.7% of respondents were not satisfied in their working conditions, as their workplaces did not meet their individual requirements for comfortable work. The factors that had impact on such statements might be related to improper lighting, lack of local temperature adjustment and loud or annoying noises. Some of the issues, like rolling or vibrations from machinery, are impossible to be completely prevented by the design of the wheelhouse, however efforts should be made to minimize their negative influence, for example with shock mitigation seats or floor mats. Moreover, navigators spend several hours continuously on the bridges during the watches, therefore the risks of ergonomic related problems are increased due to lack of breaks.

The important result obtained in this research is related to employee loyalty, as the market faces global shortage of qualified officers. Adapting the bridge to individual ergonomic needs would have an impact on commitment to the company for 64.3% navigators, as directly stated by respondents. That suggests that people tend to care for their comfort and well-being, having in mind that performing the job of navigator does not need to result in musculoskeletal disorders or headaches.

4.2.Training should be supported by the design

The fact that only 26.1% of navigators received any training in bridge ergonomics is thought-provoking in the shadow of low level of compliance with ergonomic principles during watches. The issue is to be considered as a global problem, as the respondents were professionals studying for their job in 13 different countries. This is however not only related to university or college courses, but also to employers. Shipowners are definitely capable to take proactive actions to eliminate dangers related to improper ergonomics on navigation bridges to support health of seafarers, reduce fatigue and promote good habits. Moreover, 78.9% of respondents reported willingness to study concept of ergonomics and ergonomic implications for work. This might suggest that seafarers would like to be guided more directly in the future and it might be reasonable to consider implementing ergonomics training in International Convention of Standards of Training, Certification and Watchkeeping (STCW). This might include not only theoretical but also practical exercises on navigation bridge simulators, commonly used worldwide. Navigators could be instructed how to properly menage their workplace subject to ergonomic needs and outdoor conditions, including adjustment of brightness, volume or temperature.

It is understandable that some of vessels, for example those built before adoption of ergonomic guidelines, might not fully support proper ergonomics. Therefore at least sufficient training should be provided to the navigators in order to minimize their fatigue and eliminate unhealthy habits. In recent years, a lot of emphasis has been put on technological progress of navigational equipment but it should be highlighted that to operate ship in a safe manner, human surrounded by dozens of environmental factors should be capable of taking a proper decisions. One of the purposes of raising ergonomic awareness of navigators is to effectively manage the wheelhouse indoor environment in order to improve own performance.

Funding

This paper was made open access with financial support from Stichting Bijlboegfonds.

Conflict of interest

The author has no conflict of interest to report.

Author contributions

The author confirms sole responsibility of the following: conception; performance of work; interpretation of data; writing the article.