Mar 1, 2012 - 2.2 Study 2 â Human factors and lifeboat loading trials (Dartmouth):..................... 11. 2.2.1 Timing related data collection for lifeboat launches .
Technical Report to Transport Canada on Research Studies to Investigate the Impact of Immersion Suit Use in an Emergency Situation
C.J. Brooks1, J.W. Kozey2, S.L. Dewey2, R.C. Brown3, K.A. Howard1, D. Drover4, S. MacKinnon4 and J. McCabe2 1 Survival Systems Limited, Dartmouth, Nova Scotia 2 Dalhousie University, Halifax, Nova Scotia 3 Marine Institute, St. John’s, Newfoundland 4 Memorial University, St. John’s, Newfoundland November 1, 2004
Table of Contents 1
2
3
4 5 6
Introduction .................................................................................................................. 7 1.1 Objectives of this work.......................................................................................... 7 1.2 Study 1 – Structural Anthropometry (Dartmouth and St. John’s):........................ 8 1.3 Study 2 – Determination of lifeboat capacity and loading (Dartmouth only):...... 9 Methods and Procedures .............................................................................................. 9 2.1 Study 1 – Structural Anthropometry (Dartmouth and St. John’s):........................ 9 2.2 Study 2 – Human factors and lifeboat loading trials (Dartmouth): ..................... 11 2.2.1 Timing related data collection for lifeboat launches .................................... 12 2.3 Data Analysis....................................................................................................... 13 2.3.1 Study 1 – Structural Anthropometry (Dartmouth):....................................... 13 2.3.2 Study 2 – Human factors and lifeboat loading trials (Dartmouth): .............. 13 Results ........................................................................................................................ 14 3.1 Study 1 – Structural anthropometry – Survival Systems Limited, Dartmouth.... 14 3.1.1 Overall effects............................................................................................... 14 3.1.2 Shoulder breadth ........................................................................................... 15 3.1.3 Hip Breadth (standing).................................................................................. 15 3.1.4 Hip Breadth (seated) ..................................................................................... 16 3.1.5 Hip breadth seated versus standing............................................................... 16 3.1.6 Shoulder breadth to hip breadth (seated) ...................................................... 16 3.1.7 Overall effects of wearing the immersion suits ............................................ 17 3.1.8 Shoulder breadth ........................................................................................... 17 3.1.9 Hip Breadth (standing).................................................................................. 18 3.1.10 Hip Breadth (seated).................................................................................. 18 3.1.11 Hip breadth seated versus standing ........................................................... 19 3.1.12 Shoulder breadth to hip breadth (seated)................................................... 19 3.2 Structural Anthropometry – (St. John’s) ............................................................. 19 3.3 Comparing the data from the seafarers in Newfoundland and Nova Scotia data 20 3.4 Is there any correlation between body mass and shoulder, hip (standing) and hip (seated) measurements?................................................................................................. 21 3.5 Simulation model for lifeboat loading capacity .................................................. 22 3.6 Study #2: Lifeboat loading test to capacity ........................................................ 23 3.7 Loading time data ................................................................................................ 24 3.8 Loading Capacities in the lifeboats ..................................................................... 25 3.9 Physical Observations ......................................................................................... 25 3.10 Questionnaire data after each loading trial....................................................... 26 Discussion .................................................................................................................. 28 4.1 Structural anthropometric dimensions................................................................. 29 Conclusions & Recommendations ............................................................................. 30 References .................................................................................................................. 32
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Abstract This study was conducted in two parts. The first was to measure the physical size (height, weight, shoulder breadth, hip breadth (standing), hip breadth (sitting)) of two groups of seafarers in standard work dress and three typical immersion suits. The second part was to examine their fit into two lifeboats (one 36 person and a 50 person) when wearing work dress and then each of the three immersion suits. Four important findings were revealed. First, both populations of seafarers (one from Dartmouth, Nova Scotia and one from St. John’s, Newfoundland) are considerably heavier than the IMO Life Saving Code standard of 75 kg. Second, their shoulder breadths were always considerably greater than their hip breadths. Third, the seat pan allocation of 430 mm is not adequate for the seafarer population and needs to be increased, and finally, the wearing of an immersion suit increases the physical size of each seafarer. As a result of this study, IMO may wish to consider an international anthropometric study to update the LSA code in order to correctly represent the seafarer population in both the weight and space requirement. Finally, they should consider using shoulder breadth measurements instead of hip breadth measurements for space allocation.
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Executive Summary At the 47th session of the Design and Equipment sub-committee of the IMO (24 December 2003), a paper was submitted by China (DE 47/516) that demonstrated wearing an immersion suit reduces the effective human capacity of lifeboats. The Transport Canada contracted Survival Systems Limited, Dartmouth, Nova Scotia and the School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia to investigate the problem of change in seafarers’ structural dimensions when wearing an immersion suit on top of standard work clothes. The study was conducted in two parts. The first was to measure the physical size of two typical groups of seafarers working both in standard work clothing and three typical immersion suits, and second, to take a representative group of them and evaluate their fit in two different capacities of lifeboat when wearing standard work clothes and then in each of three immersion suits. One group of seafarers was measured at the Survival Systems Marine Training School, Dartmouth, Nova Scotia, and the second group at the Marine Institute in St. John’s, Newfoundland. The lifeboat fit study was done using a 36 person single davit lifeboat and a 50 person twin davit lifeboat in Dartmouth. The ethics committees at Dalhousie and Memorial Universities approved both experiments. Method: Study 1 – Eighty male and seven female seafarers were randomly selected from marine survival courses in Dartmouth, Nova Scotia and 84 others were randomly selected from marine survival courses held in St. Johns, Newfoundland. Each subject read the experiment protocol and signed an informed consent form prior to commencing the study approved by the universities’ ethics committees. Overall height and weight were measured and their body mass index (kg/m2) was calculated. To measure a comfortable and tight fit of the work clothes and the immersion suit, an enlarged, Harpenden anthropometer was constructed with the addition of a force gauge which could measure a comfortable fit (no compression) and a tight fit (2700 grams/6 lbs). Specific measurements taken were (a) standing shoulder breadth (bi-deltoid), (b) standing hip breadth (bi-trochanteric), and (c) seated hip breadth. The measurements were taken with the subjects wearing work dress and then one of three immersion suits. Additional calculations were made on the practical application of the data to the fit of the humans in the normal allotted space. This was accomplished by comparing the shoulder and hip breadths of a random sample of subjects to the linear space allocation of 430 mm prescribed in the IMO Life Saving Appliance Code. A simple mathematical model was developed to calculate the cumulative length of the row of seafarers compared to the value used in the standard. The seafarers were modeled on being seated side by side just touching each other, the cumulative length was the addition of the breadth measurements of each person as they are moved along the row.
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Study 2 – Fifty subjects anthropometrically matched to the seafarers that volunteered for Study 1 were recruited. Height, weight, shoulder and hip measurements were recorded. As in Study 1, the subjects wore work dress and individually, on top of this, each of the three suits worn in the anthropometric measuring study. Then 50 of the subjects were loaded or attempted to be loaded in the single hatch lifeboat, and 36 subjects were loaded or attempted to be loaded in the lifeboat with two hatches. Times were recorded for the first person to board, for the last person to board, time for the hatch(es) to be secured and last person to be securely buckled up. After completion of each loading test, the subjects were required to fill in a questionnaire, which asked (a) the ease or difficulty of moving to the seat, (b) the comfort and fit in the space allocation, and (c) the ease or difficulty in being able to lock or unlock the seatbelts. Results Study 1 (Anthropometry): General human information: The general physical data on both seafarer populations in Dartmouth and St. John’s were very similar and there was no significant difference between them. The combined data showed an age range from 18 to 62 years, a marine experience range from none to 34 years, a height range from 153.4 cm to 194.7 cm and a weight range from 46 kg to 145.5 kg. (The BMI calculation ranged from 17.9 kg/m2 to 45.7 kg/m2.) The overall average weight for the two populations was 88 and 86 kg and 85% of the seafarers weighed over 75 kg. The IMO uses a mean body mass criterion for lifeboat loading of 75 kg. Measurements in work dress (millimeters): The mean and standard deviation values for the shoulder breadth, hip breadth standing and hip breadth seated were 515 (38), 383 (26) and 419 (29), respectively. When compression was applied to the subjects these values changes to 441 (35), 322 (23) and 357 (28), respectively. Measurements in immersion suits (millimeters): The mean and standard deviation values for the shoulder breadth, hip breadth standing and hip breadth seated were dependent on the suit worn. •
The shoulder breadth values were 592 (38), 595 (31) and 604 (38) for the three different suits. In the compressed state, the values were 458 (33), 468 (39) and 472 (36).
•
The hip breadth standing values were 424 (27), 425 (29) and 427 (31). In the compressed state, the mean values were 327 (23), 335 (26) and 330 (23).
•
The hip breadth seated values were 452 (23) 459 (29), and 464 (25). In the compressed state, the values were 376 (30), 377 (29) and 380 (29).
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Not unexpectedly, the values for the shoulder breadth, hip breadth standing and seated recorded in the work clothing were significantly less than any of the measurements taken while wearing the immersion suits. Also, not unexpectedly, with compression (to represent a tight fit) all three measurements were significantly less than the uncompressed measurements and again, not unexpectedly, the compression had a significantly greater effect on the seafarers when wearing immersion suits. There was a much larger volume of material to compress. The IMO Life Saving Appliances 2003 edition code prescribes 430 mm for space allocation per person. The mean standing and seated hip breadths measurements in work clothes were less than this value. The mean standing hip breadth values (uncompressed) obtained in suits is equal to the value of 430mm. However, the hip breadth seated measurements, uncompressed exceed the value of 430 mm. Compression is required to reduce the mean hip breadths below the 430 mm criterion. (This is exactly what occurred in the lifeboats when everyone was squeezed in like sardines!) However, the most important finding is related to the shoulder breadth measurement. For instance in the Nova Scotia population, 85 of the 87 seafarers while wearing work clothes had a shoulder breadth measurement uncompressed, greater than the 430 mm. With compression but no suit, the value of 430 mm represents the 33rd percentile value (67% of the seafarers were greater than 430mm). All mean shoulder breadth measurements (with and with a suit and/or compression) exceeded the 430 mm. A comparison was made between shoulder breath and hip breadth (seated) measurements. In all cases in work clothing, the shoulder breadth was significantly greater than the hip breadth (seated) by an overall mean value of 90 mm. When an immersion suit was donned this increased the mean shoulder and hip breadth seated measurements by an overall value of between 105 and 123 mm depending on which suit was worn. This explains why the seafarers’ bottoms just fitted into the seat pan relatively comfortably in their work clothing and extremely uncomfortably in immersion suits, yet in both cases their shoulders could not be comfortably placed to fit squarely against the bulkhead. Results Study 2 (Lifeboat Loading test): In work dress: It was physically possible to load 36 people into the 36 person lifeboat but only 49 people into the 50 person lifeboat. In both lifeboats two problems were noted. First, no one could place themselves solidly in the seat with their shoulder blades parallel to the bulkhead. In each case, their trunks were rotated with one or the other shoulder pushed forward to allow the person on either side to do the same thing and fit in like a jigsaw puzzle. Second, the space allocation at the curvatures of the lifeboat required that each person’s knee had to be interlocked very tightly with the person opposite. In suits:
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Although there was considerable variability between the opinions expressed about wearing the immersion suits in the two lifeboats, the extent to which the subjects found that space to be satisfactory and comfortable is very low. For instance, the only instance in which more than 50% of the individuals were satisfied with space (64.7%) was when they were wearing only work dress and no immersion suit and were seated in the 36 person lifeboat. Only 29.8% of individuals reported they were effective in performing basic survival duties when wearing suit B in the 50 person lifeboat. Discussion There are basically four important findings that have been revealed. First and foremost, both seafaring populations that have been measured are considerably heavier than the IMO standard. Eighty-five percent of people had a body mass greater value than 75 kg. The average for the two populations was 86 and 88 kgs. In two other studies recently conducted at Survival Systems Ltd and Dalhousie University, the reported mean body mass was similar to the values reported in this study. The mean self-reported measure on 351 people was 89 Kg and a mean value directly measured on over 100 subjects was 90 Kg. Although weight is not a good estimator for space allocation, it is an essential measurement for overall weight, stability and impact testing of lifeboats. Therefore, the IMO needs to conduct an international review of basic human anthropometry (weight, height, hips and shoulders) with a view to increasing the current body mass value of 75 Kg. Second, use of hip breadth as a method for allocating seating space is flawed. In our study, the shoulder breadths were all consistently greater than hip breadths. This was clearly demonstrated in the way that none of the seafarers even in their work clothes, could fit their shoulders squarely against the bulkhead, yet their bottoms squashed into the seat pan. IMO should use shoulder breadth as a space allocation tool, not hip breadth. Third, it was shown physically that the 430 mm seat pan allocation is not adequate for the seafarer population and a 95th percentile shoulder breadth of 575 mm should be considered. Fourth, and last, the wearing of an immersion suit does indeed increase the physical size of each seafarer. He or she will require an increase in space allocation. The more important consideration is that the present weight and space allocation requires reevaluation on an international scale. There is a need for a formal anthropometric survey of at least height, weight, hip and shoulder breadths on seafarers from around the world. After this IMO, can revise the current Live Saving Appliance Code to better represent the seafarer population. Based upon the information reported in this study current lifeboat loading needs to be down rated by about 15% in order for people to conduct their survival duties correctly. Conclusions & Recommendations
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1. Eighty-five percent of the seafaring population has a body mass greater than 75 kg. IMO must increase this criterion value but should measure other international seafaring populations prior to standardizing the value. 2. The shoulder breadth measurements were always greater than the hip measurements. Hip measurements are a poor indicator of space allocation. 3. Shoulder breadth measurement should be used for space allocation. However if IMO does not wish to change the basis for the seat pan measurement, then it should be based on the seated hip breadth measurement. This value needs to be substantially increased from 430 mm. The 95th percentile value (uncompressed) for seated hip breadth in work clothes is 466 mm and for the suited condition is 511 mm. 4. Independent of the wearing of an immersion suit, the current lifeboat rating capacity should be downgraded by approximately 15%.
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Research Studies to Investigate the Impact of Immersion Suit Use in an Emergency Situation By: C.J. Brooks1, J.W. Kozey2, S.L. Dewey2, R.C. Brown3, K.A. Howard1, D. Drover4, S. MacKinnon4 and J. McCabe2 1
1
Survival Systems Limited, Dartmouth, Nova Scotia 2 Dalhousie University, Halifax, Nova Scotia 3 Marine Institute, St. John’s, Newfoundland 4 Memorial University, St. John’s, Newfoundland
Introduction
At the 47th session of the Design and Equipment sub-committee of the I.M.O, ( February, 2004), a paper was submitted by China (DE 47/5/6) based upon a Chinese report that wearing an immersion suit will reduce the effective capacity of lifeboats. The Chinese delegation introduced an important topic. In addition to Safety of Life at Sea (SOLAS) requirements, in many parts of the world, nations who operate in cold waters require the carriage of immersion suits to protect their domestic seafarers. There is already evidence that shows that the wearing of personal protective equipment increases anthropometric dimensions and a loss in functional reach. (Carrier & Meunier, 1996; Laubach & Alexander, 1975, Holland, Wilson, & Niven, 1999). More recent work related to the maritime environment conducted jointly by Dalhousie University and Survival Systems Limited on offshore workers by Reilly et al. (2004) has shown that wearing one type of helicopter passenger suit increased the structural dimensions in offshore workers by 13 to 150 mm depending on the particular dimension. Reilly (2003) also reported that when a subject was seated and wearing a helicopter passenger suit, that functional reach above shoulder height was restricted. Furthermore, there is preliminary information to suggest that the effects of wearing the suits will have an effect on the design of lifeboats and in the revision of international standards for space allocation. As recently as 2003, the Erik Raude oilrig in Halifax had the 72 person lifeboat down rated to fit 60 people. However, no one has specifically measured a population of seafarers to record the effect of the addition of immersion suits on space allocation and physical performance in lifeboats. 1.1 Objectives of this work Based upon this past research, Transport Canada has requested additional information on the change in structural dimensions of two groups of seafarers due to wearing an immersion suit. The following human factors research questions were examined using a sample of seafarers: 1.1.1. Measurement of selected anthropometric dimensions of a typical sample of seafarers dressed in work clothing.
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1.1.2. The effect of wearing three typical immersion suits on shoulder and hip breadth in seated and standing postures. 1.1.3. The effect of wearing three typical immersion suits on loading times and safety in two lifeboats. 1.1.4. The effect of wearing three typical immersion suits on the maximum loading capacity of a lifeboat Two separate research studies were conducted, one in Dartmouth, Nova Scotia at Survival Systems Limited and the second in St John’s, Newfoundland at Memorial University and the Marine Institute. The first was approved by the Dalhousie University Ethics Committee, Nova Scotia and the second by the Memorial University Ethics Committee, St. John’s, Newfoundland. 1.2
Study 1 – Structural Anthropometry (Dartmouth and St. John’s):
The hip and shoulder breadths from a sample of 87 seafarers in Dartmouth, Nova Scotia and 84 seafarers in St. John’s, Newfoundland were recorded. Four different conditions were examined in Dartmouth: normal work clothing, and three different immersion suits typically used in offshore Nova Scotia (Figures 1, 2 and 3). Only two conditions were examined in St. John’s: normal work clothing and the immersion suit. Figure 1:
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1.3 Study 2 – Determination of lifeboat capacity and loading (Dartmouth only): A sample of up to 50 ( subjects were used to measure the effects of the addition of the immersion suits on loading times, safety and capacity of two typical lifeboats. These lifeboats were a 50 person lifeboat (Figure 2) and a 36 person lifeboat (Figure 3). The subjects were first boarded wearing their work coveralls (control) and then wearing each of the three different immersion suits on top of the work coverall. Figure 2: Lifeboat A (50 person)
Figure 3: Lifeboat B (36 person)
2 Methods and Procedures The methods and procedures will be presented in sections according to the specific studies. 2.1 Study 1 – Structural Anthropometry (Dartmouth and St. John’s): Overall, height and weight measures were recorded using a standing anthropometer and weigh scale, respectively. Each seafarer’s body mass index (BMI, Kg/m2) was calculated using the height and weight data. Standard structural anthropometric techniques were used to record the hip and shoulder breadth of the sample of 87 subjects in Dartmouth, Nova Scotia and 84 in St. John’s. The seafarers consisted of both males and females. Data provided by Sable Offshore Energy Inc. indicated that of the 87 subjects selected at least 5%, but no more than 15% should be female. All the subjects were recruited from the pool of seafarers who attend the required marine survival training courses at Survival Systems Training Ltd., Dartmouth, Nova Scotia or the Marine Institute, St. John’s, Newfoundland. Each subject was shown a copy of the protocol and signed an informed
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consent form. Shown in Figure 6 is an image of a standing and seated person and the three breadth dimensions taken using the anthropometer. The three dimensions were: A – Standing shoulder breadth, B – Standing hip breadth, and C – Seated hip breadth.
A
B C
Figure 4: Schematic of the three anthropometric dimensions. The original images are from Van Cott and Kinkade (1972). Shown in Figure 5 is the Harpenden anthropometer that has been used in past studies at SSL and a new anthropometer developed specifically for this study. Preliminary data indicated that the breadths to be recorded would exceed the measurement range of the original device; therefore an enlarged version of this device was built to accommodate the wider measures. Second, a force gauge was added to the device to record the amount of compression the experimenter produced on the subject’s suit during the measurements. This force gauge was important in (a) standardizing the measurement, (b) providing practical repeatable measurements to identify a comfortable fit in the seat and (c) to consistently reproduce a very tight fit in the seat. Bi-deltoid (shoulder breadth) and bi-trochanteric (hip breadth) measurements were taken on each subject (a) while wearing their standard work clothes, and, (b) while wearing each of the three different immersion suits worn over the top of their work clothes (this is exactly the condition that would occur in marine abandonment). A marginally different immersion suit was used in Newfoundland. During the suited conditions each measure was first recorded using no compression (maximum breadth) and with a standardized compression of 2700 grams (6 lbs) to represent a very tight fit in the lifeboat.
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Figure 5: Standard Harpenden Anthropometer (above) and new device (below) built for this study. Finally, additional calculations and observations were made on the practical application of the data to the fit of the humans in the normal allotted seat space. This was accomplished by comparing the shoulder and hip breadth of a random sample of the subjects to the linear space allocation 430 millimeters in the IMO Life Saving Appliance Code. A simple mathematical model was developed to calculate the cumulative length of the row of subjects compared to the value used in the standard. The subject’s were modeled as being seated side-by-side just touching each other. The cumulative length was the addition of the breadth measure of each person as one moved along the row. 2.2 Study 2 – Human factors and lifeboat loading trials (Dartmouth): A total of 50 subjects were recruited for participation in the second study. At least 5 of the subjects were female. The subjects were recruited through sign-up sheets posted within Dalhousie University, local shopping plazas and an advertisement through the Federal Department of Human Resources offices. Most importantly, an inclusion criterion was developed to allow for an anthropometric match between the subjects and the seafarers who participated in part 1 of the study.
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Testing was conducted using the two lifeboats at Survival Systems Ltd. (type and A and B). Upon arrival at the site, the subjects were shown to a classroom and received a review of the purpose of the study. Subjects were then asked to sign the document of informed consent and then received a brief safety lecture by SSL personal on lifeboat evacuation and were provided with the opportunity to ask any additional questions about the experiment. Next, the subjects were provided with three immersion suits for their personal use during the experiment. The subjects changed into work dress and were transported to the test area and mustered in the Temporary Safe Refuge (TSR) to begin the experimental trials. Presented in Table 1 is the list of all the conditions used for simulated evacuation. The trials were organized based upon availability of each vessel and the minimal suit changes of the subjects. At the conclusion of each lifeboat loading trials, the subjects were asked questions about the ease or difficulty of entry and exit of the lifeboat, comfort and fit and ease or difficulty of strapping in. After all trials, they completed one final questionnaire. A sample of the questionnaire is provided in Appendix A. Lastly, the subjects were debriefed, paid their subject pay and allowed to leave. Table 1: List of test conditions for the simulated evacuation from TSR to launch positions of two lifeboats. Tria
Condition
Hatche
Lifeboat
Rated capacity
A A A A B A B B B
50 50 50 50 36 50 36 36 36
s 1 2 3 4 5 6 7 8 9
Work clothes - practice Work clothes Immersion suit A Immersion suit B Immersion suit B Immersion suit C Immersion suit C Immersion suit A Work clothes
1 1 1 1 2 1 2 2 2
All trials started at the Temporary Safe Refuge (TSR) and were completed when subjects were safely secured within the lifeboat with doors closed and dogged. 2.2.1 Timing related data collection for lifeboat launches Using standard stopwatches, the following data were recorded. All timing measures were started from the signal to “abandon the vessel”. 2.2.1.1
Initial Response Time: • Time for first and last person to arrive at lifeboat
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2.2.1.2 Load Response Time: • Time for first person to board the lifeboat Time for last person to board the lifeboat • • Time for hatch(es) to be secured Time for first and last person to be seated and buckled into lifeboat • It was anticipated that there would be a very tight fit inside the lifeboat at maximum capacity, therefore not possible to add additional scientific recorders inside. Therefore, two research assistants who simulated two coxswains were placed inside the lifeboat to record the times, make observations of the fit and difficulties if any, which existed during the trials. They were accounted for in the fit. 2.3
Data Analysis
2.3.1 Study 1 – Structural Anthropometry (Dartmouth): The anthropometric data for the Nova Scotia data were collated and standard descriptive statistics (mean, standard deviation, 5th, 50th and 95th percentile values) were calculated using MINITAB. As well, a standard statistical analysis (two (conditions) by four (suits) ANOVA) was used to test for any significant main and interaction effects. Four practical tables were developed for Transport Canada showing the range of heights, weights, shoulder and hip breadths and any significant correlations among them during the various experimental conditions. For the anthropometric data from Newfoundland the standard descriptive statistics were performed, but further analysis using an ANOVA was considered unnecessary and not performed. To compare the datasets, standard t-Tests were performed on each of the main independent variables between the Newfoundland and Nova Scotia data. For all statistical comparisons an alpha level of 0.05 was chosen as the level of significance for the t-test and correlations and for all ANOVA, post-hoc tests. 2.3.2 Study 2 – Human factors and lifeboat loading trials (Dartmouth): All time measures were tabulated and descriptive statistics were developed to describe the times to complete each task and subtask. Notations were made concerning the ease or difficulty with any of the sub-tasks involved in boarding the lifeboats such as strapping in, ease of movement, etc. for all passengers when fully loaded including the two coxswains. No further statistical tests were performed on these data. The questionnaire data were tabulated and frequencies of responses and percent responses were calculated for each trial. The percent responses were plotted and qualitative comparisons of the responses were made to contrast the effects of the lifeboats and suits.
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3
Results
3.1 Study 1 – Structural anthropometry – Survival Systems Limited, Dartmouth The results of the 87 seafarers tested in study 1 are shown in Tables 2 and 3. Table 2 provides a description of age, physical dimensions and marine / offshore experience. There were 80 males and 7 females. This is the correct male / female ratio (10-15:1) expected for offshore marine workers. Their age ranged from 18 to 58 years, their mass ranged from 46.8 to 145.5 kg, height ranged from 1563 to 1913mm, BMI ranged from 17.9 to 45.7, and marine work experience ranged from 0 to 34 years. Table 2: Descriptive statistics for Seafarers at Survival Systems Limited. (n=87) Mean SD Median Min Max Age (yr) 37.1 9.8 36.0 18.0 58.0 Experience (yr) 6.4 8.1 3.0 0.0 34.0 Mass (Kg) 86.3 15.5 85.5 46.8 145.5 Height (mm) 1748 71.7 1750 1563 1913 2 BMI (Kg/m ) 28.2 4.4 28.1 17.9 45.7 Table 3 shows the mean and standard deviation of the physical dimensions for shoulder breadth, hip breadth (standing) and hip breadth (seated) in work clothes (control), and wearing the three different survival suits in the comfortable fit and the compressed fit condition. Table 3: Descriptive statistics for the Seafarers at hip and shoulder dimensions for different conditions at Survival Systems Limited. (n=87) Dimension Condition Work clothes Suit A Suit B Suit C Mean SD Mean SD Mean SD Mean SD Normal 515 38 604 38 604 38 595 31 Shoulder breadth Comp. 441 35 472 36 472 36 468 39 Normal 383 26 427 31 427 31 425 29 Hip breadth standing Comp. 322 23 330 23 330 23 335 26 Normal 419 29 452 23 452 23 459 29 Hip breadth seated Comp. 357 28 377 29 377 29 380 29
3.1.1 Overall effects The statistical analysis for this study examined two main effects, which were; (1) the wearing of work clothes versus immersion suits and (2) the effects of no compression versus compression on the shoulder and hip breadth measures. In addition, further comparisons were made of the combination of the effects of suits and compression (interaction effects) on these measures. Overall there were significant main effects of suits and condition (compression and no compression) and a significant interaction of suits by conditions. The shoulder breadth, hip breadth standing and hip breadth seated dimensions recorded in the work clothes were significantly smaller than the same dimensions for any the suit conditions (F=361.5, df 3,603, p
