António Simões Ré

Reduction in predicted survival times in cold water due to wind and waves.

Recent marine accidents have called into question the level of protection provided by immersion suits in real (harsh) life situations. Two immersion suit studies, one dry and the other with 500 mL of water underneath the suit, were conducted in cold water with 10-12 males in each to test body heat loss under three environmental conditions: calm, as mandated for immersion suit certification, and two combinations of wind plus waves to simulate conditions typically found offshore. In both studies mean skin heat loss was higher in wind and waves vs. calm; deep body temperature and oxygen consumption were not different. Mean survival time predictions exceeded 36 h for all conditions in the first study but were markedly less in the second in both calm and wind and waves. Immersion suit protection and consequential predicted survival times under realistic environmental conditions and with leakage are reduced relative to calm conditions.

Correction factors for assessing immersion suits under harsh conditions

Many immersion suit standards require testing of thermal protective properties in calm, circulating water while these suits are typically used in harsher environments where they often underperform. Yet it can be expensive and logistically challenging to test immersion suits in realistic conditions. The goal of this work was to develop a set of correction factors that would allow suits to be tested in calm water yet ensure they will offer sufficient protection in harsher conditions. Two immersion studies, one dry and the other with 500 mL of water within the suit, were conducted in wind and waves to measure the change in suit insulation. In both studies, wind and waves resulted in a significantly lower immersed insulation value compared to calm water. The minimum required thermal insulation for maintaining heat balance can be calculated for a given mean skin temperature, metabolic heat production, and water temperature. Combining the physiological limits of sustainable cold water immersion and actual suit insulation, correction factors can be deduced for harsh conditions compared to calm. The minimum in-situ suit insulation to maintain thermal balance is 1.553-0.0624·TW + 0.00018·TW(2) for a dry calm condition. Multiplicative correction factors to the above equation are 1.37, 1.25, and 1.72 for wind + waves, 500 mL suit wetness, and both combined, respectively. Calm water certification tests of suit insulation should meet or exceed the minimum in-situ requirements to maintain thermal balance, and correction factors should be applied for a more realistic determination of minimum insulation for harsh conditions.

Probabilistic Analysis of Local Ice Loads on a Lifeboat Measured in Full-Scale Field Trials

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team at PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRC

Evacuation in Ice: Ice Loads on a Lifeboat During Field Trials

Full-scale field trials of a conventional lifeboat in pack ice have yielded insights into the design and operation of evacuation craft in ice. The multi-year trials program used an instrumented lifeboat to investigate design considerations such as powering and propulsion, hull form, maneuvering, ice loads and ergonomics. Operational issues that have been examined include ice management for emergency evacuation, coxswain competence and training. This paper focuses on local ice loads measured on the hull during aggressive operations in pack ice. Field measurements are presented and the implications for design and safe operations are discussed.Copyright

Comparison of thermal manikins to human thermoregulatory responses

Immersion suits are lifesaving appliances (LSA) designed to protect the wearer if they become accidently immersed in cold water by reducing the cold shock response and delaying the onset of hypothermia. Immersion suits are certified to both national and international standards; some of which require the thermal protective properties to be tested using humans or thermal manikins. The ethical nature of testing with humans has been questioned [1] due to the physically grueling nature of these tests, thus testing with manikins may be preferential. However, previous work has shown that discrepancies exist between thermal manikins and humans that could result in immersion suit selection that would benefit the former more than the latter who would ultimately use it [2]. This study investigated the thermoregulatory responses of humans and compared them to a thermal manikin while wearing immersion ensembles with insulation distributed in various configurations hypothesized to be beneficial to humans and manikins.

Assessment of life saving appliances regulatory requirements — Human factors knowledge gaps

Life saving appliances are used throughout Canada and around the world every day by a large number of individuals who work or travel over open water. Personnel rely on these life saving appliances to help provide protection from harsh environments, and reduce the risk of injury or death in the event of a marine accident. Due to their importance in helping to save lives at sea, life saving appliances are built and tested according to specific standards and regulations to ensure that they provide the level of performance required. Unfortunately, life saving appliances do not always perform as expected which can lead to unexpected injuries or loss of life. Given that life saving appliances must meet specific performance goals as prescribed by standards and regulations, it is often these goals that fall short of what is actually needed during a marine accident. A knowledge gap is created when the testing conditions, as outlined in a standard or regulation, do not accurately reflect those conditions found during a marine accident. As a result, a life saving appliance will often meet performance goals that are below those required to prevent an injury or loss of life during an actual marine accident. The Canadian regulation: “Life Saving Equipment Regulations” C.R.C., c. 1436 was reviewed and possible knowledge gaps with respect to human factors were identified. The goals and requirements for life saving appliances in the regulation were compared against existing work done in the area of marine safety to determine if what was prescribed adequately reflected what could be found during a marine accident. There were many gaps identified in the regulation, commonly caused by prescriptive wording specifying conditions not commonly found during a marine accident. These knowledge gaps will widen as conditions become more severe than what is prescribed in the regulations possibly leading to even further decrease in life saving appliance performance than what is already measured.