Wearalifejacket.com (part of the Cook-Rees Memorial Fund) has a basic list of references and publications related to lifejackets here

http://www.wearalifejacket.com/walcEn/home01En.html

This is a bit dated (about 2009), but a good summary of where this lifejacket standard harmonization process came from.  This made up the introduction to our SAR-NIF proposal that we attempted to get funded in 2010 and 2011.  Thet SAR-NIF project was a 2 year program to investigate how flotation devices work in non-calm conditions and how to predict the performance of a floatation device.  Nearly all of the current knowledge about floatation device performance is related to still water.  Unfortunately, our initial testing indicates that still water measurements don’t have much predictive power for realistic performance expectations.  This post will give the background…Future posts will update you with the current status of this process

A report prepared by the Canadian Red Cross in 2006 indicated that between 1991-2000, there were 4,671 water activity related drownings in Canada (Canadian Red Cross, 2006). Of these, 1,803 (39%) were directly related to boating activities (Canadian Red Cross, 2006). The SMARTRISK-Will it Float? report (2003) prepared for the Canadian Safe Boating Council showed that there is an average of 140 drowning deaths related to recreational boating in Canada each year, but that this might underestimate the actual drowning deaths by up to 43%. Of boating related drownings that occurred in Canada between 1991-2000, 1362 were recreational boating related, 187 were related to daily living activities, and 201 were occupational (Canadian Red Cross, 2006). Although PFD’s are also worn around swimming pools and as an occupational requirement, voluntary PFD wear and use for adults is predominantly a recreational boating issue. The 2005 drowning statistics for the United States indicated that there were 491 boating related drownings, and that 46% of those drownings occurred from small boats (5m or less) (USCG, 2005).

In Canada, standards, regulations, and educational efforts have led to a reduction in the drowning rate to 1.4/100,000 (Canadian Red Cross, 2006). A major obstacle that must be overcome to further reduce drowning deaths is to increase PFD “wearability” and usage. Usage of PFD’s has long been an issue that has been tackled with educational awareness campaigns and regulatory enforcement and substantial effort is put into boater education annually across North America to promote the importance of wearing a PFD. Despite educational efforts to increase PFD usage, wearability of flotation devices is still considered poor. Between 1996-2000, only 11% of recreational boating drowning victims were properly wearing a PFD (Canadian Red Cross, 2006) and the usage rates of PFD’s in Canada remain between 21-47% (Groff & Ghadiali, 2003) with similarl low rates observed in the US (25% for adults) (Quan et al., 1998).

Surveys have shown that the common barriers to PFD usage are complaints of thermal and physical discomfort, donning difficulty, bulkiness, restriction of movement, poor fashion, and a perceived low risk of drowning (Groff & Ghadiali, 2003), which are all wearability issues. In a random survey of Canadian boaters, 74% of respondents indicated that they would be more likely to wear PFD’s if they were: more comfortable, easier to fasten and less bulky (Groff & Ghadiali, 2003). Those types of changes to PFD design require a testing and performance standard with the flexibility to include and evaluate the performance¹ of innovative and more wearable flotation devices. Current PFD and lifejacket standards are prescriptive and are resistant (i.e. limit ability to approve) to innovative flotation devices that are more precise and specific to the requirements of individual activities.

Canadian drowning statistics also show that in 1999, 25% of recreational boating drownings occurred in water conditions classified as rough, 9% in choppy conditions, and 14% in calm conditions (49% unknown water conditions) (Canadian Red Cross, 2006). These statistics show that at least 34% of drownings in Canada occur in water conditions other than calm. Similarly in 2005, 34% of recreational boating related drownings in Canada were related to rough water and high winds (Canadian Red Cross, 2005). Therefore, it is in the best interest for the safety of recreational boaters and PFD users that flotation device performance in waves be better understood and become part of the performance testing process for these devices. Airway protection in waves is critical to survival during immersion because it has been estimated that as few as forty one, 1.5 sec immersions could cause sufficient water inhalation to lead to drowning (Higgenbottam & Slater, 1990?)

Since 1999, the USCG has been working on a PFD reclassification initiative to replace their current five-class system, based on buoyancy and style with a risk-based compliance model (RBM) (Ayyub & Nejaim, 2003). With a RBM, PFD performance would be scored by calculating a weighted sum of PFD performance parameter measurements. If the PFD performance score meets or exceeds the minimum threshold scores for the individual parameters and the overall performance, the device will meet the requirements of the standard. An RBM permits more flexibility in the design of devices, and allows devices with more varied performance and feature combinations to become approved PFD’s.

The current USCG RBM initiative is a continuation of the Life Saving Index (LSI) work proposed by the USCG in 1978 (Wyle Laboratories, 1978). The LSI was intended to provide a normalized method to compare a diverse range of PFD designs on a common scale and evaluate the overall life-saving capability of PFD’s. The principal intention of the LSI was to foster and permit the development of innovative PFD designs by industry, and to permit trade-offs between reliability, wearability, accessibility, and effectiveness of the flotation device (Wyle Laboratories, 1978). These are exactly the same reasons for the development of the current RBM.

An RBM is an approach to flotation performance that deviates from the traditional methods used to evaluate the performance of flotation devices. According to current Canadian (Canadian General Standards Board, 1988) and International Standards (ISO, 2005), human subjects wearing swimming attire don the flotation devices and enter a calm pool where static measurements of the flotation position and turning ability are measured. There are some indications that still water measurements of static flotation position do not correlate well with resultant airway immersions in waves (Sweeney & Potter, 2009). Without a clear understanding of the relationships between various measurements and resultant performance, it is very difficult to select prediction parameters and weighting factors, or to generate prediction equations to relate measurements with performance.

The RBM assesses the probability that a flotation device will be successful at aiding survival during a marine event (Ayyub & Nejaim, 2003). The basic formula used to determine the success probability is shown in Equation 1.

Equation 1

Performance Success Probability=P(AV) ? P(D) ? P(R) ? P(EFF)

where:

• P(AV)-Probability that the device is available (Regulated to be present)

• P(D)-Probability that the device will be donned (improving wearability improves the probability that the device will be worn)

• P(R)-Probability that the device is reliable (probability that the device will not suffer construction failure)

• P(EFF)-Probability that the device is effective at assisting with survival (weighted sum of performance predictors)

P(EFF) is the probability term that addresses the in-water performance of the flotation device. To assess and predict flotation device performance, it is necessary to know which measurements provide the best prediction strength. Rather than establishing a single acceptable minimum criterion for each parameter, a range of values with a minimum threshold is established. A regression equation is developed for the range of values so that the contribution of that parameter to the final estimate of device effectiveness can be calculated. By using this procedure for each of the performance predictors, the probability that a flotation device will be effective is calculated.

The RBM is a departure from the traditional measurement approach and it is also intended to assess the likelihood that a flotation device will be effective in more realistic conditions than still water. The RBM is an exciting prospect for integration into flotation device standards because it permits and promotes the innovation and design flexibility required to improve wearability of flotation devices. From an innovation standpoint, the same effectiveness probability could be achieved by different combinations of the predictor parameters. Therefore, two flotation devices may be designed for different purposes or activities and have different scores for individual parameters, but have the same overall effectiveness probability and be approved. This is called an aggregate score approach. The ability to create flotation devices through a trade-off and aggregate score approach introduces a much greater ability for design flexibility and specificity.

Improving the ability to design innovative flotation devices and providing an option for approval with effectiveness evaluated in relation to performance in waves has the potential to be the most important change that has occurred in flotation device standardization since the introduction of inflatable technology to the recreational market. The ability to improve wearability of flotation devices has the potential to significantly increase the wear rate of flotation devices and reduce drownings.

The current limitation to the RBM is that there is a lack of data available to develop and validate the model (Ayyub, 2007). The selection of prediction parameters, the regression equations for each parameter, the threshold ranges and minimum values, and the weighting (predictor strength) of each parameter are based on expert opinion rather than empirical data. Very few studies (Girton & Wehr, 1984; Hart, 1988; Higgenbottam & Berry, 1989; Higgenbottam & Slater, 1990?; Sweeney & Potter, 2009) have been conducted in this area, in large part because of the lack of suitable wave tank facilities.

As part of the North American Standard for Wearable Flotation Devices, the new RBM will be able to be used to approve innovative flotation devices. There must be strong scientific support and validation behind the RBM before it is used to approve flotation devices for sale to ensure that products will perform as required and as predicted.

Completion of this proposed research program will address many of the unknown aspects of flotation device performance and will contribute to the understanding of the influence that the various performance parameters that have on defining flotation performance in waves. This information is critical to ensure that the RBM develops into a well-founded, model that results in reliable and defendable performance predictions. Also associated with this research is the development of measurement systems and technologies that will permit measurement of flotation device performance and subject motion data during wave exposures. With the objective of predicting the effectiveness of PFD’s in non-calm conditions, it is necessary to capture dynamic measurements in addition to still water measurements in order to explain, understand, and predict flotation device performance. Since dynamic measurements of airway freeboard and torso angle have never been captured during wave exposures, the development and implementation of some new measurement technologies and techniques is required.

Developing and understanding the contributions of the PFD and Lifejacket performance parameters to the prevention of airway immersions will promote the development of a strong, sound RBM for the evaluation of PFD’s and lifejacket of both standard as well as innovative approaches and designs. The purpose of the RBM is to promote wearability, and thus usage, of PFD’s and Lifejackets by providing an avenue for innovative and activity specific flotation products to become approved for use. The RBM will make this possible by providing a normalized evaluation process for all flotation devices that is based on performance and protection of the airways from submersions in waves.

On September 6, 2007, Transport Canada and USCG met in Burlington, Vermont during the annual convention of the National Association of State Boating Law Administrators (NASBLA) and agreed to jointly support the development of a single/common Lifejacket (PFD) Standard in North America. Therefore, both Canada and the United States have responsibilities to contribute to the development of this new standard. In November 2008, Transport Canada struck a working group under the Canadian Marine Advisory Council (CMAC) (Transport Canada, 2009) to focus on the North American Standard for Lifejackets, which includes an implementation of the RBM. This CMAC working group includes representatives from industry, government, and end-users, and provides a forum for discussion and involvement from Canadian stakeholders in the development and implementation of a North American standard for Wearable flotation devices.