Lifejacket Research

Safety Report by Dr Ross Denton

Researching Lifejackets has exposed quite a few myths and misunderstandings and the subject is not helped when different countries use different labels and specifications for similar lifejackets.  So I will start not by discussing these problems but with a clear recommendation as to what is "Best for Purpose" for our sport of Jet boating.  Most of you recreational boaters will already have a Type 402 Personal flotation device (PFD); please note that these must always have a collar.  PROVIDING you add a $10 crotch strap then you already have the most suitable lifejacket available for recreational boating.  River-racers already have mandatory crotch straps and"Best for Purpose" jackets need to meet the 406 specialised PFD standards previously known as 408.  The photos with this article are the easiest way to explain just what 402, 406 and 408 mean or viewing http://www.maritimenz.govt.nz/Recreational-Boating/Lifejackets/Types-of-lifejacket-and-PFD.asp, which will set out adequate further detail if required.

Fitting crotch straps to all your lifejackets is indisputably the simplest and cheapest way by which you can greatly improve your safety and that of your passengers.  Because gravity usually holds jackets comfortably around our body they feel well fitting, but if you are tipped into the water everything is reversed.  Your arms drop to the bottom of the armholes and the jacket wants to ride up around your ears.  I know of cases where people have slid out of their ill-fitting PFD and deaths have occurred.  Some of you may be unaware that it is already mandatory for all Child Small and Child Extra Small lifejackets to have crotch straps (that’s up to 25kg) and that crotch straps are also mandatory for some offshore yacht races.  The evidence for their value is quite clear.

You may note that I use the PFD and lifejacket terminology interchangeably in this article.  At one time it was argued that only the open seas 401 could be called a lifejacket, with everything else a PFD.  Certainly this large bulky foam 401 is the only jacket I would want if exiting the Wahine or Titanic in open seas, since its design and 100 newtons of lift is guaranteed to support you for extended periods in rough seas and even if you become unconscious.  Industry and legislators now accept the terms lifejacket and PFD will continue to be used interchangeably.  Whichever term you prefer, the characteristic you are looking for in your lifejacket and clothing combined is to maximize the buoyancy around your chest and minimize it around your legs.  The aim is to be vertical and upright in the water, with a second consideration to have more buoyancy on your chest than your back such that there is no tendency to tip forwards.

To better understand the next section you need to understand the Industries “Roll over test”.  This is an accepted test for all PFD’s performance and is conducted in a fresh water pool.  After swimming a few strokes to get flat on their tummy the lifejacket wearer brings their arms close to their side and goes as limp and floppy as they can, this mimics an unconscious person as far as possible, and a jacket which repeatedly rolls them onto their back with face above water passes.  Now if you read your 402 jacket label it can be somewhat unnerving to find they must be marked "May not be suitable for all conditions" and indeed this reflects that they cannot be 100% guaranteed to support every unconscious person in every situation.  I spoke at length with Bernard Orme about this.  Not only is Bernard the Operations Manager for Hutchwilco but he was also a member of the most recent NZ Standards Committee for lifejackets and also the Australian Standards committee.  Based on this conversation you can be reassured the 402 will actually work in the VAST majority of cases even if you were unconscious, but with the recommendation that you also have crotch straps because of the tendency for lifejackets, including the 402, to ride up on the wearer.  One of the rare examples of failure they found was with air trapping in particular types of trousers such that leg position prevented rollover.  Be reassured the failures are rare and only in unusual circumstances.

Let’s briefly and for completeness cover and dismiss Buoyancy Vests and Ski-Vests 403/404/405 as almost everything without collars should not be considered as “Best for Purpose”.  Inflatable jackets are also not considered as ”Best for purpose” for jet boating since their disadvantages outweigh their advantages.  Alistair Thomson, a Maritime officer and member of the National Pleasure Boat Safety Forum with Maritime New Zealand listed four reasons that make inflatables less than ideal for jet boating use; these are impact protection, thermal, servicing and deployment delay.  Impact protection, which is sometimes rather important in jet boating, is not just a matter of having that nice foam barrier right around your chest, it’s also that the inflatable being a sausage shape would tend to concentrate any impact at one point on the ribs increasing the injury risk.  A well-fitting jacket forms one more reliable layer for wind and rain protection.  Inflatables only operate successfully if the CO2 canister is engaged firmly with no rust on the join and the units will need regular servicing.  Failures are known and considering the hassle factor to keep fire extinguishers certified, I personally wonder why anyone would want that extra servicing hassle?  Finally, the accepted design specifications mean it can be 5 seconds before an inflatable jacket actually has inflated and this significant time delay increases, for example, your risk of being snagged on underwater objects.  JBNZ policy is to not recommend inflatables.

Time and again in researching this PFD column, I was made aware that the design of lifejackets has become something of a compromise.  Overcoming those macho reactions and making jackets that people would accept as comfortable and actually wear has competed with the need for ultra-reliability.  Surprisingly, market research even ruled out routinely adding crotch straps because this made PFD’s even less acceptable to many macho male.  JBNZ can be proud of its longstanding stance which requires the use of lifejackets with a collar at all times.  Clear evidence suggests it is time to include a recommendation to add and use crotch straps at all times.