Buoyancy aid
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Buoyancy aids are a specialist form of personal flotation device (PFD) used most commonly by kayakers and canoeists. They are designed as a flotation aid, rather than a life-saving device and have several key differences to other PFD's and life-jackets.
Canoeing and kayaking buoyancy aids are designed with mobility in mind. A buoyancy aid that doesn't fit properly can restrict a paddler's (kayaker's) range of movement, which could cause them to tire or prevent them from paddling properly. They typically have front and back foam buoyancy, with none or very little around the sides to allow for better arm movements.
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[edit] Types of buoyancy aid
All canoeing/kayaking buoyancy aids are made with a foam core, instead of being inflatable like some life jackets. This removes the possibility of them bursting or not being activated in the case of an incapacitated paddler. The foam used is typically closed cell PVC (polyvinyl chloride), although some manufacturers are now starting to use less toxic and more recyclable materials. Older designs used vertically aligned ribs of foam all around the body, but more modern designs typically feature front and rear slabs of foam buoyancy, with the sides left clear to allow unrestricted rotation and arm movement. Most buoyancy aids are one of three basic designs:
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- Over the head vest, where the one-piece vest is pulled on over the head.
- Front zip jacket, where the buoyancy aid is worn like a regular jacket, zipped up at the front. This design limits the front-buoyancy as it requires two separate blocks of foam and a gap for the zip.
- Side zip is a combination of the other two, with a zip on the side rather than along the front. The added gap in one side makes it easier to get the vest on, and means that the front buoyancy can be one whole piece.
All buoyancy aids include some form of strap for tightening the buoyancy aid, preventing it from coming off in the water. Many white water designs feature multiple straps on the shoulders and waist to ensure the buoyancy aid can not be swept off in fast water. They may also include pockets for storing equipment and a range of safety and rescue features. Some lower quality ones only offer a belt, and these are often poor fitting and may be designed for generic water sports rather than specifically canoeing/kayaking.
There is a large variety of designs to fit every figure and purpose. It is important to have a buoyancy aid that fits comfortably, allowing freedom of movement. It is also important that it is suitable for the chosen discipline and the grade of water being paddled. Each discipline has different requirements and although one buoyancy aid can be used for multiple disciplines, there are several factors to consider which type to choose.
[edit] Canoe polo and slalom
These are designed with high maneuverability as a key feature, often at the expense of buoyancy. Minimalistic designs which tend to hug the body tightly and are well cut around the arms aim to allow the wearer complete freedom of motion (something important to both Slalom and Polo paddlers as well as playboaters). These vests may not be fully suitable for other purposes, such as whitewater paddling where additional buoyancy is required due to the higher flow of water.
[edit] Sea and touring
Buoyancy aids for sea and long distance touring often feature several large pockets for storing essential equipment, and many also accommodate hydration packs. They have to be comfortable to wear whilst paddling for long distances, and so typically have very low cut sides to allow the arms free movement. More recently they are being designed more and more like whitewater vests, with low cut fronts to allow the paddler to lean forward easily.
[edit] Whitewater
Whitewater buoyancy aids are designed to provide enough buoyancy in fast whitewater rivers, should the paddler capsize and leave the kayak. They are often more bulky than Slalom/Polo vests, but are usually cut short at the front to allow the paddler to lean further forward despite the thicker foam and allow good trunk rotation for quick turns. They always have shoulder and side straps to ensure they are not swept off in fast rapids.
They typically feature one or two pockets to store basic essentials such as a rescue knife, carabiner and tow-line. Many often also feature harnesses for use in rescues, however these are often used without proper training and can become more of a danger to both the rescuer and the swimmer if used incorrectly.
[edit] Specifications
Buoyancy aids come with a set of specifications detailing their sizing, weight range, and the standards they adhere to. This is often in a table printed onto the inside of the buoyancy aid, or a label on the bag/box. Most companies give the specifications for each of their models on all of their buoyancy aids, to simplify the manufacturing process, so it is important to check the model and size range of your particular buoyancy aid.
Buoyancy aids should detail:
- Chest size: Usually a range either in inches or centimetres.
- Weight range: Either in kilograms or pounds.
- Force provided: The buoyant force provided by the buoyancy aid.
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- For a buoyancy aid to be sold in the European Union, it must be C.E. tested and approved. Canoe and kayak buoyancy aids are usually "50 newton class" flotation aids (CE code 393), which means they will provide a minimum of 50 N (newtons) of buoyant force to a swimmer. Some buoyancy aids class as "100 N", these provide more force, enough to flip a swimmer over onto their back, and must include a neck support. These are usually used for children or for inexperienced raft crews on white water.
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- In the USA, a buoyancy aid may be approved by the United States Coast Guard (although this is not a requirement). Most canoeing and kayaking buoyancy aids class as "Type III Flotation Aids", which means they provide a minimum of 15.5 lbf (pounds-force) (69 N) of buoyancy.
[edit] Ageing
The foam used in buoyancy aids does degrade with age. Manufacturers add additional foam to ensure that their buoyancy aids will still provide enough force even after years of use. A rough life expectancy is three years of use, although buoyancy aids exposed to polluted water may degrade faster than normally expected.
[edit] Harnesses
Many white water buoyancy aids, as well as some sea kayak ones, feature a safety harness. These fit around the buoyancy aid below the arms and can be used for Live Bait Rescues (where a rescuer swims out into the river on a line to rescue a swimmer) or for anchoring a belayer onto the bank. They feature quick-release buckles to quickly remove the harness, and these are often (but not always) designed to release automatically past a certain load/pressure. Often harnesses have a metal ring at the back for attaching a rope with a screwgate carabiner. Use of a non-locking carabiner can allow the carabiner to accidentally clip onto other straps on the buoyancy aid during use, thus preventing the harness from being released, and as such they should not be used for attaching to a harness.
Many harnesses feature a metal friction plate which stops the belt from slipping under high-load situations, however these can also prevent the harness coming off when swimming and as such present more of a hazard than an aid. It is often recommended that the belt be removed from within the friction plate and only threaded back through if the situation requires an anchored belay.
Improvised harnesses (ropes around the waist, belts, or attaching ropes directly onto the buoyancy aid itself) can present a serious danger to the wearer, as they can not be released or may not be strong enough to withstand the load required.
[edit] History
Ancient instances of the life jacket can be traced back to simple blocks of wood or cork used by Norwegian seamen. The modern life jacket is generally credited to one Captain Ward, a Royal National Lifeboat Institution inspector in the United Kingdom, who, in 1854, created a cork vest to be worn by lifeboat crews for both weather protection and buoyancy.
