We occasionally get questions from customers confused about the buoyancy ratings for life vests.
How can a personal flotation device (PFD) rated at 15.5 lbs, hold up a person of 200 lbs?
While the rating method may seem confusing at first glance, we will explain the math behind it. But first we have a quick guide to understanding the current US Coast Guard regulations on various PFD types and their ratings.
PFD Types
Type I – Offshore Life Jacket. Designed for extended survival in rough, open or remote water. It has the highest float rating and usually will turn an unconscious person face up. Minimum buoyancy rating 22 lbs. adults, 11 lbs child, 7 lbs infant.
Type II – Near Shore Buoyant Vest. Best use for adults and children in calm inland water where there is chance of fast rescue. Slighly less bulky than Type I vests, and can turn some unconscious people face-up. Minimum buoyancy 15.5 lbs. adults, 11 lbs child, 7 lbs infant.
Type III – Flotation Aid: For use in calm water by conscious users, where there is good chance of fast rescue. Type III is generally the “paddler’s choice” because they are designed for general boating/water activities as makred on the vest, and are more comfortable. Minimum buoyancy 15.5 lbs. adults, 11 lbs child, 7 lbs infant.
Type IV – Throwable Device: Boat cushions, rings, and horseshoe buoys. These are for use in calm water where there is good chance of fast rescue. They are not designed to be worn and should be supplemented with a wearable PFD. Varying minimum buoyancy 16.5 to 18 lbs dependent on device.
Type V – Special Use Device. “Special Use” PFDs include commercial whitewater rafting vests, work vests, deck suits, and hybrid inflatables with restricted use for specific activities as outlined on the vest – be sure to READ the USCG instructions sewn or printed on the device. Varying minimum buoyancy 15 to 22 lbs dependent on device.
Inflatable PFDs: These rely on inflatable chambers that provide buoyancy when inflated by a C02 cylinder. Uninflated, they are less bulky than foam jackets. Please note: these must be regularly inspected and re-armed. Not for non-swimmers or for long hours in rough water. While some are automatic, most of these must be physically inflated, meaning, you need to be cognizant to orally inflate, or pull the inflation cord. Manual inflatable PFDs are not a great choice for situations when you might be hit by something. Varying minimum buoyancy 22 to 33 lbs inflated dependent on device.
How Do We Calculate Weight in Water?
Approximately 80% of the human body is water, thus will not weigh you down (has no weight) in water. Additionally, bodies on average have 15% fat, which is lighter than