Buoyancy ratings
Lifejackets and buoyancy aids are rated in newtons (N) of buoyancy:
| Rating | What it's for |
|---|---|
| 50N | A buoyancy aid, not a lifejacket. Helps a conscious swimmer stay afloat close to help, as in dinghy sailing. It won't turn you face up. |
| 100N | For sheltered and calm waters, where help is close. May not turn an unconscious person face up in rough water or in heavy clothing. |
| 150N | The usual choice for yacht sailing. Designed to turn an unconscious person face up in most conditions. |
| 275N | For offshore and extreme conditions, or when wearing heavy clothing or carrying tools that trap air or add weight. |
Automatic or manual?
- Automatic lifejackets inflate on their own when they're immersed in water. They're the usual choice on yachts, because they work even if you're knocked unconscious going overboard.
- Manual lifejackets inflate only when you pull the toggle. They suit situations where you might be splashed or briefly in the water and don't want them to go off, but they rely on you being conscious and able to pull it.
Both types also have a tube to top up the buoyancy by mouth.
The extras that matter
- Crotch or thigh straps: stop the lifejacket riding up over your head when it inflates. Always fasten them.
- Spray hood: covers your face and stops waves and spray being breathed in. It can make the difference in rough water.
- Light: makes you visible at night.
- Harness ring: lets you clip on a tether to the boat's jacklines.
- Beacon: an AIS or PLB beacon fitted to the lifejacket. See EPIRB vs PLB vs AIS beacon.
Fitting and checking
- Adjust it so it's snug over the clothes you'll actually wear, with the crotch straps done up.
- Before each trip, check the gas cylinder is screwed in tight and not used, and that the indicators on the automatic mechanism show it's ready.
- Have it serviced as the manufacturer recommends, typically every year, and replace parts that are out of date.
- Every so often, inflate it by mouth and leave it overnight to check it holds air.