2 min read · Updated 26 June 2026
A lifejacket and a buoyancy aid are not the same thing. The difference matters: a lifejacket is designed to turn an unconscious wearer face-up and keep the airway clear; a buoyancy aid only helps a conscious swimmer stay afloat. Choosing the right one — and actually wearing it — is one of the most important safety decisions a sailor makes.
The key difference
- A lifejacket provides high buoyancy and is built to right an unconscious person, floating them face-up so they can breathe. It is for serious conditions and for anyone who might not be able to help themselves.
- A buoyancy aid provides less buoyancy and is a flotation aid only. It keeps a conscious, capable swimmer afloat and gives freedom of movement, but will not turn an unconscious wearer face-up.
How they are rated in Australia
In Australia, flotation is graded by buoyancy in newtons under the standard AS 4758. The main levels are:
- Level 50 / 50S — buoyancy aids: a flotation aid for conscious swimmers, favoured by dinghy racers for freedom of movement, suited to sheltered water close to help.
- Level 100 — a general-purpose lifejacket for calmer, more protected waters.
- Level 150 — a general-purpose lifejacket for most offshore and coastal use.
- Level 275 — a high-buoyancy lifejacket for offshore and extreme conditions, or when heavy clothing or gear is worn.
Higher numbers mean more buoyancy. (The exact carriage and wear rules vary by state and vessel — always check your local maritime authority.)
Foam vs inflatable
Lifejackets come in two constructions:
- Foam (inherently buoyant) — floats because of the buoyant material built in. It works instantly, needs little maintenance, but is bulkier.
- Inflatable — slim and comfortable until it inflates from a gas cylinder, either automatically on contact with water or via a manual toggle. High buoyancy in a compact package, but it must be serviced regularly so the cylinder and firing mechanism are reliable.
Which should you wear?
Match it to the sailing:
- Active dinghy racing, sheltered water, strong swimmer, help close → a Level 50 buoyancy aid.
- Keelboats, yachts, offshore, rough or cold conditions, non-swimmers → a full lifejacket (Level 100, 150 or 275) that will turn you face-up.
Whatever you choose, it only works if you wear it and keep it in good order — an unworn or unserviced jacket saves no one. Flotation is a core part of man overboard recovery and of the wider offshore safety equipment. For the vocabulary, see the sailing terms glossary.
Frequently asked questions
- What is the difference between a lifejacket and a buoyancy aid?
- A lifejacket is designed to turn an unconscious person face-up in the water and keep their airway clear, providing high buoyancy for serious conditions. A buoyancy aid provides less buoyancy and is a flotation aid only — it helps a conscious swimmer stay afloat and gives freedom of movement, but will not turn an unconscious wearer face-up. Lifejackets are for safety in worse conditions; buoyancy aids suit active dinghy sailing in sheltered water where help is close.
- How are lifejackets rated in Australia?
- In Australia lifejackets are classified by buoyancy in newtons under the standard AS 4758. The main levels are Level 50 (and 50S) buoyancy aids, and Level 100, 150 and 275 lifejackets. Higher numbers mean more buoyancy: a Level 50 is a flotation aid, Level 100 and 150 are general-purpose lifejackets, and Level 275 is a high-buoyancy jacket for offshore and extreme conditions or when heavy gear is worn.
- What does Level 50 mean on a lifejacket?
- A Level 50 (or 50S) is a buoyancy aid providing 50 newtons of flotation. It helps a conscious wearer who can swim stay afloat and allows freedom of movement, which is why dinghy and small-boat racers favour it. It is not designed to turn an unconscious person face-up, so it is suited to sheltered water close to help rather than offshore or rough conditions where a full lifejacket is needed.
- What is the difference between inflatable and foam lifejackets?
- A foam (inherently buoyant) lifejacket floats because of the buoyant material built into it — it works instantly and needs little maintenance, but is bulkier. An inflatable lifejacket is slim and comfortable to wear until it inflates from a gas cylinder, either automatically on contact with water or by pulling a manual toggle. Inflatables give high buoyancy in a compact package but must be serviced regularly to make sure the cylinder and firing mechanism work.
- Which should I wear, a lifejacket or a buoyancy aid?
- Match it to the sailing. For active dinghy and small-boat racing in sheltered water where you can swim and help is close, a Level 50 buoyancy aid gives the freedom of movement you need. For keelboats, yachts, offshore sailing, rough or cold conditions, or non-swimmers, a full lifejacket (Level 100, 150 or 275) that will turn you face-up is the safer choice. Whatever you choose, it only works if you actually wear it and it is in good order.