Lifejacket & Buoyancy Aid Basics

Guide to Buying a Buoyancy Aid or a Lifejacket

Buoyancy aids are ideal for watersports where a bulky lifejacket would get in the way, while lifejackets are commonly worn in more offshore conditions, but what’s the difference between a buoyancy aid and a lifejacket, and what type of buoyancy aid is right for you?

The term ‘buoyancy aid’ generally refers to a 50N flotation device. This is compared to a lifejacket, which would normally have a rating of 100N or 150N. These terms refer to the buoyancy in Newtons, but this calculation is not absolute, and is relative to the size of the wearer, so for example a 150N child lifejacket will normally have less buoyancy than a 150N adult lifejacket. The term lifejacket also generally means that the product has its flotation arranged in such a way as to turn the wearer in to a face up position in the water, allowing a person who is unconscious to breath. Buoyancy aids and lifejackets largely fall in to 4 categories, listed below, but as above you must first decide what rating you want your buoyancy aid or lifejacket to be, then buy it in a size that fits you.

Types of Life Jacket Inflation (Guide Purposes Only):

Automatic Lifejacket Inflation. These life jackets work on the principle that an element in the inflation mechanism reacts with water (in most cases this ia a pill/pellet that dissolves in water), automatically triggering the gas cartridge, which in turn inflates the air chambers of the lifejacket.

Automatic Lifejackets are a popular choice due to the reassurances of an auto firing mechanism, ideal if you're knocked unconscious when you hit the water.
Automatic Lifejackets will also have a manual inflation mechanism as well.

Manual Lifejacket Inflation. These lifejackets work by operation from the user, the lifejacket will have a pull chord or string that needs to be pulled firmly, this fires a pin triggering the canister to inflate the lifejacket.

Oral Life Jacket Inflation. The third method of inflating your lifejacket is by means of you manually blowing up the lifejacket. Located in the lifejacket where the lung is will be a mouth piece, this can be used as a fail safe to blow up the lifejacket, or to top up the air in an already inflated lifejacket.

Life Jacket and Buoyancy Aid Newton Ratings (Guide purposes only):

Life Jacket Buoyancy is measured in Newtons (N), 10N = 1Kg of Flotation.

There are Four European Standards for lifejacket buoyancy. All Lifejackets must have an Approved CE Mark.

50 Newton Buoyancy. Standard Newton rating for Bouyancy Aids, recommended for usage for swimming in sheltered and attended waters, with assistance close by. The buoyancy level does not guarantee to self right a person in the water.
Buoyancy Aids are popular with people who find their activities always have them in the water! Examples being windsurfing, dinghy sailing and water skiing.

50N Buoyancy Aid (EN393 / ISO12402-5) – A flotation device that is designed to enhance the wearers safety in water, but is to be used by competent swimmers as this will not turn the wearer in to a position that keeps the airway clear. The European standard does not allow these to be rated for smaller children, so a minimum weight of 25kg has been imposed on this rating.

100 Newton Buoyancy. A lifejacket suitable for those who are likely to be in calm and sheltered waters. It is unlikely to provide enough buoyancy to protect someone who can't fend for themselves, and crucially it may not be strong enough to self right an unconscious person onto their back, especially if the person is heavy in weight, or wearing lots of heavy items of clothing.

100N Lifejacket (EN395 / ISO12402-4) – A flotation device that is designed to keep a person afloat with their airway clear of the water in sheltered and inshore waters. This rating is normally applied to fixed foam type lifejackets, as to make these in the higher 150N category would make them too large to wear. Fixed foam lifejackets are recommended for non swimmers due to their immediate buoyancy when the wearer enters the water.

150 Newton Buoyancy. A suitable lifejacket for inshore and Coastal sailing. The buoyancy level should also mean that it can cope with general offshore sailing and rougher weather. It should self right an unconsciuos person onto their backs, and crucially keep their face out of the water. It's performance may be affected if the user is wearing heavy and waterproof clothing.

150N Lifejacket (EN396 / ISO12042-3) – A flotation device that is designed to keep a person afloat with their airway clear of the water. It has more buoyancy than the 100N class, so turning performance (how quickly the user is rotated on to their back) is enhanced, and so called freeboard (how high the wearers airway is kept our of the water) is higher. These are therefore generally suited to sailing in worse conditions than the 100N standard. Most self-inflating lifejackets carry this standard, as the bladder of a 100N jacket is almost the same size as a 150N when deflated and packed inside the outer cover. Self inflating lifejackets are intended for competent swimmers only, as they take a few seconds to inflate and somebody panicking could inhale water during this time.

275 Newton Buoyancy. A suitable lifejacket for offshore cruising and commercial sailing. Suitable levels of buoyancy for the most extreme weather conditions out on the water, and they're designed to work with people who will be wearing full foul weather clothing. The lifejacket will self right the wearer onto their back, and keep their face out of the water.

275N Lifejacket (ISO12402-2) – These lifejackets have a huge amount of buoyancy and as a result are quite bulky even in self-inflating form. They are generally only used in commercial applications, where heavy clothing or drysuits could impede the turning performance of a 150N class device. Needless to say, these jackets have a very impressive turning performance, and normally a very high freeboard. Bigger isn’t always better though, and it must be taken in to account that these jackets can make movement very difficult once inflated, seriously inhibiting a persons ability to self-rescue by, for example, climbing a ladder or entering a liferaft.

Other Newton Ratings – Lifejacket manufacturers have taken to advertising their jackets as the actual Newton rating, so for example you may see jackets advertised as 165N or 190N. This reflects the actual buoyancy rating in Newtons, and while useful for comparing jackets, in the eyes of the EU or ISO standard, if a jacket meets or exceeds one of the above ratings, that is the standard to which it conforms. For example, a 165N lifejacket will conform to the 150N EN396/ISO12402-3 standard, and as such is a ‘150N Class’ lifejacket.

Happy Sailing!