Who needs to wear a life jacket on a boat?

Who needs to wear a life jacket on a boat?

The term “life jacket” can be used to describe a number of different types of personal flotation devices (PFD). If you happen to fall overboard a PFD is one of the most effective ways of saving your life and increase your chances of survival. The most common of these are buoyancy aids, foam lifejackets and gas inflated life jackets. We’re going to show the different types and what they are best used for.


Irish legislation
The legal bit first. In Ireland, the law requires that an appropriate life jacket or buoyancy aid must be carried for everyone onboard all vessels and personal water craft. If the craft is under 7m, personal flotation devices must be worn at all times on an open vessel or on deck on a vessel with accommodation. Anyone under the age of 16 must wear a personal flotation device at all times on an open boat or on deck if the vessel has accommodation, irrespective of the size of the vessel. 

Buoyancy Aids 50N

Level 50 buoyancy/floating aids are designed to keep the wearer afloat, but not to turn a person from a face/down position in the water. This level is ideal for use in sheltered waters or where help is close at hand. While a buoyancy aid will provide decent flotation and increase confidence they do not have sufficient buoyancy to protect a person who is unable to help themselves ie. if someone gets knocked out from a bang to the head a buoyancy aid won’t be enough to right the person.  Activities include swimming, dinghy sailing, kayaking and paddle boarding.

Foam Life Jackets 100N

Level 100 life jackets are designed for those who may have to wait for rescue but would do so in sheltered and calm waters. It may not have sufficient buoyancy to protect a person who is unable to help themselves and may not roll an unconscious person onto their back. Activities include those above but where the person would feel more comfortable and confident with a higher level of buoyancy. They are also a good option for children as the inherent buoyancy means there is no need for the child to do anything if they fall in.

Gas Inflated Life Jackets 150N

Level 150 life jackets are designed for use on coastal and offshore waters where a high standard of performance is required. It should turn an unconscious person on to their back and requires no subsequent action by the wearer to keep their face out of the water. Yet, its performance may be affected if the user is wearing heavy and/or waterproof clothing. These jackets come in non-harness and harness versions. Harness versions you can attache a safety line (tether) to the life jacket and secure yourself to the boat. Non-harness is mainly for inland waters and RIB use. Harness versions are best for yacht racing and coastal/offshore use. Offshore jackets will have extra features such as lights and spray hoods. These can also be retro fitted to any inflatable jacket.

Gas Inflated Life Jackets 275N

Designed for offshore use in extreme conditions, often for those wearing heavy protective clothing that may adversely affect the self-righting capacity of lesser lifejackets. Like level 150, this life jacket is designed to ensure that the wearer is floating in the correct position with their mouth and nose clear of the surface of the water. Ideal for use in offshore & ocean racing and commercial workers where additional clothing and tools are involved


There are three inflation methods for gas-only life jackets. Most inflatable life jackets are inflated by piercing a bottle filled with carbon dioxide (CO2) attached to a firing head. Orally-inflated-only lifejackets (ones without a gas cylinder) are not recommended for everyday use.


Manually inflated life jackets are operated by pulling a cord that pushes a firing pin into the CO2 bottle, inflating the life jacket. With manually inflated activation, there is no risk of false activation which could happen when a wearer is hit by a large wave. The downside of manual activation is that it will not work when the wearer is unconscious or suffering from cold water shock. 


Automatic water-activated life jacket

Most people choose a life jacket that will inflate automatically if they enter the water.

This life jacket works by water-activated automatic firing heads with a small pellet or bobbin that holds back a strong spring. When the pellet/bobbin touches water, it dissolves quickly, releasing the spring which pushes the firing pin into the gas bottle, inflating the life jacket.

Automatic pressure-activated life jacket also called Hydrostatic or Hammar

Choose this type of lifejacket if you take part in an activity where you are regularly soaked by waves or sea spray because it won’t fire unless fully submerged in water. Hydrostatic (Hammar) life jackets work the same way an automatic life jacket (with a dissolving pellet) but the pellet is protected by a case. Water can only get in once it is a few centimeters underwater. 

Another bonus: CO2 bottles in pressure-activated life jackets are less likely to suffer from corrosion.

Manually inflating automatic life jackets

You can always manually activate automatic life jackets. The primary way to manually inflate a life jacket should be the pull cord. Always try to inflate your life jacket before entering the water. Newer life jackets may have indicators to show if gas bottles are empty or if automatic firing systems have been triggered.


Servicing and Re-Arming

It’s important to have your gas inflating life jacket serviced every 2 years. 

An automatic life jacket consists of 2 parts, the CO2 cylinder and the firing cap. If the jacket has been deployed you will most likely need to replace both parts. If the firing cap has reached the expiry date you will only need to replace this piece. The CO2 cylinder doesn’t have an expiry date however, it should be replaced if corrosion occurs. 

A hydrostatic system also has 2 parts both of which will need to be replaced when re-arming.

A manual jacket only consists of the CO2 cylinder so will have no expiry date. The jacket should still be serviced every 2 years and the cylinder replaced when corrosion occurs or when fired. 


Did you know that all adults, regardless of their size, weigh approximately 5kg/11lbs when immersed in water? Therefore, you don’t need a higher Newton level PFD just because you’re big. However, level 100 buoyancy aids and life jackets usually come in a broad range of sizes (from baby to XXXL). Even if the buoyancy level doesn’t change, it’s important to find one that fits correctly so it's comfortable to wear.


Ensure that your buoyancy aid is the right size by doing this quick check: put on the jacket and try to lift from the shoulders. If you can move the jacket, it’s too big (or not tight enough). Try a smaller size or a snugger fit.


Crotch straps should be secure and all other straps adjusted correctly. If the life jacket belt is not securely fastened, the life jacket will rise above the shoulders and reduce its effectiveness.

Familiarize yourself with the buckles on your life jacket and make sure that the belt does not slack. Try fitting the belts properly before you buy your life jacket.



Look for a slimmer cut that allows freedom of movement around the boat. It should be high cut to allow bending and a trapeze harness. A dingy jacket should have a smooth exterior to avoid getting caught on the rigging. Because rescue is typically close at hand, a 50N buoyancy aid should suffice. Carry a knife to avoid entrapment in the event of a capsize. 


For swimmers with rescue close at hand, a 50N PFD can work well. For non-swimmers, or when rescue is not close at hand, a higher Newton life jacket is recommended. 


When you’re venturing farther from land, a higher Newton life jacket is necessary. Look for at least 150N. A deck harness is another important feature.  


Look for life jackets or buoyancy aids that are cut away around the shoulders and the arms. You need to maintain mobility for paddling and swimming. Ensure that the life jacket has a belt or a drawstring to pull tight around the chest. Bright colors that are easy to spot are also important. 


Whitewater rafting PFDs require more buoyancy to keep you above water in fast currents. Therefore, they’re also bulkier. The fronts are also high cut to allow you to lean forward comfortably. A whitewater rafting life jacket must be secured tightly to ensure it’s not ripped off by water pressure. It must also have at least one pocket for rescue equipment and have a smooth, snag-free exterior.


A buoyancy aid should be comfortable, but it does not have to be sport-specific. Find the right level of buoyancy in the right size, and your buoyancy aid can work for many watersports. But, double-check that it has a minimum buoyancy of 50N.


                                              Authors Bio 

John Tully has been wearing and selling life jackets for over 40 years. He has training in servicing and re-arming all types of life jackets and life rafts. From Spinlock to Crewsaver and Marinepool to Seago, John can do it all.

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