How Do Life Jackets Work

I Like Pessimists, They’re always the ones who bring life jackets for the boat

— Lisa Kleypas

We all know about life jackets, we know that if we fall in the water it goes poof and suddenly, we are saved, but how? What causes the seemingly automatic function to save your life in your direst moments, it’s all down to a set of mechanisms, all working hand in hand to cause the inflation that we all see.

The life jacket itself is only half the cake, one of the most important pieces, and one of the most overlooked is the beacon. Most professional life jackets will require a beacon, a beacon uses radio signals to tell the nearest ship or land mass that you are in the water, you are drifting, and you need help.  Some beacons are linked to a specific receiver on board your vessel, other signals can go straight to the emergency services.

There are of course jackets that don’t set off automatically. Manual inflated life jackets are activated by pulling a cord, releasing the firing pin mechanism into the pressurised gas cylinder, releasing the gas and inflating the life jacket. Manual life jackets however would not be peoples first choice due to the dangers of cold-water shock. Those going into shock will hyperventilate, panic and pulling a cord could prove very difficult.

But what about the automatically inflated ones?

So, you fall into the water and luckily you are wearing an automatic inflating life jacket, what happens to cause it to blow up? Its all down to a clever little tablet called a bobbin, the bobbin acts as a buffer between the firing pin and the gas cylinder, the bobbin dissolves, allowing the firing pin to hit the cylinder, thus activating the mechanism.

Once the jacket is activated, the extension of the jacket itself causes a cord to be pulled from the beacon, setting off a signal for you to be found as soon as possible, safely floating in the water.