As I plunge into the sea off the east coast of Iceland, the water temperature shows 6°C and the cold is enough to take the breath away. I am wearing a drysuit but my face, head and hands all feel like they have been hit by a block of ice. I’m instantly fully submerged but already I can feel and hear the reassuring pop and crackle as the automatic inflation system on my lifejacket activates.

Resurfacing, with the big yellow bladder of the inflated jacket all around me, I need to get my face covered by a sprayhood as quickly as I can, find my whistle, check my light is working and then hopefully have the rescue boat extract me from the water. In just a few seconds my hands are going numb, even with my sailing gloves on, and my body is aching from the cold; the thought of being in this situation in the dark and with stormy seas is hugely sobering. In real life, survival can be measured in minutes and everything has to work perfectly, yet we faced problems with each jacket we tested.

Rubicon 3 expeditions head off to some pretty inhospitable waters throughout the north Atlantic and up to the Arctic. Last year alone we completed more than 100 practice man overboard rescues. With our own lifejackets approaching the end of their useful life, we were interested to put three of the leading products to the test. We selected the Spinlock Deckvest 5D, the Helly Hansen Inflatable Racing Jacket and the Crewsaver Ergofit Extreme 290N.

We look for three key criteria in a lifejacket. First, it has to be comfortable and practical to wear. It is going to be on the shoulders for hours at a time and you should be able to forget that it’s there. Second, we look for ease of use and adjustment. Sailing often requires the rapid donning of a jacket or foulies and the extra bulk means the lifejacket harness needs to be easily adjusted to keep it properly fitted. Third, the jacket has to perform perfectly if a casualty were to fall in the water.

There is no margin of error here. It has to work first time, every time and it has to be idiot-proof. On most boats, neither the casualty nor the rescuer is likely to have seen the jacket in its deployed state. Its sprayhood, equipment and lifting strop have to be intuitive, easily accessible and highly effective.

How they performed

Older lifejackets had a habit of weighing down on the shoulders and rubbing against the back of the neck. It made them uncomfortable to wear for any period of time and probably acted as quite a disincentive to wear one. On that front, all three jackets we tested were superb. So much thought and design has gone into each one and they sit nicely on the shoulders and away from the neck.

We wore each jacket for many days at a time and were very happy with each. Of the three, we found the Helly Hansen jacket to be the most comfortable, possibly as a result of it also being the smallest. Considering its size, the Crewsaver was far more comfortable than we thought it would be. The Spinlock seemed to sit the highest on the shoulders and very slightly obstructed the neck when looking up, but any differences were so minor as to fall into the personal preferences category. Indeed, greater experience with the fitting of each jacket could well have eliminated any problems at all.

Fitting the jacket

Each jacket has a different fastening system. The Crewsaver has very seductive dual plastic fastenings that take just a second to snap in to place. Anyone who has struggled to get a metal buckle inside another buckle (the traditional lifejacket fastening) will recognise the appeal of this system. The Spinlock has a bespoke high tensile fibre buckle that always proved easy to use, while the Helly Hansen jacket sticks with the metal buckle in buckle.

We do love the Crewsaver system for its simplicity, but have that nagging worry that it will get damaged. Equipment and people get thrown around at sea and it could just take someone standing on the mechanism to break the plastic. The Spinlock and Helly Hansen systems are effectively unbreakable and, of the two, the plastic version is both easier to use and quieter when attached to a metal tether hook.

Adjusting the jacket

We really liked the Helly Hansen’s big, adjustable straps at either side of the body, which pull forward, making it straightforward to put on a loose jacket and then adjust to size once on.

The Crewsaver jacket has a similar system, but its adjustment buckles are further back. To prevent them locking against the body, they have to be pulled out sideways rather than forward. Crewsaver says this buckle placement makes for a stronger harness. Maybe, but for us it simply made the jacket difficult to adjust and was a frustration.

The Spinlock has small adjuster buckles that can be pulled tight at the front. These worked very well and allowed for rapid adjustment. It was also the only jacket to have an adjusting buckle at the shoulders.

What is my Newton rating?

Any sailor venturing offshore should have at least a 150N jacket. This amount of buoyancy will give a good level of protection against drowning, working with the design of the bladder to roll an unconscious casualty on to his or her back. However, bear in mind that clothes and foul weather gear can trap lots of air underwater and this can counteract the lifejacket’s intended righting moment. This may mean a delay to larger casualties being brought face-up in the water. The much greater level of buoyancy of a 275N jacket reduces this delay.

Sprayhoods

Not all jackets have a sprayhood fitted but if you are ever likely to be venturing out into heavy weather it is a small, cheap addition that you should definitely have. In heavy weather, there will be a great deal of spray above the water and there is a very real risk of spray inhalation and secondary drowning.

Thigh/crotch straps

It is essential that you have a crotch strap, or straps, fitted and snugly tightened. The straps keeps the lifejacket close to the torso, improving flotation angle and keeping the airway clear. They also prevent the casualty falling out of the lifejacket when being lifted out of the water. RNLI research shows that snugly fitted crotch straps increase survival rates by up to 30 per cent in comparison with jackets that do not have them fitted.