Many people, especially those of a smaller build, are frustrated because they can't find a BCD that fits them. There is a solution. I begin with a tragic tale. In 2014, off the Coromandel Peninsula in New Zealand, a diver on a discover scuba experience died when she became separated from her group and ran out of air. She was discovered on the surface, floating face down. The inquest found that the dive operation involved was to blame because they had failed to supervise her properly. They were also criticised for having given her a BCD that was too large and that made it “difficult for her to lift her head and breathe”, as the verdict read.

The chief health and safety inspector who conducted the investigation into the death was quoted as saying: "the ill-fitted equipment compromised the victim's ability to try and breathe when her air supply ran out. It also meant she couldn't tell anyone she was in distress, or get help”. Evidently, the diver ran out of air but actually made it to the surface alive, where she then drowned because of her over-sized BCD. The lack of supervision put her in difficulty but it was the BCD that killed her: a tragedy that was completely preventable.

Poorly fitting rental equipment is all too common and BCDs are the main problem, especially for slimmer adults and children. You often see smaller-framed individuals and teenagers on scuba try-dives and courses for beginners, floating on the surface in a pool or the ocean, lost inside their inflated BCD with the shoulder harness straps hovering above their ears and their head partly submerged.

I have spoken to a number of people over the years, whose first experience of scuba diving was so unpleasant because of an over-sized BCD that they never dived again.

It is a systemic problem within the dive industry, but there is a solution and it is being adopted widely in Asia, where, for most people, scuba diving is still relatively new and many scuba divers are of smaller build. I should mention here that the diver who died off the Coromandel Peninsula was Asian and she was diving in a country where the majority of the diving population is not small of build. It may well be that the BCD that was too big for her was the smallest size the dive operation had.

The solution to the problem is a harness that hugs the body, with straps over the shoulders, around the waist and between the legs, attached to a back mounted air cell. The common terminology for this style of BCD is a harness and wing. The air cell is the wing.

This is not a new style. It was developed by cave divers a couple of decades ago and then universally adopted by technical divers.

It is a design that holds the head higher on the surface than a conventional jacket-style BCD, is easier to control and does not squeeze the ribcage and inhibit breathing when the air cell is fully inflated. The harness also permits every diver, whatever their shape and size, to have a BCD that fits them perfectly, as all the straps can be lengthened or shortened to match the individual.

However, today, standard jacket-style systems are still more commonly seen, particularly in dive centre rental fleets. Why is this, when a harness and wing offers so many advantages?

A number of factors are responsible. First, harness and wing designs have always been more expensive than jacket-style BCDs. This means that, for financial reasons, dive centres have continued to buy jacket style options for training and rental use.

So, not only do new divers get used to using jacket-style BCDs, they are often unaware that an alternative even exists. It may sometimes be the case that their more knowledgeable instructor is wearing a harness and wing but the students’ minds are probably so occupied with other things that they do not even notice.

Second, many harness and wing systems have a solid aluminium or stainless steel backplate. Until very recently, these have been mostly one-size-fits-all and uncomfortable to wear, unless your body contours match the plate exactly and you wear plenty of neoprene.

Third, very little thought was given to creating wings for the wider market of divers who were not diving with multiple cylinders. Wings designed for use with double cylinders were much too big for single cylinder diving and added unnecessary drag when a diver was swimming.

Finally, despite the fact that, several years ago, scuba diving entered an era where the majority of new divers were women, smaller men or teenagers, few manufacturers responded with designs that suited the body shapes of this new market.

This has changed. At a dive exhibition in Asia recently, I noticed a crowd around one of the stands and stopped to see what the excitement was all about. I saw a small teenage boy standing there wearing a wing and harness system that fitted him perfectly. Most of the people drawn to the stand were discussing how well the harness would fit them and how unobtrusive and streamlined the wing looked.

In a region where almost everyone has to fly somewhere to scuba dive, the onlookers were also impressed by how little this wing and harness system weighed. Despite the fact that the wing had both an outer and inner bladder all the D-rings, slides and the harness buckle were premium stainless steel and it had two cylinder bands, the total weight was under 3kg (7lbs).

A few months later, I noticed another manufacturer in Europe selling a wing and harness, sized for what they referred to as a “youth” market. It also looked perfect too for adults who find that even extra-small European and US sizing is still too big for them.

I close this story with a much happier tale than the one I began it with. A while ago, I mentioned the advantages of harness and wing systems to a friend named Karen, who is a petite, slim, fit New York lawyer. She was complaining that, in all her 20-plus years of diving, she had never been able to find a BCD that fit her well. She had tried extra small options from a variety of brands, as well as BCDs supposedly designed for ladies, and had found that they were either still too big for her or did not offer sufficient stability.

I suggested a soft-pack harness with a small wing, manufactured by Dive Rite, a company in Florida. I did not give the conversation any further thought until I met up with her again a year or so later. She threw her arms around me in an unusually enthusiastic welcome and said she wanted to thank me. She had tried the harness and wing that I had suggested. Her local dive centre helped her set up the harness so that it fit snugly. They also made sure her weight pockets were in the right place, added a small pouch and removed all the D-rings she was not going to use. It had transformed her diving life.

She said she had never experienced anything so effortless and comfortable. What is more, she was delighted to find that she now only needed to carry 2kgs (4.5lbs) of weight when she was wearing her 3mm wetsuit, instead of the 4kgs (9lbs) she had required before. I believe there are many other Karens out there who need a similar transformation in their diving life. If you know one, please pass on the message.

This blog post is adapted from a chapter in Scuba Exceptional - Become the Best Diver You Can Be.