Usability as a life saver: Diving — Part 1

Diving: Relying on a functioning equipment
As you slowly descend into the infinite blue surrounding you, you focus on your breath: inhale, exhale regularly. Don’t hold your breath. Bubbles stir up as you deflate your vest. You balance the pressure in your ears while scanning the underwater world beneath you. Single fish pass by, ignoring your presence. In the distant blue you make out a dark object, blurry at first but getting clearer with each meter you drop lower. From the side of your eye you see your dive buddy in an arm length’s reach. Suddenly you can make out first characteristic features below: you see the rectangular shape, pointy to the front. You check your diving computer: 18 meters deep. You should soon be there. 20m — you see dots of different sizes and shapes moving around the dark object. 25m — you recognize a box-like form on the rectangle: the bridge, fish swimming in and out of it through empty window frames. 28m — finally you have reached your destination for today’s dive: the wreck of a German P-29 patrol boat.

Somewhat like this was my experience when I dived down to my first wreck. Incredibly amazing, yet a little scary. In all the situations I have experienced during diving so far, I was relying on my dive training but even more on the equipment I used. Only after some time I realized just how important good usability is for diving. Let me explain.

In general, usability describes the amount in which a device or service is efficient, effective and satisfying in supporting the user in fulfilling his need or task. Good usability of devices or machines is even more important when it comes to high risk environments. Always being aware of the system’s state, knowing how to use it and trusting it is crucial. This accounts for aviation, power plants, the medical operating room and other areas where a failure in a critical situation can be fatal.

Likewise, as a scuba diver you depend on your equipment, probably more than in most other sports or activities (besides maybe bungee jumping or skydiving).

Maintaining and preparing the equipment is essentail for a safe dive.

You need your mask for a clear view, your neoprene suit to protect your body from hypothermia and fins to swim. Further, the core of scuba diving: your breathing device, connected to a tank filled with compressed air on your back. The tank’s air supply is also connected to your BCD (Buoyancy Control Device), a vest you in- or deflate to rise, float or sink. In addition, you carry weights with you to account for the weight your tank looses through the air you consume during the dive and to compensate for the positive buoyancy of the wetsuit and your body. This is the basic equipment. Nowadays, most divers carry a diving computer with them to indicate the remaining dive time at a certain depth, as well as additional gear such as a camera, torches, a signaling device or a dive knife.

This equipment must fulfill the following requirements which in combination contribute to a good usability:

Ergonomic design: Wearing your BCD with the tank on the back is uncomfortable on land but as soon as you are in the water, you barely notice it due to the reduced gravitational forces underwater. Still, the equipment can be bulky and your freedom of movement may be reduced due to additional equipment such as torches, cameras or signaling devices clipped to your vest. The design and layout of modern BCDs are made to fit to the diver’s physiology and support the diving task. Therefore, important parts are comfortably reachable. For example, the inflator can always be grasped with the left hand and is shaped to easily lie in your hand: you press with your thumb to inflate your vest and use the button under your index finger to deflate.

Once you reach the right buoyancy thanks to an easily usable equipment, you forget about the bulky gear and can enjoy the dive.

Simplicity: Whereas a wide-ranged functionality is an often desired quality for devices, having a great variety of settings is out of place underwater. Tasks that seem basic on land can be quite tricky while diving, such as taking notes. Not only the different physical properties complicate manual tasks but also the increased pressure in greater depths can have severe effects on reaction time and mental skills. This is why diving equipment should be kept simple. Most diving computers for example only have few buttons and limited customization features (at least underwater). Also, most cameras and torches only possess a few mostly big buttons, made for the use with gloves.

Operating gear with gloves can be an additional challenge

Efficiency and effectiveness: If you encounter a severe problem underwater, it is crucial to react as fast as possible. For example, the weight systems you use are meant to be handled quickly: you have to be able to drop them easily in an emergency situation to reduce weight. This is why weight systems are mostly either worn as a belt which can be opened quickly or stuck into the vest, so that you can pull them out with one quick grasp.

Efficiency: adjusting a weight made of lead underwater can be tricky if it is fixed on the tank.

Self-descriptiveness & clear feedback: You can’t look up a user manual or easily ask your dive buddy for instructions when you are diving. Thus, the system must be self-describing and intuitive and the feedback you receive must be unambiguous. Displays of dive computers are therefore kept simple, avoiding fancy visuals but focusing on the most important information (depth, no decompression time and dive time). Some dive computers also use auditive feedback, such as a beeping tone when you surface too quickly. However, the most important information — the remaining air — is still shown on a separate analogue display connected to the tank and not on the dive computer. There are new dive systems which are mounted to the tank so that the status of your air supply can be sent directly to your dive computer in order to have all important information on one spot. So far, these systems are promising, yet further development is needed to ensure their reliability.

The dive computer shows the depth, the remaining time at this depth without needing a decompression stop, and the dive time (left). In addition, the analogue display shows the current depth and the remaining air (right).

Rules & standards: There are some common rules and standards all manufacturers of diving equipment adhere to. For example, the second breathing device which you carry in case of you or your dive buddy running out of air is standardized. It is fixed on your right chest or shoulder and it is always yellow (whereas the rest of your equipment is mostly black). Divers themselves also stick to clear rules. For example, one of the first things you learn is never to show the “thumbs up” if you are OK since it means “surface”.

International rules & standards for diving. Left: giving the “OK” signal | Right: the yellow color clearly marks the tube of the second breathing device.

The improvements in diving technology throughout the last decades have made recreational diving as safe, fun and comparatively easy as it is today. Focusing on usability and user experience has contributed largely to this advance. Considering current developments in technology and their influence on user experience such as Augmented, Virtual or Mixed Reality (AR/VR/MR) and Artificial Intelligence (AI), which future developments in diving could there be? See Usability as a life saver — Part 2.