Human factors in diving equipment design is the application of human factors and ergonomics principles and data to the design of diving equipment and diving support equipment to facilitate diver-system interactions and provide for diver wellbeing and overall dive efficiency. The underwater diver relies on various items of diving and support equipment to stay alive, healthy and reasonably comfortable and to perform planned tasks during a dive. Divers vary considerably in anthropometric dimensions, physical strength, joint flexibility, and other factors. Diving equipment should be versatile and chosen to fit the diver, the environment, and the task. How well the overall design achieves a fit between equipment and diver can strongly influence its functionality. Diving support equipment is usually shared by a wide range of divers and must work for them all. When correct operation of equipment is critical to diver safety, it is desirable that different makes and models should work similarly to facilitate rapid familiarisation with new equipment. When this is not possible, additional training for the required skills may be necessary. The most difficult stages for recreational divers are out of water activities and transitions between the water and the surface site, such as carrying equipment on shore, exiting from water to boat and shore, swimming on the surface, and putting on equipment. Safety and reliability, adjustability to fit the individual, performance, and simplicity were rated the most important features for diving equipment by recreational divers. The professional diver is supported by a surface team, who are available to assist with the out-of-water activities to the extent necessary, to reduce the risk associated with them to a level acceptable in terms of the governing occupational safety and health regulations and codes of practice. This tends to make professional diving more expensive, and the cost tends to be passed on to the client. Human factors engineering (HFE), also known as human factors and ergonomics, is the application of anatomical, psychological and physiological principles to the engineering and design of equipment, procedures, processes, and systems. Primary goals of human factors engineering are to reduce human error, increase productivity and system availability, and enhance safety, health and comfort with a specific focus on the interaction between the human and equipment.
General principles Diving equipment is used to facilitate underwater activity by the diver. The primary requirements are to keep the diver alive and healthy, while secondary requirements include providing comfort and the capacity to perform required tasks. Safe operation requires correct equipment function as well as diver competence. Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of some of its components. If its operating quality decreases at all, the decrease may be proportional to the severity of the failure. Diving equipment, especially hardware elements that are high availability or safety-critical systems, must have a high fault tolerance. The ability to maintain functionality when portions of a system break down is referred to as 'graceful degradation', as opposed to a small failure causing total breakdown. The diver must also be fault tolerant, a state that is achieved by competence, situational awareness and fitness to dive, .
Physiological variables
Task loading, nitrogen narcosis, fatigue, and cold can lead to loss of concentration and focus, reducing situation awareness. Reduced situation awareness can increase the risk of a situation that should be manageable developing into an incident where damage, injury or death may occur. A diver must be able to survive any reasonably foreseeable single equipment failure long enough to reach a place where longer-term correction can be made. The solo diver can not rely on team redundancy, and must provide all the necessary emergency equipment indicated as necessary by the risk assessment. On the other hand, a team can reduce risk to an acceptable level in most cases by distributing redundancy among its members. However, the effectiveness of this strategy is tied to team cohesion and good communication. No gender-specific traits have been identified which require design of tasks and tools exclusively for female divers. Fit of diving suits must be tailored to suit the range of human shapes and sizes, and most other equipment fits all sizes, is adjustable to suit all sizes, or is available in several sizes. A few items are designed specifically for female use, but this is often more a fine tuning for comfort or cosmetic styling than an ergonomically functional difference. Female divers are reported, on average, to experience greater difficulty in performing five tasks of recreational diving: carrying heavy equipment on shore, putting on the scuba set, underwater orientation, underwater balance, and trim and descent. The first two are related to lifting large, heavy and bulky equipment. Balance and trim could be related to buoyancy and weight distribution, but insufficient data is available to specify a remedy. There is a relative growth in the older sector of recreational diver demographics. Some are newcomers to the activity and others are veterans continuing a long career of diving activity. They include older female divers. More research is needed to establish the implications of age and sex-related variations on human factors and safety issues.
Breathing apparatus
The breathing apparatus must allow the diver to breathe with minimal added work of breathing, and minimum additional dead space. It should be comfortable to wear, and not cause stress injury or allergic reactions to its materials. It must be reliable and not require constant attention or adjustment during a dive, and performance should degrade gradually in the event of malfunctions, allowing time for corrective action to be taken with minimum risk. When more than one breathing gas mixture is available, the risk of selecting a gas unsuitable for the current depth must be minimised.
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