The general requirements for an effective system for diver communication are that all the people who will use it have access to the system, that it functions effectively in the specific environment, that the people who wish to use it are familiar enough with it to communicate quickly, accurately and unambiguously with each other, and that the system has sufficient range to work when needed. Voice communication is natural and effective where it is practicable, and most people rely on it for fast and accurate communication in most circumstances. The equipment used by divers and the pressurised environment are also hindrances to sound-based communication, and the encumbrance of diving equipment, relatively low light levels, and low visibility of many diving environments also hinders visual communication.Ĭommunication is most critical in an emergency, where high stress levels make effective communication more difficult, and the circumstances of the emergency may make the communication physically more difficult.
The interface between air and water is an effective barrier to direct sound transmission, and the natural water surface is also a barrier to visual communication across the interface due to internal reflection, particularly when not perfectly smooth.
These signals are often also used by professional divers to communicate with other divers.
Hand signals are generally used when visibility allows, and there are a range of commonly used signals, with some variations. Recreational divers do not usually have access to voice communication equipment, and it does not generally work with a standard scuba demand valve mouthpiece, so they use other signals. Voice communication is the most generally useful format underwater, as visual forms are more affected by visibility, and written communication and signing are relatively slow and restricted by diving equipment.
This prevents divers from performing at their full potential. Ĭommunication between divers and between surface personnel and divers is imperfect at best, and non-existent at worst, as a consequence of the physical characteristics of water. Underwater slates may be used to write text messages which can be shown to other divers, and there are some dive computers which allow a limited number of pre-programmed text messages to be sent through-water to other divers or surface personnel with compatible equipment. This can also be used to transmit hand signals to the surface if voice communications fails. Surface supplied divers often carry a closed circuit video camera on the helmet which allows the surface team to see what the diver is doing and to be involved in inspection tasks. The traditional method of communication was by line signals, but this has been superseded by voice communication, and line signals are now used in emergencies when voice communications have failed. This is considered important both for managing the diving work, and as a safety measure for monitoring the condition of the diver. In professional diving, diver communication is usually between a single working diver and the diving supervisor at the surface control point. Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team.