Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team.
Divers communicate in several ways:
Voice – Most professional diving equipment such as full face diving masks and diving helmets incorporate some sort of voice communication equipment
Video – Surface supplied divers often carry a closed circuit video camera on the helmet which transmits visual data to the surface control team, as well as permits the sue of hand signals as a backup (in case the primary voice comm fails).
Text – This simply implies underwater slates which may be used to write text messages or the use of some dive computers which allow a limited number of pre-programmed text messages to be sent through water to other divers or surface personnel.
Hand signals – Recreational divers do not usually have access to voice communication equipment, and in any case these systems generally do not work with a standard scuba demand valve. As a result, hand signals are generally used when visibility allows.
Line signals (rope pulls) – Rope signals can be used if the diver is connected to another diver or tender by a rope (or, in case of surface supplied diving, an umbilical. There are several standardized signals mostly used as backup by professional divers in the event that main communication fails. Additionally, these can be of use to technical divers who can use their SMBs to communicate with boat crews without emerging from depth.
Light signals – The difficult option is to transmit Morse Code signals, but that is a dying skill. Today there are only a handful of light signals used by divers.
Cave line symbols – These are symbols attached to cave lines, indicating important information such as the location of, or direction to the exit.
Sign language — Divers who are familiar with a sign language such as American Sign Language find it useful underwater. However, there are some limitations due to the difficulty of performing some of the gestures in a clear fashion while wearing gloves or trying to hold something.
Tap codes – Made by knocking on the walls, are used occasionally to communicate with divers trapped in a sealed bell or the occupants of a submersible during a rescue. May rely on Morse Code.
Rattle – A tube containing ball bearings used by guides to attract attention.
Miscellaneous emergency signals – This includes the use of mirrors, compressed air sirens, whistles, noisemakers, colour-coded Delayed Surface Marker Buoys, smoke, dye etc., to alert the surface support personnel of a problem
Diver down signals – The dive flags, lights and shape signals used to indicate the presence of divers in the water.
Of most importance/relevance to divemasters and instructors are various hand signals which they can use to communicate with students or assistants in order to ensure quality of teaching, comfort, and safety.
Here is a number of commonly used hand signals. It is a good idea for new divemasters to familiarize themselves with these, practice often (it’s perfectly acceptable to do this at the bar), and incorporate them into your day, and you will immediately see an improvement in your underwater communication.
Obviously there are dozens more that we will go over in class as well during various dive briefings. It is ok to use variations of hand signals, as long as all members of your team are properly briefed on their meaning and usage.