Diver communications

A diver touches his first finger tip to his thumb tip while extending his other fingers
The hand signal "OK"
Emergency tap code signboard on a closed diving bell
A list of tap codes may be fixed to the exterior of a closed bell to ensure mutually understandable communication.

Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team.

There are several distinct forms of diver communications:

Voice communications

Both hard-wired (cable) and through-water electronic voice communications systems may be used with surface supplied diving. Wired systems are more popular as there is a physical connection to the diver for gas supply in any case, and adding a cable does not make the system any different to handle. Wired communications systems are still more reliable and simpler to maintain than through-water systems. The communications equipment is relatively straightforward and may be of the two-wire or four-wire type. Two wire systems use the same wires for surface to diver and diver to surface messages, whereas four wire systems allow the diver's messages and the surface operator's messages to use separate wire pairs.

A standard arrangement with wired diver communications is to have the diver's side normally on, so that the surface team can hear anything from the diver at all times except when the surface is sending a message. This is considered an important safety feature, as the surface team can monitor the diver's breathing sounds, which can give early warning of problems developing, and confirms that the diver is alive.

Divers breathing helium may need a decoder system which reduces the frequency of the sound to make it more intelligible.

Through water communications systems are more suitable for scuba as the diver is not encumbered by a communications cable, but they can be fitted to surface supplied equipment if desired. Most through water systems have a Push To Talk (PTT) system, so that high power is only used to transmit the signal when the diver has something to say. For commercial diving applications this is a disadvantage, in that the supervisor can not monitor the condition of the divers by hearing them breathe.

Dry bells may have a through water communication system fitted as a backup.[3]

Voice communication protocol

Underwater voice communication protocol is like radio communication protocol. The parties take turns to speak, use clear, short sentences, and indicate when they have finished, and whether a response is expected. Like radio, this is done to ensure that the message has a fair chance of being understood, and the speaker is not interrupted. When more than one recipient is possible, the caller will also identify the desired recipient by a call up message, and will also usually identify him/herself.

The surface caller should also give the diver a chance to temporarily suspend or slow down breathing, as breathing noise is often so loud that the message can not be heard over it.

Hand signals

A diver giving the signal for cramping

Hand signals are a form of sign system used by scuba divers to communicate when underwater. Hand signals are available whenever divers can see each other, and some can also be used in poor visibility if in close proximity, when the recipient can feel the shape of the signaller's hand and thereby identify the signal being given. Hand signals are the primary method of underwater communication for recreational scuba divers, and are also in general use by professional divers, usually as a secondary method.

RSTC hand signals

The Recreational Scuba Training Council agencies have recognised a standardised set of hand signals intended for universal use, which are taught to diving students early in their entry level diving courses.[4] These hand signals provide the following information:

  1. ^ "Dive Links". Retrieved 2009-04-14. 
  2. ^ "Underwater Signals - UKDivers.net". Retrieved 2009-04-14. 

Other commonly used hand signals and variations

Diving signals sometimes differ between groups of divers. Some variations include:

Divers sometimes invent local signals for local situations, often to point out local wildlife. For example:

Instructor signals:

Torch / flashlight signals

The focused beam of a torch can be used for basic signalling as well.

Normally a diver does not shine a torch / flashlight in another diver's eyes but directs the beam to his or her own hand signal.

Rope signals

These are generally used in conditions of low visibility where a diver is connected to another person, either another diver or a tender on the surface, by a rope. These date back to the time of the use of Standard diving dress. Some of these signals, or pre-arranged variants, can be used with a surface marker buoy. The diver pulls down on the buoy line to make the buoy bob in an equivalent pattern to the rope signal.

The British Sub-Aqua Club rope signals are

Public Safety Divers

Public safety divers and many recreational divers use the following line signals while conducting circular and arc searches underwater.

Tender to diver

Diver to tender

Commercial diving rope signals

Rope signals used in the UK[7] and South Africa include the following:

Signals are combinations of pulls and bells, A pull is a relatively long steady tension on the line. Bells are always given in pairs, or pairs followed by the remaining odd bell. They are short tugs, and a pair is separated by a short interval, with a longer interval to the next pair or the single bell. The technique and nomenclature derive from the customary sounding of the ships bell every half-hour during the watches, which is also performed in pairs, with the odd bell last. One bell is not used as a diving signal as it is difficult to distinguish it from a jerk caused by temporarily snagging the line.

Attendant to diver:

General signals:

Direction signals:

Diver to attendant:

General signals:

Working signals:

Cave line markers

Line Arrow Marker
Line Arrow Marker
Arrow, cookie and rectangular line markers
Cave diving line markers (Arrow directional marker, Cookie and Rectangular non-directional markers)securely attached to line

Cave arrows, Line arrows or Dorff markers (after Lewis Holtzendorff). These are plastic arrowhead markers which are hooked onto a cave line by wrapping the line around the arrow through the slots. They are used to indicate the direction to the exit, and can be identified by feel. The message is simple, but of critical importance, as if a diver does not know which way to go at a line junction there is a risk of serious trouble. Line arrows are used at a junction on the permanent line, and at a tie-off, so when the diver gets back to the tie-off, he or she can identify which way to turn.

Non-directional personal line markers to indicate the identity of a diver who has passed along the line and has not yet returned to that point. They are attached to the line in the same way as cave arrows, and are deployed on the way into the cave, usually at critical points such as forks or jumps, and are used to indicate to other divers that someone is further in along the line. They are marked to identify the diver, and are recovered by the diver on the way out. Cookies (round markers), Rectangular markers and clothes pegs are used for this purpose. The round and rectangular markers are attached to the line in the same way as arrows, and may be personalised in any way that the users can easily recognise. Colour is often used, but as there are a limited number of standard colours available, and they are often poorly distinguishable in the dark, modifications to shape may be used which can be recognised by touch.

Miscellaneous emergency signals

A diver who has deployed a Delayed Surface Marker Buoy (DSMB) at the end of a dive may use a pre-arranged colour code to indicate if there is a problem. In some circles a yellow DSMB is considered an emergency signal, and red means OK. In most circles a second DSMB deployed on the same line will indicate a problem. A DSMB can also be used to carry up a slate with a message, but this is unlikely to be noticed unless a special arrangement has been made.

Diver down signals

Flags

Light and shape signals

A vessel restricted in her ability to manoeuvre, except a vessel engaged in mine-clearance operations, shall exhibit:

  1. three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;
  2. three Day shapes in a vertical line where they can best be seen. The highest and lowest of these shapes shall be balls and the middle one a diamond;
  3. when making way through the water, a masthead light or lights, sidelights and a sternlight, in addition to the lights prescribed in sub-paragraph 1;
  4. when at anchor, in addition to the lights or shapes prescribed in sub-paragraphs 1 and 2, the light, lights or shape prescribed in Rule 30.

A vessel engaged in dredging or underwater operations, when restricted in her ability to manoeuvre, shall exhibit the lights and shapes prescribed in sub-paragraphs (1, 2 and 3 above) of this Rule and shall in addition, when an obstruction exists, exhibit:

  1. two all-round red lights or two balls in a vertical line to indicate the side on which the obstruction exists;
  2. two all-round green lights or two diamonds in a vertical line to indicate the side on which another vessel may pass;
  3. when at anchor, the lights or shapes prescribed in this paragraph instead of the lights or shape prescribed in Rule 30.

Whenever the size of a vessel engaged in diving operations makes it impracticable to exhibit all lights and shapes prescribed in paragraph (above) of this Rule, the following shall be exhibited:

  1. three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;
  2. a rigid replica of the International Code flag "A" not less than 1 metre (3.3 ft) in height. Measures shall be taken to ensure its all-round visibility.

Surface marker buoys

Main article: Surface marker buoy

Permanently buoyant or inflatable surface marker buoys may be used to identify and/or mark the presence of a diver below. These may be moored, as a shotline, and indicate the general area with divers, or tethered to one of the divers by a line, indicating the location of the group to people at the surface. This type of buoy is usually brightly coloured for visibility, and may be fitted with one of the diving flag signals.

A surface marker buoy (SMB) tethered to a diver is usually towed on a thin line attached to a reel, spool or other device which allows the diver to control the line length, so that excessive slack line can be avoided.

A deployable, or delayed surface marker buoy (DSMB) is an inflatable marker which the diver inflates while underwater and sends up at the end of a line to indicate position, and usually either that he or she is ascending, or that there is a problem. The use of a DSMB is common when divers expect to do decompression stops away from a fixed reference, or will be surfacing in an area with boat traffic, or need to indicate their position to the dive boat or surface team.

A group of moored surface marker buoys may be used to demarcate an area in which diving is taking place. This is more likely to be used by commercial, scientific or public service divers to cordon off a work or search area, or an accident or crime scene.

References

  1. ↑ Agnew, J. (2003): Scuba Diver's Travel Companion, The Globe Pequot Press, Guilford, CT, ISBN 0-7627-2668-7
  2. ↑ "UDI Dive Computer Can Send Underwater Text Messages". Retrieved 2013-08-27
  3. ↑ The Diving Supervisor’s Manual, First edition, 2000. The International Marine Contractors Association, London. www.imca-int.com ISBN 1-903513-00-6
  4. ↑ Recreational Scuba Training Council, (2005), Common Hand Signals for Recreational Scuba Diving, Recreational Scuba Training Council, Inc, Jacksonville, FL. http://www.angelfire.com/nj4/divers/CommonHandSignalsforScubaDiving.pdf
  5. ↑
  6. 1 2 3 4 5
  7. ↑ Larn, R and Whistler, R. (1993): Commercial Diving Manual, David & Charles, Newton Abbott, ISBN 0-7153-0100-4
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