ADCI Safety – Jan 9, 2009

ADCI Industry Update #2009-01 January/2009
TO:  ADCI General Membership and Industry Stakeholders

The following items of information are provided to bring your attention to recent industry developments, initiatives, or safety notices.  If you do not wish to receive future Industry Updates, please use the unsubscribe option, located at the bottom of this update.

Dive Flags / Alpha Flags / Day Shapes

This ADCI Industry Update and Safety Reminder is to inform stakeholders of the importance displaying the proper Diving Lights, Day Shapes, and Flags when conducting operations off of a vessel.  International Regulations for Preventing Collisions at Sea- Rules 3(a), 27(b), 27(d), 27(e), 27(g), and 30.

Vessels are defined to include every description of water craft including non-displacement craft and sea planes used or capable of being used as a means of transportation on water.

1. The Regulations require that all vessels engaged in dredging or underwater operations, when restricted ability to maneuver, should exhibit lights and shapes as follows:

  • Three all around lights in a vertical line where they can best be seen.  The highest and lowest of these lights should be red and the middle light should be white.
  • Three shapes in a vertical line where they can best be seen.  The highest and lowest of these shapes should be balls and the middle one diamond.  The shapes should be colored black.

2. If a vessel is engaged in dredging or underwater operations and is making way through the water, then masthead lights, sidelights, and a stern light are required in addition to the lights required in paragraph 1.

3. If a vessel engaged in dredging or underwater operations is at anchor, then in addition to the light(s) or shape(s) required for vessels at anchor or aground, it should displayed the lights or shapes required in paragraph 1.  If an obstruction exists, then in addition the vessel should exhibit:

  • Two all round red lights or two balls in a vertical line to indicate the side on which the obstruction exists.
  • Two all round green lights or diamonds in a vertical line to indicate the side on which another vessel may pass.

4.  If the size of the vessel engaged in diving operations makes it impracticable to exhibit the shapes described above then a rigid replica of the International Code Flag ‘A’ not less than 1 meter in height should be exhibited and so displayed that it can be seen from all directions.

5.  Vessels of less than 7 meters in length are not required to exhibit the diving lights as described above.

6.  The interpretation of the regulations makes it mandatory for all vessels to comply with them.  The only offshore installations not so affected are permanently fixed platforms which, once they have been placed in position, are no longer vessels.  However, it may be considered prudent for fixed platforms to conform.  In addition, Installation Managers of fixed platforms should ensure that all vessels in the vicinity are warned by any means possible that divers are operating from the installation or from any smaller craft close to the installation.


  • When vessels are conducting diving operations that they display both the Alpha Flag and The Diver Down Flag.

Dive Down Flag

International Alpha Dive Flag

  • When vessels are NOT actively engaged in diving operations they should NOT display these flags.
  • Crews should monitor the serviceablity of their dive flags to ensure that they are not too worn, thus compromising their visability to other vessels in the areas.

Vessel Encroachment
Keeping a Watchful Eye

Despite the regulations and communication capabilities readily available to commercial vessels, there are many pleasure crafts that are piloted by individuals who are not familiar with International Flags, Day Shapes, and Diving Lights.  This is one of many reasons for why it is important for vessels to assign personnel to keep a vigilant watch for other vessels that may encroach upon the designated area where underwater operations are being conducted.

This Information was sent to further the communication of all industry stakeholders. Safety is the primary concern of the ADCI. Remember:  a real time Job Safety Analysis is important, but nothing can replace good common sense.


Phil Newsum
Association of Diving Contractors International


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