7.2.1.1.1   Conditions for 3-man Crews

A dive team of three, consisting of a diver, a supervisor, and a stand-by diver, is acceptable where the diving supervisor has signed off on a Job Hazard Analysis (risk assessment) stating that there is:

a)     good visibility in the water;

b)     no danger to the diver from natural currents or currents associated with weirs, dams, sluices, locks, outlets, or inlets in the vicinity of the workplace;

c)     no risk of entrapment or entanglement of the diver; and

assistance from an additional person, acceptable to the dive supervisor, readily available in case of an emergency.

Scuba Diving:

6.5  Minimum Crew

6.5.1
A minimum crew of three workers shall be present on each dive site on which diving will
(a) not exceed 18 m (60 ft) in depth;
(b) remain within the no-decompression limit; and
(c) be conducted in a location where it is known that no hazard of entrapment exists.

6.5.2
When using the buddy system, a minimum of two divers must be present in the water, and a third person must stay on the surface to act as a supervisor/tender. This person on the surface shall be a competent supervisor as specified in CSA Z275.4.

6.5.3
When using lifelines, floats or audio communication with the surface,
(a) a standby diver and a supervisor/tender must be on the surface; and
(b) each tender shall tend only one SCUBA diver unless the divers are on floats, or have lifelines and effective 3-way voice communication, in which case each tender may tend two divers.

6.5.4
When a dive does not meet the requirements of Clause 6.5.1, then
(a) a standby diver and a supervisor/tender shall be present on the surface; and
(b) if not using the buddy system, at least one diver must be tethered and carry a bailout bottle.