Fully agree with your views regarding wrist mounted computers, especially for depth in commercial diving, Francis and the IMCA statement in D 033, although referencing SCUBA divers is very clear; "Some SCUBA divers wear decompression ‘computers’ but these are programmed for recreational users and may not be reliable for the heavier types of work normally carried out by commercial divers." NORSOK also have a similar statement. When we look at Lewis case in detail, it is clear that the supervisor was relying upon the depth readings for Lewis by infrequent and intermittent pneumo checks, (Lewis did not have a wrist device) whereas for Diver 2, he was using the wrist computer, this can be clearly seen on the BB video, this was how the supervisor managed to not see that Lewis had dropped down to slightly deeper than diver 2 when he went to his assistance, on the incident dive, supervisor did not pneumo Lewis at his deeper depth, as a consequence, Lewis dive was given a 18.3m Deco profile and Diver 2 a 21.3m Deco profile when in reality, for good dive management, the dive should have been treated as a single dive for both based upon maximum depths and bottom times.