DevonDiver
N/A
I teach technical wreck (not cave, yet), but the issue of restrictions and confined spaces exists in both. On those courses, I have students in both sidemount and backmount configurations. What I see, as an instructor, is that the sidemount configured student divers enjoy considerably less stress when moving through confined areas. Not just 'small restrictions', but more generally in the overhead environment.
Of course, unlike Ragnar, I don't have the luxury of only diving 'upright' wrecks - so passages, doors, hatches etc may present themselves at all angles. Some wrecks, especially Japanese, have much smaller doors/passages. The sidemount diver can maneuver through those areas, altering their trim as necessary. They can jack-knife, twist and flex to fit around any corner, pass obstructions or fit through any shape of restriction - more often than not without even needed to make use of their capacity to partially disengage and swing forwards their cylinders.
The backmount diver is very limited in that capability and I see, first-hand, much more struggling. I also see, or rather hear, plenty of valves clanging loudly against structure...
What I describe above isn't passage through extreme restrictions - it's generally moving around passageway/decks inside the wrecks. There are vast areas inside the wrecks I dive that are wide open to sidemount divers, but remain impassable, or highly advanced, for backmount divers.
With regards to diver safety - well, a sidemount diver has the option to exit the wreck in an emergency though smaller areas. In the same circumstances, a backmount diver could be trapped... and could die. I like that sidemount gives me more options to escape a wreck, should that ever be necessary.
(ok a bit much..., 'normal', at least)
