Quote: (Originally Posted by ahar)
The two backup torch thing is mandated at the DIR F level so there has to be a reason at every level of diving, even those dives to 30m or above in open water. If two backup torches are not needed for DIR F type dives, then why make it mandatory, as one of the precepts of DIR is only taking the kit that you need along.
I would have thought if the dive is likely to use your primary light you would take at least one backup. If the dive required your primary (cave, wreck penetration, night, etc) then you would want two backups.
If you were doing an open water dive during the day with good vis you could probably justify not having two backups (there might even be a case not to bother with a backup at all unless you can see it
).
Having said that the backup torches are small and tuck neatly out of the way, so if I had two I'd be tempted to carry both :D