Purpose: To provide illumination in the event of a primary lighting system failure
Benefit: Provides a degree of redundancy that increases the safety factor of a dive
What to look for:
How to fit:
Two backup lights should be carried. Each light should have a half-inch bolt snap affixed to it with cave line. The bolt snap is used to clip the light to the chest D-rings. The body of the light is held in place by being captured by a strip of bicycle inner tube on the harness. Backup lights are never stowed in a pocket, as accidental activation would go unnoticed. With its placement on the harness, accidental activation would be noticed by other divers in the team.
Unfortunately, back up lights are often overlooked and neglected. Because of this, the back up light must be rugged and durable. This piece of equipment, though often not used, is a critical piece of equipment. When the backup light is needed, it’s due to a failure of the primary light and the back up is needed in order to exit the overhead, or on the ascent. Having a non-functioning back up light could bring serious consequences. For that very reason, it’s critical that the diver take care to check the back up prior to every dive and replace batteries and bulbs as needed.
Recommended Burn Times
Under no circumstances should any dive be started using lights with anything less than twice burn time of the planned bottom time. For example, if the planned dive time is one hour, each diver should have two hours of burn capacity between the primary light and back up lights. This provides 100% redundancy.