Sheck Exley was one of the first divers to identify a set of common cave skills that related directly to deaths or incidents underwater. One of these was the fact that cave divers should carry with them appropriate lighting. It sounds rather obvious, caves are dark… in order to see you require light. Strangely though his use of lights was a back up system (you used the line to get out, not lights) - lights helped you get out faster using less gas and in some instances with less cuts and bruises from unexpected obstacles.
The modern school of thought is that every cave diver has at least three lights, a primary and two back up lights. As far as basic characteristics goes, lights need to be:
- As bright as possible, an easy task these days.
- Uniform across a dive team, i.e all divers should have lights of approximately the same brightness. This concept is based on human physiology, so long as there is no bright light to destroy the natural adaptation, our eyes are capable of adapting to dim light conditions.
- As small as possible and neutrally buoyant (large lights get snagged on risk in narrow areas and are hard to manoeuvre with in strong currents)
- Dependable (water and pressure proof), easy to repair and maintain and with as small a failure rate as possible.
Finally, each light should also last as long as the planned dive (which is not as obvious as it sounds).
When it came to configuration of lights Sheck was not so talkative. Modern school of thought sees a primary canister light neatly stowed on the waist belt with two secondary lights stowed on the shoulder straps. Helmets make no appearance what so ever. For those of you who are not familiar with all the gadgets that come with technical diving, canister type lights have a battery in a canister (hence the name) that is connected to a light head via a umbilical. The diver holds the light head with his hand using a Goodman handle which basically attaches the light head to the top of the hand.
Using the light is not intuitive (or at least I did not find it so). In order to see you have to point your hand in the direction he is looking… something I found intensely annoying when I first moved over to this configuration - my hand would be doing something which would mean my light would be facing any direction but the one I wanted to swim in or look in.
Older divers such as myself did not grow up in a world of canister lights that provided liquid sunlight at the flick of a switch. We used normal hand held style torches and in order to accommodate high failure rates as well as light up the cave, we had to use lots of them. Which led to the interesting problem of how to practically transport them all…you only have two hands. Enter the helmet! This was the perfect solution as it could carry four, maybe six lights without using up valuable hand space. As any technical diver will tell you, diving can have quite a significant task load and not having to worry about lighting up what you are doing or where you are going makes life a whole lot simpler.
The down side of the helmet is that it can be very buddy unfriendly. It takes time and practice to not blind your buddy when casually looking in his general direction. This fact has been used to chastise most helmet divers and promote the use of the simpler canister torch with two stowed back up lights.
But, technology comes to the rescue. Just as the need to carry spans of torches has fallen away thanks to the evolution of canister lights, so has the need to have a large, bulky and heavy helmet in order to carry one (heavy) torch just to light up your immediate area. These days lights come small (the mini Q40 springs to mind, Sartek has some stunning baby lights as well). These can be easily mounted on a mask strap and because they are not killer bright, do not blind surrounding divers.
I will miss the sight of divers plunging into the darkness, small white haloes of light replacing blocking out facial recognition and whilst there are some dives (deep, task loading, where a helmet does have a place, for the rest of us, the era of the helmet is well over.
Long live liquid sunlight and canister lights!