Light Sources For A Night Dive
Different Types And Uses Of Light When Scuba Diving At Night
Jul 20, 2008
At night it is never completely dark underwater. There are diver’s torch light, moonlight and even light from certain fish.
Most night dives are planned to start just before sunset or just before sunrise. This allows the entry (or exit) to be done with some ambient light. Diving on the full moon can sometimes provide enough light for exit and entry.
Light on Every Diver
A light source should be on the tank on every diver. This allows Divemasters and lookouts to easily see every diver. There are a range of lights available for this purpose: flashing strobes, small circular lights and chemical light-sticks
However, when facing another diver the light will be hidden. This is especially important on the surface after ascending and a lookout on the boat or shore is trying to see a tiny spec of light in the vast ocean. Swimming on the surface should be done backwards to ensure the lookout can see all divers.
Chemical Light Sticks
Chemical light sticks are small plastic sticks filled with a solution and a smaller glass vial inside. Bending the outer stick breaks the inner vial and mixes the two chemicals. The chemical reaction provides light for hours.
These should be connected to the regulator’s first stage yoke with string or a rubber band. Some divers put them between the screw down nut and the back of the valve. This is not good as the regulator was never designed to have a piece of plastic between it and the valve stem.
Also, with string or a rubber band the stick can be removed if required as a back-up light
Dive Torches
Dive torches range from cheap models providing adequate light to expensive ones that turn night into day. A torch should be easy to use and suitable for the type of diving. A sportdiver may not need a strong, powerful torch, but an Instructor or Divemaster may need the large luminescence when diving with a group.
Batteries should have enough charge to last the dive.
Spare Light Sources
A spare light source should be taken on each night dive. This could be a dedicated second torch, or a chemical light stick that can be activated if required. There are many small torches around that easily fit into a buoyancy compensator jacket. These can come in handy during daylight diving for looking under ledges and into small caves.
Flooding Dive Torches
A dive torch will be under pressure when on a dive, so will have ‘O’ rings to provide the seal. Because of this, there is a chance of the torch flooding during the dive. The ‘O’ rings should be checked to ensure they are free of sand or grit, have no cracks and are sealing properly.
If a torch is flooded, it should be opened as soon as possible after surfacing. In some situations, the torch may flood and become difficult to undo on the surface because of the pressure difference. If left too long the salt water inside could react with the batteries giving off gas and building up pressure eventually leading to the torch exploding. This has occured.
Some of the cheaper torches should not be turned off underwater. Some models use the screw top as the switch and can easily flood as the ‘O’ ring seal is disturbed at the same time.
Careful consideration to the use of underwater light sources are vital on a night dive. The right combination, care and maintenance are all important to ensure night diving is safe and enjoyable.
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