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Things to Do While Diving and What You Need to Do Them

The Gearmeister continues his activity-oriented musings with this month’s column on dive lights, also known as “torches” in many parts of the world.

 

 

 

An illuminating subject

There’s really no difference diving at night than in the daytime - except that it’s dark. (And it’s not always dark. On a white sand bottom with a big moon, it can be a delight to cruise around under the natural light.) There are also lots of sea creatures hanging out that you won’t see during the daytime. For example, you’re much more likely to see an octopus at night than during the day. And even if you think you’ll never dive at night (eventually you will), a light is good for day dives in deeper water and exploring under ledges and looking in crevices on the reef.

So, let’s take a look at the hundreds of choices available to you when you’re looking for a dive light.

But first, let's review the Gearmeister’s Rule Number One: "If I spend more than $10 on something, it goes on a lanyard." And rest assured, you will spend more than that on a dive light. So, hang on to it! For a primary light, I like a big coil lanyard attached to my BCD. For my secondary light, a wrist lanyard does the trick. Trust me, it is definitely a drag to watch your $200 light disappear into the depths below.

 

The right light for the job

The first thing to think about is what you want to do with the light. Dive lights can generally be divided into four functional groups:

Primary lights - these tend to be larger with a brighter and wider beam. But that extra beam brightness usually requires more power= more batteries = more bulk.

Secondary lights - serve as your backup light on night dives in case your primary light malfunctions. These lights are usually small enough to keep in a BCD pocket and have a shorter range and narrower beam than a primary light. 

Pocket lights - these lights are small enough to carry in your BCD pocket and are made for exploring during the day. In spite of their small size, the beam can be just as bright as many primary lights.

Tank lights and personal marker lights - are used to make a diver more visible so buddies can stay together. They come in a variety of colors, so I usually give each buddy pair a different color while the divemasters leading a night dive get their own distinct color. This makes it easier for everyone to find their buddy and for the group to know who to follow. I often use chemical lights, commonly known as Cyalume, which have a burn time of eight to twelve hours. Tie them to the cylinder valve and you have instant organization for a group night dive.

For night diving, most divers use all three types of lights - a big primary, a smaller secondary, and a marker light. Some divers also use a specialty light such as a strobe light or omni-directional light to mark the anchor line or exit point.

Also, don’t forget to look at the depth rating. While most lights are rated to well below recreational dive limits, it pays to read the box. Most lights are made of some sort of plastic while a few are made of aluminum. As long as the depth rating meets your needs, the material is just a matter of personal preference and wallet size.

Light beams and burn times

In evaluating dive lights, the inevitable questions are “how bright is it?” and “how long does it last?” You should also be asking “how wide is the beam?” Unfortunately, none of those questions are easy to answer since they all are largely a function of the type of bulb and the power source.

Dive light technology has advanced rapidly in the last couple of years. It wasn’t long ago that we had only incandescent bulbs. These gave off a sickly yellowish light, weren’t very bright unless hooked to a large amount of batteries, and didn’t last all that long. The answer to these drawbacks was the halogen bulb which burned hot, bright, and white (but required a lot of power.)

Next, we saw LED lights which were virtually unbreakable, lasted a long time, gave a natural white light, and used very little power. Unfortunately, the beam was pretty weak. About the same time, we got the HID (High Intensity Discharge) light. These lights were bright and pretty long lasting, but ate a lot of power.

Now, technology has given us bright and broad LED beams almost doing away with the other types. And HID lights have virtually replaced halogen lights as the brightest lights in the business although they are now mainly used in specialty applications where a bright narrow beam is desired and carrying lots of batteries isn’t a problem.

As for the power supply, batteries are batteries. Sort of. Some lights use regular disposable or rechargeable batteries in AA, C, or D-cell size and anywhere from two to eight batteries in a light. Other lights have a rechargeable power pack which may be attached to the light or connected to the light head by a wire.

Narrow or wide?

Light beams can also be described as narrow or wide. Narrow beams tend to be more focused and brighter within that area, which is nice for looking in crevices. Wider beams may not be as bright, but cover a broader area, which is nice for general night diving. When evaluating a light, look at the beam and find the “hot spot”, the brightest area of the beam which is ideally located in the center of the beam. From there, notice how far out the beam extends. There may be usable light in this “halo” well away from the center of the beam. Then check for dead zones in the beam. Too many or too big could be annoying.

Carrying it around

Most secondary and pocket lights are a baton-style so they can fit in your BCD pocket. Tank lights are small and attach to the cylinder. But your primary light gives you more choices. Most lights are a little bit negatively buoyant, so it pays to carry that light around in the store for a few minutes to get a feel for how easy it is to carry and point while diving. The most common handle is the pistol grip with the handle under the light which makes it easy to point and carry. The second most common is now the lantern-style with the handle on top, which I find a little more difficult to point, but easy to carry. Then you can get a little more esoteric and get a headlamp-style which keeps your hands free but limits your flexibility in looking around. And finally, you can get a wrist/hand mount with the power pack remotely mounted, although this has become pretty specialized for wreck and cave diving.

Making it all work

A big thing in the usefulness of a dive light is how easy it is to use. In addition to carrying it around, you need to be able to turn it on and off, and that means with one hand or two. In my mind, one hand is better, especially for the primary. Some people worry that the switch mechanism is a leak waiting to happen. In all but the lowest quality lights, modern technology has made this unlikely. Lights requiring two hands to operate typically turn on and off by tightening or loosening the light head, which is also the battery compartment access. Although, this is sealed with an o-ring, loosening it just a little too much when turning it off can result in a flooded light.

For one-handed operation, make sure you can operate the on/off/intensity switch easily with one hand. Many lights also have some sort of switch locking mechanism to prevent your light from accidently being turned on or off. Make sure you can also operate this with one hand. You would hate to have to let go of an anchor line in a stiff current just to turn your light on.

You can be a little less picky with your secondary light since you may need both hands just to get it out of your BCD pocket. Ideally, one hand operation is still better than two.

Enlightenment

This should give you a few things to think about in relation to night diving or just exploring around the reef. A good dive light can make it all a lot more fun and relaxing.