In the last decade, diving equipment has developed at an astonishing rate. These advances have made diving easier, more efficient and safer. One of the pieces that has truly enhanced our ability to stay underwater more efficiently is the dive computer. These incredible devices offer divers a whole new dimension in freedom by allowing them to use multi-level techniques.
The primary difference between a dive table and a dive computer is relatively simple. The tables are static, using only maximum depth and dive time for the calculation of decompression status. In contrast, computers are dynamic, making active adjustments during a dive. They continually track and calculate theoretical nitrogen uptake and its elimination based upon the actual dive profile. This is a big advantage because the computer takes into account the decrease in pressure as a diver ascends to shallower depths. The use of computers is rapidly replacing the use of the tables. Listed below are six reasons why all divers should be using a computer as opposed to a table.
1. Constant Tracking of Decompression Status
The purpose of computers is to help divers avoid decompression sickness. They are based upon the same or similar theories dive tables are based upon. Both the tables and computers are systems for tracking the theoretical up-take (in-gasing) and elimination (out-gasing) of nitrogen within a diver’s body. Computers, however, track constantly, throughout the changing depths of the dive.
2. More Time Underwater with Multi-level Diving Techniques
Computers allow divers to have more time underwater on multi-level dives. As an example, a dive with a computer on the wreck of the Duane in Key Largo, Florida, had a maximum depth of 122 feet and a bottom time of 31 minutes. A diver using the tables and the same profile would have been limited to a maximum underwater time of 10 minutes because the entire dive would have been computed as being at 122 feet. The dive computer allowed a much longer dive when a multi-level approach was used because it took into account that the majority of the dive was spent much shallower.
3. Accurate Depth/Time Recordings
One of the greatest challenges facing a diver is the accurate determination of maximum depth and bottom time. The actual depth and time of a dive are often recorded inaccurately. These inaccuracies make any dive table calculations faulty. Dive computers eliminate this concern because they maintain an accurate record of both maximum depth and dive time.
4. Decompression Status Made Simple—No More Dive Table Errors
Many divers have difficulty remembering how to use dive tables. Dive computers perform all of the calculations automatically with respect to decompression status. During a dive, the computer constantly tracks depth, dive time and nodecompression time remaining. Most computers will even calculate decompression time and ceiling depth should a diver accidentally end up in a decompression situation. At the surface, the computer keeps track of the surface interval and automatically calculates a diver’s adjusted nodecompression limits. These calculations are all done automatically and are continuously based upon a diver’s actual profile.
5. Ascent Rate Indicators
All divers are taught to ascend slowly and never exceed the maximum ascent rate prescribed by their respective dive tables. These ascent rates vary, but the range tends to be between 30 and 60 feet per minute. Exceeding the proper ascent rate may increase the likelihood of decompression sickness. Unfortunately, no table in the world can help determine the actual rate of ascent during a dive. All dive computers feature ascent rate monitors or warning devices that allow a diver to monitor his or her ascent and avoid ascending too rapidly. This is an incredible safety feature that can greatly enhance dive safety.
6. Air Integrated Computers Offer a Further Advantage
Air integrated computers offer divers an added dimension. They not only provide accurate information with respect to depth, time and decompression status, but accurate cylinder pressure and air time remaining information, as well. The air time remaining is based upon a diver’s air consumption rate, cylinder size or capacity and depth. It is difficult for most novice divers and even some veteran divers to accurately estimate how long their air supply will last at different depths and under various diving conditions. The following is an analogy that exemplifies this concept. Most of us are very familiar with how many miles we can drive in our car with a full tank of gasoline. For instance, I drive a sport utility vehicle and, through experience, have found I can drive at least 360 miles on a full tank of gas. When I have one-quarter tank of gas, I know I can travel another 90 miles. In contrast to our cars, most of us are unfamiliar with the fuel capabilities of a rental car. Owing to this lack of familiarity, it is difficult to know how far or long you can drive on a full tank or one-quarter tank of gas. When using a rental car, there is always an uncertainty or lack of confidence about the distance and duration one can drive. This occurs even though the fuel gauges in our cars are similar to those of rental cars.
The submersible pressure gauge (SPG) presents divers with a similar dilemma. An SPG does not offer information as to how long a diver’s air supply will last at various depths, when using different types or sizes of cylinders or under different diving conditions, such as strong currents or deeper diving. Variations in these factors can have tremendous effects on the length of time an cylinder will last.
The modern generation of air integrated dive computers provides accurate information as to exactly how much time a diver has left underwater based upon depth, air supply remaining and diving conditions. This information can serve as a tremendous aid in preventing out of air emergencies and thus enhances diver safety.
Remember that proper training is paramount to getting the most out of your computer and to diving safely. For complete information and instruction in how to improve your diving through the use of a computer, see your professional dive retailer.
On a final note, it is common, even for experienced divers, to forget how to use the tables when they haven’t been diving for awhile. Using a computer helps eliminate this problem and makes getting back into the sport easy. It is important to remember, however, that a dive computer is an awesome tool that must be used conservatively, wisely and properly.