Should I Get A Dive Computer
By: Charles Davis
Dive Computers are a Sign of Dedication
Each diver will have to decide for themselves if a dive computer is a must have, nice to have or a waste of money. Most serious divers swear by their computers but in reality they were most likely diving for quite a while before purchasing their computer. Dive computers are relatively new in the overall scope of scuba diving and will most likely be your most expense purchase, even more than the training and basic equipment. The variety and capabilities of the different computers on the market are staggering. However, before you even start sorting through the different manufacturers and models, you really need to determine do you need one and how great is the need. You learned the dive charts in your training and they have served you well. When you plan your dive, you look up your limits and adjust your plan to ensure that you stay within the safe limits. Before your second dive, it is back to the charts to look at your residual times. When you start doing dives that are a little more difficult to plan such as a multiple level dive, then you can start using the dive wheel. However both require you to stay within the plan. Also they assume that you are at the same depth for the same amount of time that you calculated.
What is a Dive Computer
Before getting to involved with the topic, I think a brief definition should be included. While there are numerous features on different models we will stick to the basics. Technically it a very difficult process. The computer is able to take its own pressure reading and can accurately keep time. Inside the dive computer are what are referred to as compartments. The number varies by model, but they are calculations designed to mimic the effects of nitrogen on different type of tissue within your body: such as fat, muscle, tendons and so forth. Tissue types absorb and release nitrogen at different rates. Every two seconds or so the computer take a pressure reading, calculates the lapse time and updates the compartments. Using a logarithm based on dive tables it calculated and displays your NDL and other information. The computer is calculating on the performed dived not on how it was planned. Computers are not perfect, there are items that affect the absorption rate that the computers can not measure, such as your activity level, the presence of drugs or alcohol in your blood or your level of hydration. The use of a dive computer allows you to maximize your time underwater using real time data while keeping you within a safe profile.
What is Your Normal Dive
The types of dive you do will be a factor whether it is a must have, nice to have or a waste of money to get a dive computer. If you only dive infrequently and at shallow depths then a dive computer may not be necessary for you. A dive at 30 or 40 feet can easily be managed using the dive tables. If you are doing dives around 60 feet but at a single depth then there may be some use for a computer but it is still limited. If the 60 foot dive is also able to be done as a multilevel then you will see some benefits of a computer allowing a little extra dive time. It is not unusual to an additional 15 or 20 minutes to a dive that goes to 60 feet but returns to 30 feet during the dive. Once you start diving beyond 60 feet then a computer becomes a very useful tool.
If you have not used a dive computer yet, I would suggest you rent one for a few dives. Many dive centers have computers for rent. Some center are even making a computer a requirement for deep dives. Deep being defined at below 60 feet. Plan the dive as you normally would but, use the readings from the computer during the dive. Afterward compare what you were able to safely dive with the times listed in the dive plan. This should help illustrate the value of the computer for your diving style.
If you are thinking of getting a computer, project how many dives will you do in a year, also how many of those are deep dives. Also take the cost of the dive computer you are interested in and divided it by the cost to rent the computer. This will tell you how many dives it would take to pay for the computer based on the rental cost. These three number should show you the economic benefits of buying instead of renting.
Dive More Safely
Dive computers have helped many divers maximize bottom times while still staying in a safe range of risk. They are also able to warn a diver that has exceeded his NDL and to provide guidance to reduce the risk with decompression stops. Given the serious injuries that can result from DCS, a dive computer should be considered for anyone who dives near the edge of the dive tables maximum time.