We need some information while we are underwater. The most two important information we have to know are:
- Depth of the dive
- Length of the dive
Why do we need these information?
These two are learnt in entry level of all dive agencies (systems). The answer is not one-sentence-long but if I sum up;
Divers need to know :
- Amount of nitrogen they are absorbing
- Time exposed to that amount of nitrogen
There are certain limits for divers. Dive computers’ algorithm is designed to calculate these limits.
Let’s illustrate this a little bit. I have a Mares Nemo Sport dive computer. According to its algorithm, a diver can stay in 21 meters for 35 minutes. After 35 minutes, it becomes dangerous (decompression sickness may occur).
Dive computers calculate every step of us. It displays current depth, dive time and best of all, it tells us how long can we stay at that current depth without any risk.
Yes, you can dive without a dive computer. If you have a timer (to know thebottom time) and a depth gauge (you already have that in your console), you may calculate something by using a dive table. In SSI Dive Table, you can stay 50 minutes in 18 meters. As long as you watch your depth gauge and timer and turn back to the surface before 50 minutes, everything is cool.
However, dive computers are great, because it not only shows information about the dive. Other features include dive logging (dive computers saves up to 1000 dives), PC mode (you can watch your dive profile from your PC), thermometer, safety stop 3 minute count down, warning when the ascent speed rate violated even a digital compass to easily navigate.
A dive computer is you. It calculates dive you have done in the morning, amount of nitrogen in your blood, surface time you had and amount of nitrogen you sent away by breathing. It makes its calculation in your second dive by using these parameters.
Most importantly, a dive computer gives you the chance for a longer bottom time and less surface time. That’s because:
When you use a dive table to get the information for the maximum bottom time to 30 meters, you’ll find that it is 20 minutes (SSI Dive Table). The table “thinks” that you’ll directly reach bottom, hang around and turn back to surface directly.
However, this is often not the case. Divers generally jump from the boat and first descend to (for example) 5 meters. Every diver make the final checks, leader gets the “okaayss” from every one of them. Then they go on a little bit, arrive to 15 meters, leader asks the air pressure in divers’ tanks.. They reach 20+ meters, search a cave for a moray-eel with their torch and etc.
There is a huge amount of nitrogen difference between descending directly to 30 meters (like the dive tables suppose we do) and a multi-level descent to 30 meters (dive computers calculate). Because the ambient pressure is different in every level.
A dive computer will supply all the information you need underwater. You’ll join your dives while raising your safety with dive computers.
Watch style: You can also use them as a watch. On the land, they display date and time just like your on your wrist right now.
Computer style: A little bit large. Has large numbers displayed on it, easy to read. On the land, screen doesn’t display anything.
What I advise you about buying a dive computer is to buy:
- A dive computer that has features you need. If you are using nitrox, you should buy a dive computer that also has nitrox algorithm. On the other hand, don’t buy a dive computer with trimix features if you are not even planning to experience a gas mix dive in your dive career. This will only raise the price of the dive computer and you’ll be paying for features that you are not going to use.