A freediving computer is an important part of your freediving gear, but it is one of the last pieces of gear that you should buy. Remember, there is a big difference between freediving computers and dive computers, although there are some that combine both.
When purchasing a freediving computer, it is important to get one that has a specific freediving mode, not just a gauge mode. This is important because it will keep track of other parts of your dive, not just the down time and the depth.
You want to look for one that keeps track of your surface interval time. This is important because it is possible for freedivers to experience the bends just as those who scuba dive. Freedivers follow a different protocol to avoid the bends. They obviously cannot take a long time to make their ascent; so one way to avoid the bends is for a freediver to spend more time at the surface. The freediving computer can keep track of this surface time, so you can focus on other things.
Freediving computers also keep track of your maximum depth during a dive and your bottom time so you can record and make improvements.
Some are equipped with alarms so if you are trying to reach certain depths you can set an alarm for that. During competitive dives, Erin sets an alarm to let her know if she has reached the depth that she wanted to when her alarm sounds to keep her on track.
They can also keep track of your dives with a graph. This is a specific function on some freedive computers. On Erin’s Suunto D4 and the new D4i, it can keep track of your dives with a graph and it has an easy interface. It keeps track of your dive moment to moment. It takes samples of your dive every second or so and what you can see at the end of your dive that the computer has recorded your dive in its memory. This allows you to make evaluations and then are able to see how efficient your dive was and if you were less efficient on the descent or ascent and where you need to make improvements.
There are many freediving computers, but not all have such an easy interface. The Aires F11 offers many additional functions, but the interface can be a bit confusing to some and may require more time to master. Some believe it is worth the extra time learning about the computer for what it has to offer.
Cressi makes a dive computer and the Omer MIK1 is a nice freedive computer as well. The Suunto D4 just happens to be Erin’s favorite.