Dive Computers - The Most Important Functions and Features

Modern dive computers are complex devices with so many functions and features that sorting them all out can get downright dizzying. But that’s only the initial impression. Once you go through the owner’s manual and set the basic parameters — feet or meters, Fahrenheit or Celsius, perhaps time and date — you probably won’t have to mess with those again. So that only leaves the functions that may change from dive to dive, which are actually the most important.

1. Select Your Algorithm
If you happen to own a dive computer that lets you do this, consider yourself lucky, because this can be a valuable function. What you get is a choice between diving with a liberal algorithm or a conservative algorithm. The algorithm you choose may change from day to day based on how rigorous the diving conditions are or how you might feel physically. This function is also useful when you want to choose the algorithm that most closely matches your dive buddy’s computer, so you can dive with similar computations for no-decompression limits (NDLs) and bottom time, thereby allowing you both to follow the same profile without one having to break off and surface early.

2. Set the Conservative Factor
Virtually all dive computers provide a way to set or factor in a level of conservatism for your dive. Once again, this is something that may change from day to day due to both external and internal conditions. Most computers offer ways to actually program in levels of conservatism by employing specific conservative factor settings, personal settings or altitude settings. Computers that don’t offer a programming function usually have bar graphs that enable you to build in a safety factor by backing off on the NDL loading pixels. Or, you can always refer to the No-Deco countdown and mentally subtract, say, 10 minutes from the NDL reading when you’re in 60 to 100 feet of water, or three minutes when you’re deeper than 100 feet. Either way, the goal is to program in or prepare for whatever game plan you’ve chosen before hitting the water.

3. Set to Air or Nitrox
Virtually all recreational diving is done on air or 32 percent nitrox or 36 percent nitrox. Many divers will alternate between air and nitrox depending on their dive trip, dive day or dive profile. Also, most computers have a default mode for nitrox settings that kick in after 24 hours, so even if you dive 32 percent nitrox all the time, you still need to double check your nitrox setting before your giant-stride to make sure your computer and your cylinder are on the same page.

4. Set Alarms (Max Depth, Tank Pressure, Turn-Around)
Some divers like audible alarms and some prefer visual alarms, but no matter your preference, remember that spending time in an inherently hazardous environment — with so many fish to admire, bat rays to chase and corals to photograph — can be extremely distracting. You really need effective ways to remind yourself to check your air, depth, bottom time and NDLs. Setting a maximum depth alarm is good practice in general but critical if you’re diving nitrox. Inching close to remaining bottom time is another good reason for sounding an alarm, as is air time remaining if you’re diving with an air integrated computer. Programming alarms during your pre-dive ritual is all part of planning your dive and diving your plan.

5. Set Safety Stop and Deep Stop Parameters
On some computers, safety-stop settings are pre-programmed and therefore automatic. Other computers let you do your own programming. A standard safety stop is three minutes at 15 to 20 feet. Some divers who know they’re going to be pushing the limits will program in a five-minute stop just for good measure. Some computers also offer a deep stop function. The controversy continues as to whether the deep stop is actually a safety benefit. Some experts say if your computer offers it, then use it. Other experts say deep stops are not helpful so don’t bother. Virtually all deep stop functions can be disabled, so you have the option of using it or not using it.

2017 Gear Buyers Guide: New Dive Computers