Dive Computers Buying Guide

Dive Computers Buying Guide

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Dive Computer

Why Do I Need One?

Regardless of what you may hear, you can dive without a dive computer.For years before dive computers were invented, people safely dove and enjoyed themselves immensely. That being said, are dive computers a tool that makes scuba diving navigation, decompression stop calculations, log information gather- ing, and much more a very convenient tool? ABSOLUTELY!

Dive computers should not be purchased on a whim; take the time to do some research and determine which features you need, which features you'd like, and which features you didn't know were available, Once you've done a little homework, you'll discover that there is a dive computer out there for you O¨ per- haps two or three!

Navigation

A key element to any scuba diver's gear is his/her compass. It lets you know where you're heading and how to get back to your boat or shore.

Some dive computers allow you to supplement or replace your old-fashioned compass. They offer digital displays of your heading and don't require you to have the instrument perfectly level to function properly.

Depth Gauge

Dive computers can replace or supplement your depth gauge; in addition, they can more accurately re- cord your various depths. Unless you spend every moment of your dives looking at your depth gauge, you will probably guess at some of the depths encountered during the dive, which can negatively affect your decompression stop calculations. Dive computers carefully determine how much time was spent at each depth, while allowing you to enjoy the surrounding scenery.

Dive Computer and Dive Table

Calculations

Dive computers take the math out of diving, including some potentially life-saving calculations.

One of the basic functions that dive computers offer is decompression calculations. Based on your dive's duration and depths, a dive computer will calculate how many decompression stops you need to make and at what depths. Many dive computers will perform revised decompression stops calculations should the diver inadvertently miss a deco stop or ascend before the deco stop was to end.

Some dive computers also calculate no-fly times. This is essential for divers who rely on air travel at the end if their vacations. After a dive, nitrogen slowly releases from your body, by ascending in an airplane, any remaining nitrogen in your body can expand, due to the lower pressure on your body as the plane ascends. By performing a no-fly calculation, the dive computer lets you know when you can safely fly next.

Memory

All computers offer a dive log function that allows you to review your completed dives. The number of dives logged varies by computer; before deciding upon a computer, make sure it will record enough dives at any given time.

Older dive computers only showed the most recent dive. Now, the newer models tend to retain the data for at least 10 dives.

PC Compatible

Some dive computers offer the ability to download your dive details to a personal computer. This allows you to create a permanent record of your dives and supplements the fact that many dive computers only retain the details of your 10 most recent dives.

The ability to download from your dive computer to a PC requires that you purchase software with an interface. The software will covert your dive into graphs to show the various depths achieved during a dive and the time spent at each depth. More sophisticated dive computers will also display ascent rate violations (aka missed decompression stops and rapid ascents), air consumption (if the computer is air-integrated), and the predicted nitrogen load in your tissues.

The sample to the right is a dive log after the information was downloaded from a dive computer to a PC.

Air/Nitrox Integrated

Dive Computer with air integration

A basic dive computer only monitors depth and time; this means you'll still need to use a pressure gauge and compass. If you'd like to do away with your pressure gauge, you'll want to choose an air-integrated dive computer. This option allows you to run an air hose from your tank to your computer. Air-integrated dive computers can display information such as air time remaining, bot- tom time remaining, and your tank's current PSI reading.

Non-air-integrated dive computers are less expensive, and may prove to be a good option if you already own a pressure gauge. Additionally, if your air-integrated computer experiences a glitch ( a rare occurrence) while at depth, you may lose valuable knowledge about how much air you have left.

If you decide that you want an air-integrated dive computer, it is important to decide of you will only use air or if you will use a Nitrox mix. If you currently dive using Nitrox or you think you may use Nitrox at some point, you will need a computer that allows you to program the percentage of oxygen in your mix. Nitrox-compatible computers are compatible with air-diving because they can be set to show 21% oxygen (standard compressed air); standard air dive computers cannot accommodate Nitrox. So, if you don't see yourself ever using Nitrox, choosing an air-only dive computer will ease the burden on your wallet.

Mount Style

Dive computers come in two styles: wrist mounted and boot mounted. There is no right or wrong when deciding which mounting style to purchase. This is a decision that boils down to personal preferences and which format you find to be most compatible with your current gear.

Back Lighting

The less basic dive computers offer back lighting, which allows you to see your computer's display without using your flashlight. This is a convenience feature that many divers won't go without.

Activation

There are two ways to activate a dive computer: manually or with water. Some dive computers require the diver to press a button prior to entering the water in order to display the computer's readings. Some dive computer manufacturers realized divers are notorious for forgetting to press the On/Off buttons on their dive computers. To combat that problem, some dive computers activate once they enter the water. This feature saves you from failing to capture your dive's details, but it does raise the computer's price tag amount.

Dive Computer Accessories:

  • Battery

    Spare Batteries

    Without batteries, your dive computer becomes a useless piece of gear. Keep spare batteries on hand at all times, so your dive is as safe as possible and can be recorded for post-dive reviews.

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  • Computer Console Clip

    Console Clip

    Keep your boot-mounted dive computer close at hand. Console clips allow you to attach your console boot to a D-ring on your BCD; this saves you from hunting around for your computer and very important data.

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  • Save-a-Dive Kit

    Save-a-Dive Kit

    The last thing you want to do is find out on the beach or dive boat that something is wrong with your gear, and not have a way to fix the problem. By carrying a save-a-dive kit, you can still safely enjoy your dive or snorkeling adventure just like you planned.

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