Sunday, January 10, 2010

Air/nitrox: double your pleasure. (dive computer). USA, LLC

oscillate between two worlds, originally uploaded by Hersi-M.

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After I was certified for nitrox, I remember thinking, "Jeez, now I have to buy a new dive computer. How much is that gonna cost me?" I am, you see, cheap. I'd like to be able to use my current dive computer until it biodegrades (like the rest of my gear). Only then will I feel I have gotten my money's worth out of it. Well, Undersea Breathing Systems (UBS) has helped make my life and yours, potentially simpler. The Chameleon dive computer can be upgraded from a strictly air-based computer to a full featured nitrox computer while you wait at a your local dive shop. It's that easy. Buy one computer and you're set for nitrox or air, until it biodegrades. It makes for a very simple, sensible and hassle free decision when looking for a dive computer. Oh, and there is more good news - the Chameleon is inexpensive, too.


As a nice safety measure, when the Chameleon is configured exclusively for air, it can't access the nitrox programs. But that doesn't mean it lacks features. In fact, it packs them in. During the dive the screen displays only the necessary information needed for the dive - bottom time, current depth/maximum depth, water temperature and no decompression time remaining. During the ascent the screen changes slightly to accommodate a safety stop. Above 20 feet a 180 second (three minute) countdown appears for the safety stop. This is actually a clever feature, as time seems to go by little quicker if you're watching seconds tick off instead of minutes. If you enter a decompression situation, the computer switches over to a ceiling depth decompression principle. What this does is gives the diver a depth ceiling (the shallowest a diver is allowed to ascend) and a total ascent time to surface.

The Chameleon also offers a nice bit of personal adjustability. Alarms or warnings can be set for audio or visual. The alarms/warnings run the gamut from an ascent rate warning, safety stop alarm (do safety stop) and a begin ascent alarm (no decompression stop time reaches zero), to decompression dive, stop depth alarm (decompression stop ceiling has been violated) and low battery. In audio mode, the diver would hear a beep or sequence of beeps; in visual, the diver would see the word "slow," up and down arrows and a ceiling bar (for decompression situations). In either case the information is clear and unmistakable.

The dive algorithm can be adjusted to accommodate the strenuousness of the dive. The conditions you can select are Normal or Hard, Hard obviously using a more conservative table. The display can be set for metric or imperial and altitude set for up to 7,872 plus feet in five altitude increments (A0 through A4) that change approximately every 2,000 feet (300 meters) above sea level. The computer is designed to operate to a maximum altitude of 11,480 feet (3,500 meters).

Surface intervals reveal even more information, such as surface time, no fly time (accompanied by an airplane graphic), dive number, dive time and maximum depth. For dive planning the Chameleon will scroll through no stop times for various depths.

To review a dive, go to the Memory mode. Here a diver can peruse the dive log (last 10 dives or 10 hours of diving, whichever comes first) and get information on maximum depth, dive number, dive time, surface time (if between 10 minutes and 12 hours) and which dive condition mode was selected. In Memory mode one can also review a dive profile. This will automatically display when you pause for five seconds on a dive in the dive log mode. The profile displays the dive in three minute segments. Average depth will be shown; surface times of less than 10 minutes will display as zero depth. Additionally, the dive profile will show if ascent rate, safety stop or decompression rate were violated. All in all, it's a nicely comprehensive review of a dive. Of course, for the more technically minded, the Chameleon is PC downloadable. And it has a user replaceable battery (without loss of dive profile memory - a big plus).

Negotiating through all these user adjustments and dive information is exceptionally easy and very well supported by the accompanying manual. There are plentiful graphics to ensure you're in the right place and doing the right thing. (Some of us need a picture demonstration in order to learn!)


For the nitrox side of this little powerhouse take all of the above and add these next few features.

First of all, if you become certified in nitrox and want to upgrade the Chameleon, all you have to do is visit your dive shop and five minutes later you're ready for the world of EANx. After you've upgraded a few things change.

Right off you'll see the Chameleon sporting a new look - a yellow housing back. Then you'll will notice the information on the display has changed. During the dive you still get the basics of dive time, depth, conditions setting and no decompression time, but two nitrox critical elements also appear: CNS (Central Nervous System) "clock" percentage (based on the amount of oxygen exposure you are allowed during a dive at a certain partial pressure) and your current oxygen partial pressure. Overexposure or exceeding either of these values could result in oxygen toxicity, which is why you must receive nitrox training before using it and why the information is so prominent on the display.

If you dip into a decompression situation the CNS percentage time is replaced by the ceiling depth reading and no stop time becomes total ascent time.

During the surface interval, the new nitrox particular information displayed includes the current CNS percentage and gained OTUs (oxygen toxicity units). This screen flashes back and forth with the total desaturation time (which is also the no fly time as shown by the airplane graphic).

Two new function modes you will access frequently when using nitrox are the Fraction of Oxygen (FO2) selection mode and Oxygen Partial Pressure Limit (PO2) selection mode. Because the Chameleon will default to 21 percent oxygen after 24 hours without a dive or one hour after FO2 has been set if it hasn't been dived (after a cold start), you should check and set the FO2 setting prior to the first dive of the day. This great feature forces you to physically set your FO2 after a cold start for a maximum amount of safety because nitrox has some very definite and unforgiving use limits (with nitrox certification this will become perfectly clear). Once you've set the FO2, it will stay for one hour or, if dived, until the 24 hour no fly period has elapsed; or until you change the FO2 setting to a different nitrox mixture. The Chameleon can be programmed for FO2 between 21 and 50 percent, in one percent increments.

The Oxygen Partial Pressure Limit mode is actually a safety margin setting. It can be set between 1.2 and 1.6. If the partial pressure is violated either the audio or visual alarms will react, warning you of a possibly dangerous situation. Like the FO2 setting, the Chameleon will reset the PO2 (to 1.2) after the unit turns off.

The Chameleon is made of rugged glassfiber ABS and depth rated to 216 feet. To easily distinguish between which mode the computer is set for, the air Chameleon has a gray colored case and the nitrox Chameleon has a yellow case. The Chameleon is powered by one lithium battery (SAFT LS3 or LS14250) that lasts for approximately 300 hours of diving. The computer is equipped with an LCD light for night diving or low light conditions. To activate the backlight the unit should be tapped with a hard object or fingertip. The light will remain on for seven seconds and then turn off automatically, for battery life conservation.

The wrist model Chameleon sells for a very attractive $299. It's an easy to use, full featured air or nitrox computer that has everything a new diver should look for in an air computer and everything required for the unique requirement and demands of nitrox diving.


Even if you never decide to try nitrox, the UBS Chameleon is still a powerful, full featured dive instrument. And if you do get nitrox training, it's nice to know within your air computer lurks a tiger of a nitrox computer waiting to be set free with the quick flip of a switch. The manual is exceptionally clear and concise, which is breath of fresh air when navigating through the Chameleon's many features or upgrading from air to nitrox.

For more information on the Chameleon, call Undersea Breathing Systems, Inc., at (888) 5NITROX or e-mail cha

Source Citation
Sawyer, Ty. "Air/nitrox: double your pleasure." Skin Diver July 1998: 8+. General OneFile. Web. 10 Jan. 2010. .

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