16 September 2005

Gear Review: Mares Nemo DiveWatch

"If you want a wrist computer that offers all the bells and whistles with the added bonus of sex appeal then the Nemo is for you".

My first encounter with the Nemo was at the Oaks pub in Sydney after DOUCAP 2004. A group of us were sitting around the table and Chris Holman (commonly known as 'Captain Zeagle') joined us. The only reason he joined us was to show off the new toy on his wrist… the Mares Nemo. There was much fondling and button pressing and by the time I'd finished playing with it I knew I had to have one. It was like Gollum with his 'precious' ring…oh yes, the Mares Nemo shall be mine!

Well it took me 6 months but I finally ended up purchasing a Nemo to use with my new Sports KISS rebreather. Most rebreather divers use a VR3 but I couldn't justify the expense plus I didn't require a technical diving computer for the shallow diving I generally conduct. I purchased the Nemo because I wanted a wrist mount computer that I could wear on trips away and it reduced the fact that I had to take a watch; the Mares Nemo is my new wristwatch!

I have had the Nemo for two months and have conducted 30 dives with it to varying depths. A lot of my dive buddies have been inquiring about its functionality so I figured I might as well put something together to share with everyone.

The Computer:
The Mares Nemo is designed and manufactured in Italy and utilises swiss-made components that are housed in a titanium or brushed stainless steel casing. The wrist strap is made of rubber and an additional strap is also available to make it easier to wear over drysuits. It fits very comfortably on the wrist and is about the same size as my standard Seiko diving watch but the Nemo looks a hell of a lot better!.

The Nemo utilises the Mares version of the Reduced Gradient Bubble Model (RGBM) algorithm including a deep stops protocol. Now I'm not even going to try and claim that I understand diving algorithms a so I have 'borrowed' the following from the Mares website which explains in detail how the Mares-Wienke RGBM model works:

  • "RGBM is a mathematical algorithm that considers in parallel both the passage of gas from its dissolved state to its free state, the coupling between free and dissolved states, and new theories about micro-bubbles that grow from seed nuclei. These seed nuclei are most likely produced by exercise, that is, frictional excitation (tribonucleation) due to diver tissues rubbing together. The micro-bubbles do not cause noticeable symptoms, but they are nonetheless present, and can only be detected using sophisticated laboratory instruments. They can be present in tissues and blood. These micro-bubbles in tissues and blood can create decompression sickness.

  • Using a sample of 20,000 monitored dives, statistical studies have found the presence of micro-bubbles in the bloodstream in 67% of cases in divers who used traditional decompression models. The studies on RGBM were developed by Dr. Bruce Wienke, a scientist at a laboratory in Los Alamos, in the United States. Dr. Wienke is the author of many scientific publications about phenomena connected to underwater diving.

  • He is a consultant with various universities and research centers, and is considered to be among the world's top authorities in the field of research on decompression theories. In 2002, Dr. Wienke collaborated with Mares in the most recent evolution of the RGBM algorithm, which takes into account the most recent studies performed in this sector. Thus, the RGBM Mares-Wienke algorithm was born. The Mares-Wienke algorithm is indispensable for anyone who takes multiple and repetitive dives. Further, the algorithm adopts data correlations for bubble correction factors, using statistical analysis. The Mares-Wienke algorithm is the first to introduce deep decompression stops, increasing the possibility for micro-bubbles to be eliminated."

    So the Mares-Wienke RGBM algorithm can be considered to be conservative and helps reduce the chance of a diver suffering from decompression sickness (the bends). It also incorporates deep stops and the Nemo notifies the diver if they need to conduct any deep stops during your ascent.

    During the dive the Nemo displays your current depth, the water temperature, your dive time and the remaining no-decompression time at the current depth. All of these features are displayed on the screen and at the push of a button you can also check your maximum depth for the dive. It also displays your ascent rate in metres/per min with digital readout and your ascent rate as a percentage of the maximum permitted speed. It also displays when you need to conduct a safety or decompression stop by showing what depth you need to be at the remaining time at that depth for the stop. All of the features are easy to read and on dark or night dives you can push the top button to illuminate the screen for several seconds.

    The Nemo also has a four level altitude function that caters for divers conducting dives at altitude. It also has an option for setting a more conservative program to increase the safety margins; this is useful for those divers that could be more susceptible to getting decompression sickness.

    After a dive Nemo will display the surface time, the desaturation time and the time to fly. It also records all the dives in the logbook feature. The Nemo is powered by a CR 2430 lithium 3V battery which will last for approximately 170 dives (dives of 45 mins duration) and the Nemo will display a warning if the battery becomes low. There is no loss of the Nemo memory during the battery change so all your dive data is still kept in history. This battery needs to be replaced by a qualified technician and should not be considered user-replaceable. The user can switch the Nemo 'off' if it is not going to be used for an extended period to conserve the battery; the history and time is still recorded.

    The maximum depth rating for the Nemo is 150 metres which is more than adequate for recreational diving and even most deep dives.

    On land the Nemo offers all the standard watch features such as date, dual-time zones, stopwatch, air temperature, backlight, alarms and it even tells the time too! And the best thing about it as a watch is that it looks pretty cool on the wrist.

    A clear plastic screen protector is available for the Mares Nemo for a recommended price of $29.95. I highly recommend the protector as it stops any damage to the watch surface and it is easy to remove after a dive.

    The Nemo offers full functionality for Nitrox and allows divers to set a Nitrox percentage from 21% to 50%, in increments of 1%. It also allows the diver to select their maximum Partial Pressure Oxygen (PPO2) from 1.2 to 1.6 bar. If using Nitrox the Nemo will also display your value for Central Nervous System O2 Limit (CNS loading) as a percentage and it will continue to track this over repetitive dives. This allows the diver to track their CNS loading and ensure it is not going too high.

    I was experimenting with the Nemo on a couple of dives using a rebreather and I set it to 50% Nitrox with a PPO2 of 1.4. This gave a maximum operating depth of approximately 23 metres. Well you should have heard the alarms go off when I passed 23 metres; the alarm is definitely loud enough to get your attention and alert you that you need to ascend to a shallower depth. The same loud alarm activates when you fail to complete a decompression stop; all testing was conducted with the 'safe' use of a rebreather. ;-) These audible alarms can be disabled if the diver chooses to however I recommend against turning the alarms off as they are very useful in alerting the diver.

    Free Dive Mode:
    One of the very cool features of the Nemo is that you can you select a 'Free-Dive' mode. This allows the Nemo to act as a bottom timer and records the bottom time of the diver in minutes and seconds as well as recording the maximum depth reached. This is a very useful feature for freedivers or even spearfishers wanting to keep track of their bottom times and depths. It also recorded the number of divers performed and the temperature for each dive.

    The Nemo has an excellent logbook function that stores the previous 50 dives in memory. It stores the last 50 dives (max 38 hours) in 20 second intervals which can then be download to the computer to see the dive profiles. The logbook has a history function that records the total number of dives, the deepest dive logged, the lowest water temperature measured underwater and the total hours of diving. The history function is excellent as I started using the Nemo at the same time as my rebreather so I can track how my hours and dives I have conducted with a rebreather. Much easier than using a logbook!

    The diving data from your Mares Nemo can be downloaded with the IRIS interface utilising the infra-red system. IRIS2 2.2.2 is the most recent version of the software and is available from the Mares website. The IRIS interface is connected to the computer via a serial port which is rather archaic in this day and age; rumour has it that the IRIS system will soon be made available via USB later this year. To the left are a couple of screen shots from IRIS showing dive profiles.

    I am really happy with the purchase of my Mares Nemo. I find that I wear it most the time now replacing my old wristwatch and it looks really good on the wrist. It is the most streamlined and compact of the wristwatch diving computers and it definitely looks the sexiest - that's important! I would suggest that the additional plastic face protector is purchased to protect it underwater from scratches on coral or rocks. Considering I now own four different dive computers the Mares Nemo is now the only dive computer for me…

    Contact Details:
    The Mares Nemo is now currently selling for the special price of $990. Ya might wanna find out if that price is for the Stainless or the Titanium one, and specify when ordering. Mares is distributed around Australia by Cape Byron Imports and can be contacted by calling (02) 6685 7185 or you can visit their website at http://capebyronimports.com.au . If you visit your local Mares dealer, you can enquire as to whether they have any Mares Nemo available for a test dive - its well worth it. Visit the Cape Byron Imports website for your nearest stockist.

  • This is the best looking wristwatch computer on the market - Period.
  • Uses Mares-Wienke RGBM algorithm, which includes deep stops if required.
  • Has 4 dive settings (Air, Nitrox, Bottom Timer & Free-Dive)
  • Allows setting of Nitrox to 50% and selection of max PPO2
  • Excellent audible alarms
  • Very easy to use and understand
  • The price - $990 is a bargain for the Nemo

  • A stainless steel strap option would be cool
  • It would be nice if it had a built in digital compass like the Suunto D-9
  • Needs a USB connector for IRIS interface
  • Battery is not user replaceable but can be replaced by qualified Mares technician (it does not need to be sent away which is good).

  • Functionality: 95%
  • Durability: 90%
  • Battery Life: 90%
  • Ease of use: 85%
  • Value For Money 90%
  • Final Score: 90%

    Source: www.diveoz.com.au


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