Liqtor:
thanks uys acctually tried both of those already notta; guess itll be going back; probably buy a gemini instead.
Hi,
I traded in an Aeris 750GT for my Cochran Gemini. I found that the Aeris would occasionally loose the communication link with the transmitter, the signal was always able to be restored by putting the computer closer to the transmitter.
I had about 75 dives on the Aeris and was generally satisfied with the computer, but extremely dissasfied with the software on my PC.
The Cochran software while a little klunky gives me MUCH more control of the set-up and configuration of my computer. It also allows me to review the profile of my dives in much greater detail.
The Cochran Gemini gives me a lot of information while I am diving, of course I am making the decisions. The Aeris 750GT is fairly similar in layout to the Data Trans +, and I believe they use exactly the same software for calculations. The only difference that I am aware of is the slight difference in the display.
The Aeris 750GT tracks your breathing rate but it bases the calculation on the first few minutes of each dive. The major drawback to this method is you can not track your breathing rates along a time line of many dives. The Cochran can tell you how much air (or other breathing gas) you are using in liters per minute. This allows you to relate your air consumption from dive to dive and compare this rate with out of the water consumption if you wish.
The Cochran Gemini is rather more expensive than the Data Trans + but it is a more flexible computer for the future as your experience and training might have you doing more aggressive diving. No computer should replace proper planning for a dive, but it can allow you to deviate from your plan if the situation warrants it. Multi level dive planning is difficult to change in the middle of a dive. If you want to deviate from you plan any good computer can offer you added felxibility.
The information provided to you by the two computers is generally the same, and for that matter it is generally the same for most air integrated computers. The mathematical models and formulas will vary between different computers but they usually boil it down to generally the same information, namely the amount of minutes you can remain at a given depth, and information about oxygen toxicity factors if you are using Enriched Air Nitrox as your breathing gas. Most if not all computers will give you an indicator of your ascent rate, but so do the bubbles you exhale.
For my money the Cochran is the better computer. A nice (and redundant) configuration is A Gemini Tank Unit, A Monitor Wrist Unit (on your wrist), An Intelegent Wrist Unit (on a retractor, in a pocket, or on your SPG), and of course A Submersible Pressure Guage. This setup assumes two High Pressure ports on your first stage. This configuration gives you two timing devices, two depth guages, two tank pressure guages, and two computers making calculations if you should have a computer failure, and most importantly one human brain to make the choices.
The Cochran is more liberal at shallow depths, but about the same as you get below 90 feet. The Cochran allows you to add a level of conservatism prior to the dive while the Data Trans + does not. On the Cochran if you set the conservatism at "10" the computer will base its calculations on a depth 10% deeper than your actual depth, it will still display your depth correctly but the calculations to determine bottom time remaining will use the deeper number.
Happy and safe diving,
Mark Vlahos
