So... I'm a commercial diver professionally and a cave diver recreationally. I've never dove Tri-mix because quite frankly commercial companies don't need no stinkin nitrogen. I am a surface supplied Heliox diver. I want to Dive Eagle's Nest and Diepolder sometime in the next couple of years. Anyone suggest a good Tri-mix computer? On the cheap.
Yes, I understand there needs to be a progression. Quite honestly, I came from the era where anything above 218' was doable on air. That's why I said "in the next couple of years".
Also, when reading the requirements for Diepolders it says "must have mixed gas certification by a qualifying agency". Does the ACDE count as a qualifying agency?
Thanks for the help.
Rather than invest in an unnecessary trimix computer, you could put that money into taking a course that would certify you as a trimix diver through an agency that is absolutely a qualifying agency for admission. It doesn't get much cheaper than a depth gauge and bottom timer for decompression instrumentation and being able to easily calculate your own decompression schedule underwater using your brain rather than an electronic one is free.
Planning a dive using software and sticking to that plan will help reduce the mental stress of unknown deco obligations provided by a computer. The ability to construct a deco schedule using ratio decompression, Fibonacci sequencing, or other methods of calculating deco quickly and easily on your own provides an additional reduction of stress, because if it becomes necessary to deviate from the plan, you can recalculate your decompression needs. Diving without a computer will allow you to make adjustments to your profile as you see fit based upon factors that the computer cannot consider. Doing so gives you the power and the freedom to decide your best strategy.
When diving in a team, divers with different computers can switch to gauge mode to stick together rather than have computers separate them. Since you may dive with buddies who don't use the same computer or algorithm that your computer uses, your dive computer may operate just as frequently as an expensive depth gauge and timing device as it does a computer. Opting for a simple gauge and timer saves on the high cost of a computer.
Some trimix divers seem to prefer computers because they are afraid of "chasing the run" when it comes to software generated tables. However, this really isn't an issue because slight delays in the ascent often act as a safety margin. You need to do all of your deco. You can be a little late, but being too early is a problem. For example, losing a minute here or there during an ascent will simply carry you from a nominal, to a +1, or a +2 or greater conservation factor on V-Planner.
If you really do want a computer though, your best bet is to buy used. Used computers are sometimes sold because the owners opt to switch to digital depth gauges and timers. Also, if you are contemplating a computer for trimix, you may want to explore the computer's usefulness with any rebreathers you may be interested in should you decide to go that route. That way, if you do invest in a computer, you will get more bang for your buck.
As far as admission into Diepolder goes, I don't think that a commercial or military rating would qualify since the methods in which gas is used in those fields differs from the methods used in sport cave and technical diving.
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