tec computer for occasional tec dive recommendations?

[xrcjdx]

greetings,
i am just completing my sdi advanced nitrox and deco procedures e-course and will take the dive components soon. my objective is to up-skill, and do not expect to be doing all that many deco dives in the future, but there will be some no doubt.
i am diving an ai oceanic vt4 now and have hundreds of dives on it (no troubles by the way). i know it has gas switching capability. i have as well an aeris that can be used alongside the oceanic in guage mode.
i have been searching the threads here to find a few opinions about computers that might meet my needs, but not finding any truly on point. my question is, considering i expect to do only a few deco/gas switching dives each year, with absolutely no intention of ever learning trimix or rebreather, does it make sense to invest in a tec computer (shearwater, for example), or am i better off relying on the computers i have?

 

[Lorenzoid]

There's a school of thought that says you don't NEED any computer for tec dives. GUE's courses don't make use of computers.

 

[northernone]

Often safer to keep using what you know and understand when adding complexity in a new situation.

If your dive computer does what you need, I'd keep it.

Otherwise, a shearwater (or the like) is nice with more flexibility even if you don't need all the features.

 

[BoltSnap]

You are still going to have to do manual planning for the dives for the deco/air part anyways, I don't see the need to spend money for a new computer since you have two that are very capable computers with one of them used as a digital BT based on what you said. Even if you change your mind later, there is no reason for you to spend the money now on a computer that you less likely to use its technical features in the future. Buy it when you actually need it if ever since at that time newer computers with more up to date features will exist.

 

[scubadada]

Hi xrcjdx,

I've been diving Oceanic computers, running DSAT, since 2002, about 1200 dives. I have been diving a VT3 primary and a Geo2/SPG backup for the last 6 years. Most of my dives are within recreational limits, but I do light deco on about 5% of my dives (avg deco 5 minutes, 2-14 minutes). I am not trained in, nor have I ever done, accelerated deco or gas switching.

As you know, the DSAT decompression algorithm was developed for recreational diving. I'm not sure, nor is there documentation, about how it specifically deals with deco. It has always seemed to me that it quickly piles on deco time at the shallowest stop, I have never had a stop at 20 feet. The proprietary PZ+ decompression algorithm may be more suitable for deco diving but I find it too conservative for my recreational diving. Recently, I purchased a Dive Rite Nitek Q as a backup computer to get experience with Buhlmann ZHL-16C with GF. I run it at GFs that match my VT3 relatively closely, generally requiring GF hi of 95-100. I only have about 50 dives on it but have already learned quite a bit, including how the algorithms treat deco. Of course choice of the GF lo will largely dictate the ZHL profile

Despite my limited forays in tech, my next primary computer will be AI, running ZHL with GF. Of course I'm waiting for one that fits my needs. The Nitek Q will remain my backup. I have been using MultiDeco for some time now to simulate profiles though it does match DSAT well at all. It matches the Nitek Q quite closely.

For my diving, which is relatively aggressive and includes limited deco diving, I've decided to switch from DSAT to ZHL. If I were intending on doing any more serious deco diving, I would make the same choice. I want the ability to specifically dictate the ascent profile to meet the dive and my personal requirements. I also want the ability to use available planning software to plan and simulate my dives. Obviously, I'm fond of DSAT, but, it's time for me to let it go and move on.

Good diving, Craig

 

[Scared Silly]

The only reason to switch is because you want to switch. We moved to Shearwater Petrel/Perdix simply because they are so much easier to read underwater and it was easier to match cut tables. That said at times I wish I would have kept my old AI computer just to keep track of gas usage.

 

[OMANDIVER]

Do the course first would be my view. For a few deco dives a year what you have will be fine as long as one has gauge mode, or get a uwatec/scubapro bottom timer. If you want to spend money, shearwater is good news, you can use GF or VPMB which gives you some flexibility in terms of using same algorithm as others you may be diving with. Dont believe your head when it says you have no intention of learning trimix.....

 

[wetb4igetinthewater]

at times I wish I would have kept my old AI computer just to keep track of gas usage.

Exactly. I kept my AI computer for that reason. I'll always use AI when dives permit. Obviously not during my upcoming GUE fundies class that starts on Thursday

 

[xrcjdx]

wow. thank you for the great advice and i sincerely appreciate that you took the time to give me a well thought out response. i get it. if/when the time comes to move forward, i'll know. thanks again.
ralph

 

[Diver0001]

greetings,
i am just completing my sdi advanced nitrox and deco procedures e-course and will take the dive components soon. my objective is to up-skill, and do not expect to be doing all that many deco dives in the future, but there will be some no doubt.
i am diving an ai oceanic vt4 now and have hundreds of dives on it (no troubles by the way). i know it has gas switching capability. i have as well an aeris that can be used alongside the oceanic in guage mode.
i have been searching the threads here to find a few opinions about computers that might meet my needs, but not finding any truly on point. my question is, considering i expect to do only a few deco/gas switching dives each year, with absolutely no intention of ever learning trimix or rebreather, does it make sense to invest in a tec computer (shearwater, for example), or am i better off relying on the computers i have?

I don't have any experience with the Oceanic computer you have but I looked it up on Google and on paper it has everything you need. You should set it to the Palagic Z+ algorithm for technical diving and keep in mind that it will be running pure Buhlmann (or so it looks) so the ceiling it gives you will look suspiciously shallow even if you pile on a lot of time.

What I would do if I were in your position is keep the computer you have but ease into it. Keep the deco obligations down to about 15min until you get a feeling for it, slow the ascent between 18m and 6m to 3m/min, make the last stop at 6 or 5 meters even if the computer is saying that the ceiling is shallower than that and extend your last stop a few minutes beyond what the computer thinks, especially at first, and then dial in from there.

Since this computer is probably going to give you only basic information then it's a good idea to build up as much knowledge as you can about what the algorithm is doing and why. If you haven't already then I would recommend carefully reading Mark Powell's book and familiarizing yourself with the concept of gradient factors so you can feel your way into a reasonably good ascent curve even if the computer isn't calculating the entire ascent curve for you.

R..