What computer would you recommend for Tek Diving?

[chachee99]

I recently finished my Tek 1 course and looking for a new dive computer. I thought my old computer would work, but it locks for 2 days if deco is reached. So basically i was forced to switch my computer for a bottom timer. Now I am looking for a new tek computer. I plan to continue with tek diving and complete my trimix certifcation in the future. I want to purchase a computer i won't have to replace for many years.
Any suggestions?

[Captain CaveMan]

Most of us tech divers do not use computers to calculate deco but use bottom timers. We just plain our dive with tables and dive our plain. I would never use a computer on the fly. I'm 100% DIR so my answer will not be the one your looking for.

[Jim Lapenta]

OMS or UWATEC bottom timer and tables. Until you actually get into full trimix you won't really know what your requirements are. You'll still have to cut tables as backup anyway. So this will be great practice. If you insist on a computer though it will need multigas, switchable on the fly, whatever deco software your tables are based on, and easily used. So VR3, Liquivision, Nitek X, or perhaps a Cochran or Shearwater. In any case you will spend at least $1000 USD and likely alot more.

[BabyDuck]

i got a used vr3, but if i suddenly became really rich, i'd get a liquivision.

[reefraff]

I recently finished my Tek 1 course and looking for a new dive computer. I thought my old computer would work, but it locks for 2 days if deco is reached. So basically i was forced to switch my computer for a bottom timer. Now I am looking for a new tek computer. I plan to continue with tek diving and complete my trimix certifcation in the future. I want to purchase a computer i won't have to replace for many years.
Any suggestions?

http://www.microsoft.com/windowsmobile/components/devices09/imageengine/imageengine.aspx?img=/windowsmobile/en-us/assets/images/devices09/47-1-FrontLarge.png&scale=100
You're looking for an OC trimix computer and they (a) are few in number, (b) cost a ton of money, (c) may cause as many problems as they solve, and, (d) aren't really the answer. CCR is a different world but by the time you can be ready for that everything will have changed.

Better to invest in a PDA that you can load one of the programs (GAP, VPlanner, DecoWeenie) that will allow you to plan your dives and cut custom decompression tables. Take your tables and a bottom timer in the water with you and leave the computer topside.

That said, here's what I do: I plan my dives using GAP and/or VPlanner on a PC or my PDA and print out tables specific for each dive that I carry with me in the water. I use a Vytec as a computer for recreational multi-day/dive days and put it in gauge-only mode as a back-up bottom timer for the decompression stuff because I like it's log functions. On decompression dives, I bring along a ScubaPro Tec2 as my primary bottom timer because it's easy to operate the countdown timer with heavy drygloves on - it's a better (though more expensive) bottom timer than my bottom timers.

[ianr33]

(c) may cause as many problems as they solve,

Could you expand on that? I am trying to justify a Shearwater. What problems could it cause?

[Jorgy]

Can I ask you to explain your comment........

"but it locks for 2 days if deco is reached"

Thanks......

I have gone deco 4 times on my Suunto, once by accident with me even realizing, I only saw the deco when I downloaded the profile, the other times I knew I was in deco. I just made sure the computer cleared the deco obligation before I surfaced.......no issues.....

M

[dab]

Liquivision X-1

[wedivebc]

Most of us tech divers do not use computers to calculate deco but use bottom timers. We just plain our dive with tables and dive our plain. I would never use a computer on the fly. I'm 100% DIR so my answer will not be the one your looking for.

Do you actually believe that most tech divers are DIR? Only on the internet. I think most tech divers actualy do use dive computers once they start seeing the benefits.

[Captain CaveMan]

Do you actually believe that most tech divers are DIR? Only on the internet. I think most tech divers actualy do use dive computers once they start seeing the benefits.


Some of tech divers do like (CCR and Cave divers) like to use computers but in ocean and lake diving our profiles are so square there's no need for a $$ computer. If you base your dives on the fly with a computer and the computer fails THEN WHAT? SOL is what.
Written tables and backup tables are the way to go. This the best to go. Look at Wkpp exe.

Plan your dive, dive your plan. If the dive hit the fan get you backup tables out and come home alive and safe.

[kenseal]

I've used a Dive Rite He (Helium capable) computer for my tech diving since June of 2005 and it's worked great for me but I never did pursue taking the trimix class. I'm going to be putting it up for sale here soon to get a hoseless or air integrated computer. If you're interested I can send you pictures and let you have it for $600 instead of the $1,000 you would have to spend for any other kind of multigas computer. It can switch up to seven gases and also be used in gauge mode. I will let you know that the one thing I don't like about it (and others) is the font size is kind of small because they have to get a lot of information on the screen. I'm in my mid-fifties now and my eyesight is not as good as it used to be. That's that main reason I want to get a larger screened computer.
Ken Seal

[DwayneJ]

Can I ask you to explain your comment........
I just made sure the computer cleared the deco obligation before I surfaced.......no issues..... M

Suunto's are only recreational computers. The deco obligations they throw you are likely to be more conservative than if using tables/software/full deco capable computer. Their "deco" capability will get you out of the water. Although your Suunto does not "lock up", many rec computers do. For all the talk that Suunto publishes about deco capability, they need manual backup via tables which requires some alignment between software/written tables and the computer itself. Additionally, as a trained deco tech diver, using only one gas mixture (air or nitrox) for your deco diving is a major limitation.

That being said, I use a VR3-HD and my buddy uses a Suunto. My VR3 settings are not aggressive but my buddy reaches NDL limits sooner than I do. When I'm down to 7-5 mins of NDL time, my buddy will be at NDL limits. Of course he is looking at bars on a bar scale and I'm counting down minutes. I love my VR3.

D

[Jorgy]

Still a little confused, the OP stated "my old computer would work, but it locks for 2 days if deco is reached"......I was just not aware of any modern rec computers that would "lock" unless the deco obligation was not met.......:)

I agree, the Suunto (or other rec computers) deco is probably much longer than required (an aside - that would be an interesting comparison).....the OP must have been using tables or another computer to get out of the water before his computer cleared, therefore locking it up......I guess.....

Of course, I would just leave the computer hanging at 15 feet until it cleared, rather than lock it up, if I had the gas it would be on my arm, if not it would be tied to the line or on the end of my spool.....:)

My Gekko's and Vyper's count down NDL in minutes, I don't even see the cumulative bottom time bar, I leave it in Nitrox mode all the time, just set to 21% O2 when diving air and it shows OLF instead of CBT.

M

[wedivebc]

Still a little confused, the OP stated "my old computer would work, but it locks for 2 days if deco is reached"......I was just not aware of any modern rec computers that would "lock" unless the deco obligation was not met.......:)



Yes but when using higher O2 mixes to accelerate off-gassing you need a computer that is aware you have changed breathing gas and can deal with the higher O2 mix. Most rec dive computers will just lock up if the diver follows tables using accelerated deco profiles.

[Jorgy]

Good point.......in your scenario, my Vyper would be hanging at 15 feet.......:)

While I would be safely out of the water..........
M

[ssturges]

That being said, I use a VR3-HD and my buddy uses a Suunto. My VR3 settings are not aggressive but my buddy reaches NDL limits sooner than I do. When I'm down to 7-5 mins of NDL time, my buddy will be at NDL limits. Of course he is looking at bars on a bar scale and I'm counting down minutes. I love my VR3.

D

Your VR3 might be more aggressive than you think, see the following link

Message from the Head Divemaster (http://www.bikiniatoll.com/divemaster%20advice.html)

Quote from the link:
VR3, both generations, by Delta-P
"We have noticed a trend with the VR3 Dive Computer that I feel needs to be brought to our customers attention. Statistically over the past year we had an alarming number of divers show potential signs of DCS when diving with the VR3. In none of the incidents reported to us by our customers was there an error on the part of the diver. Due to the nature of the diving we carry out on Bikini please ensure you are fully familiar with the variable settings on this computer. I strongly recommend you completely understand why and how to program the device to ensure a strong safety margin when diving at Bikini prior to your departure. (This may just be an unpleasant coincidence, however I feel it is important to relay this trend to potential customers.)" - Jim Akroyd, Head Divemaster, Bikini Atoll Divers

[ianr33]

That quote is from a company that was in the business of renting out DiveRite computers.

Everything I have ever heard about VR3's points to them being very conservative. On my deco course the instructor tied his off to a line at 10 ft to get it to clear.

Last weekend I was supporting a couple of buddies. One on tables,other on a VR3. The VR3 gave an extra 20 minutes or so deco.

[chachee99]

Can I ask you to explain your comment........

"but it locks for 2 days if deco is reached"

Thanks......

I have gone deco 4 times on my Suunto, once by accident with me even realizing, I only saw the deco when I downloaded the profile, the other times I knew I was in deco. I just made sure the computer cleared the deco obligation before I surfaced.......no issues.....

M


I am using a Cressi-Sub EDY dive computer. it is a great computer for recreational diving, but it is not very handy for TEK. Basically here is what happened. I did my first decodive at 45 meters. As expect, the watch started beeping like crazy when I came close to the NDL and really started beeping and flashing like crazy when I went into DECO. Again, I expect this. For the first dive it everything worked like a charm. No problem. Later that day we did another deco dive. My computer was still flashing DECO and I could not switch it to gage mode. I was hoping it would still be able to display the depth and time of the second dive. However, as we decended into the water I noticed that the Cressi would not register anything. So rather than abort the dive, I just used my instructors Uwatec bottom timer instead and followed the dive plan on my arm slate. He used the VR3.

When I surfaced i noticed i noticed that the Cressi would continue to flash deco. It would not allow me to go into any other settings. It would only display the current time of the day if i pressed the mode button. The computer was locked like this for two days.

Once the computer was unlocked. I changed it to gage mode and used it as a bottom timer. I kept using the dive shops Uwatec bottom timer along with the gage mode. I kept them both on the same arm and noticed that the depth on the Cressi read around a meter less than that on the Uwatec. The dive time on the Cressi seemed to be off about 40 seconds too. My instructor said that probably my computer was callbrated for fresh water instead of sea water. However, I checked the manual and it stated that the Cressi- EDY is callibrated for salt water. We were diving at the same depth His VR3 matched the depth on the Uwatec.

So basically the Cressi EDY isn't a very useful computer for tek diving. Not even in gage mode because it gives a different reading than a bottom timer.

[DwayneJ]

Your VR3 might be more aggressive than you think, see the following link


Thanks but I think its about understanding the full capabilities of the computer and I have a high degree of confidence in the manual/software tables backed up/confirmed by the VR3's tables and actions.

For multiple gases, you have the option to enter a different PPO2 value and associated maximum operating depth. The computer has a general safe setting which increases its conservatism.

I'm happy with it.

[Jorgy]

Thanks for the details........

It is strange, on your first dive you cleared the deco obligation on the computer yet it still locked out on the second dive........

I wonder if Cressi wants you out of the water for an extended period of time after any deco dive even if you fully clear the deco obligation on the dive........perhaps like a "no-fly" count down..........

Very interesting.........

I will go back and look at my deco dives and see if there is anything I can see from my profiles........

I do agree with everyone, that a rec computer is not the answer for technical diving, just trying to better understand dive computers in general..........

M

[ianr33]

A computer that does not revert to gauge mode after being bent is pretty dumb. I have a simple Aeris 1 gas nitrox computer that I use on Trimix dives. Sure it gets bent after 1 dive but then it thinks its a bottom timer. (And before I get flamed I use a Uwatec bottom timer as well)

[Nemrod]

Since "tech" diving implies mixed gases and multiple breathing mixes in use on a single dive I cannot see how any computer could handle such profiles which is why most "tech" divers who actually do tech diving use a bottom timer and depth gauge or similar and the appropriate tables.

N

[TheMadDane]

Very informative, thanks guys.

[Shearwater]

Actually, tech computers handle these situations very well. The more complicated the situation is, the bigger advantage they have.

Although I can't prove it, I really doubt that most tech divers don't use computers. Certainly in my experience, people on boats I have been on in the last 10 years overwhelmingly use computers.

I guess we have different experiences.

Bruce


Since "tech" diving implies mixed gases and multiple breathing mixes in use on a single dive I cannot see how any computer could handle such profiles which is why most "tech" divers who actually do tech diving use a bottom timer and depth gauge or similar and the appropriate tables.

N

[Nemrod]

Actually, tech computers handle these situations very well. The more complicated the situation is, the bigger advantage they have.

Although I can't prove it, I really doubt that most tech divers don't use computers. Certainly in my experience, people on boats I have been on in the last 10 years overwhelmingly use computers.

I guess we have different experiences.

Bruce


Perhaps in another thread you could provide the information on how that is done. Seriously, how do they work, how does the computer know when to shift from a trimix to a deco mix etc? Being as I am not DIR I can use a computer--lol. Of course, I might have to sell my Jeep to buy one. Do you pre-program your profile?

N

[Shearwater]

I'll write something and post it. Stay tuned.

Bruce

[wedivebc]

Perhaps in another thread you could provide the information on how that is done. Seriously, how do they work, how does the computer know when to shift from a trimix to a deco mix etc? Being as I am not DIR I can use a computer--lol. Of course, I might have to sell my Jeep to buy one. Do you pre-program your profile?

N

Although some computers can do gas switches based on depth, I have been less that satisfied with the results. I prefer to tell the computer when I switch gases not let the computer tell me.

[DwayneJ]

Since "tech" diving implies mixed gases and multiple breathing mixes in use on a single dive I cannot see how any computer could handle such profiles which is why most "tech" divers who actually do tech diving use a bottom timer and depth gauge or similar and the appropriate tables.

N

Attached is the VR3 manual...

http://www.vr3.co.uk/downloads/manuals/HD%20VR%20Manual.pdf

... and since Shearwater have been so helpfull, a link to their manuals...

http://www.shearwaterresearch.com/pages/library/

Very simply - Enter your gases and PPO2 set points to allow the computer to calculate MOD's for the various gases. Computer will calculate stops optimizing the gases you have available to minimize deco time.
You can switch gases when the computer recommends doing so.
You can switch gases when you want to.
You can stay on the same gas and ignore the computers recommendation.

These computers support nitrox, trimix, closed circuit, and bailout options as well. Ideally you would plan your deco dive with software/tables as well.

[Shearwater]

As you requested:
http://www.scubaboard.com/forums/4196220-post1.html


Perhaps in another thread you could provide the information on how that is done. Seriously, how do they work, how does the computer know when to shift from a trimix to a deco mix etc? Being as I am not DIR I can use a computer--lol. Of course, I might have to sell my Jeep to buy one. Do you pre-program your profile?

N

[skippy31]

A computer that does not revert to gauge mode after being bent is pretty dumb. I have a simple Aeris 1 gas nitrox computer that I use on Trimix dives. Sure it gets bent after 1 dive but then it thinks its a bottom timer. (And before I get flamed I use a Uwatec bottom timer as well)

I found this to be one of many nice things of the Liquivision X1 utilizing V-Planner live. You can force the computer to switch to 50% Nitrox at 200 feet, and it will do it. You'll get a flashing warning, but it will keep calculating. You can then switch back and continue your dive. You can exceed the recommended stop a little and it will keep calculating. You can pull your stops deeper than it tells you and it will keep calculating.

I found it nice to use a computer that would not go into error mode immediately if you make a mistake or modify your plan. A computer simply shutting down and going into some type of error mode is not all that helpful. Switching to guage mode is also not ideal although a better option than error mode.

Of course the output the computer is only as good as the user input. In real life you'd want to follow the computer recommended stops fairly closely. Although there are real life scenarios where you may want to modify your plan a little and it's nice to have a computer that can handle this.

Mat.

[Colliam7]

I plan to continue with tek diving and complete my trimix certifcation in the future. I want to purchase a computer i won't have to replace for many years. Any suggestions?Back to the original question - which computer. I have been diving a Nitek He for several years. Works well for multi-gas diving, including deco with several gases. Also handles helium mixtures. The problems are not with the computer, the deco algorithm, etc. Rather I find the display hard to read, particularly at depth, in dark / low vis conditions. Now I have added a Liquivision X1. Highly (and I would underline that, put it in bold face italics, and add exclamation points) recommend the X1, based on ease of use, and the best / brightest display i have encountered (and time that displays seconds). If you are already spending the money to move into trimix, spending the $1700 or so on a X1 is really not that big a deal.
Personally, I find the debates about the relative 'conservatism' of different computers to be interesting. Generally, one sentiment seems to be that 'some computers are too conservative, so I will look for a less conservative one.' Is this somewhat akin to repeatedly asking a question until you get the answer you want to begin with. I cannot comment on the relative 'conservatism' of different units, rather I continue to cut tables, dive my plan, and use my computer as an important secondary source of information. I figure that whatever software I use for tables (DPLAN in my case) will provide a reasonably appropriate dive plan.

[rongoodman]

The Liquivision has a beautiful display, a nice interface(taps, no buttons) and can be wired into your CCR if you go that way in the future. It also lets you use the software/decompression model that you wish, currently either VPM(V-Planner Live) or Buhlmann GF(GAP).

[H20lover]

...Plan your dive, dive your plan. If the dive hit the fan get you backup tables out and come home alive and safe.

I have to agree with the Capt. As Tech goes, you must plan your dive and dive your plan. Sorry, there is no room for "fudging". :shakehead: But if you must dive computers I would recommend the Liquidvision X1. Still, I would make sure my tablet is with me. (I want to be able to go home.)

[DwayneJ]

The Liquivision has a beautiful display, a nice interface(taps, no buttons) and can be wired into your CCR if you go that way in the future. It also lets you use the software/decompression model that you wish, currently either VPM(V-Planner Live) or Buhlmann GF(GAP).

Buhlmann/GAP is not available for the X1 - Still in "Beta" now for the last 4-5+ months.

[Liquivision]

Buhlmann/GAP is not available for the X1 - Still in "Beta" now for the last 4-5+ months.

GAP has been available for the X1 for over a year. Sure, the manufacturer still calls it a beta release, but that is their choice, and simply a warning that there could still be bugs.

There is also a new, 3rd software package being released for the X1 at Beneath the Sea in late March.


Eric Fattah
Liquivision Products

[Scuba-Stu]

Most of us tech divers do not use computers to calculate deco but use bottom timers. We just plain our dive with tables and dive our plain. I would never use a computer on the fly. I'm 100% DIR so my answer will not be the one your looking for.


What else comes out of your mouth when I pull the string?

+1 for Liquivision

[cwkline]

Most of us tech divers do not use computers to calculate deco but use bottom timers. We just plain our dive with tables and dive our plain. I would never use a computer on the fly. I'm 100% DIR so my answer will not be the one your looking for.

All the dives I have been on every one of us had a computer. We also cut tables and "plan the dive, then dive the plan". But stuff happens. You could go deeper, stay longer, or do the opposite. The tables are the bible, but no one leaves the water till the computer clears (or gas runs out).
To the OP, I use the VR3 in monochrome. And contrary to what has been posted, it is a fairly conservative computer. I set V-planner on conservative level 4 and pretty much matches on run time. You also tell it when you switch gasses, it is not automatic. If you forget to acknowledge a switch, it calculates remaining deco on backgas. (You only do that once). YMMV
Charlie

[Captain CaveMan]

To me Tables are very easy to read and understand. Having changing the programed gases on the dive adding more load tasking that's not need. ( too much for me)

As too Cwkline "You could go deeper, stay longer, or do the opposite."

Tech diving take Discipline not to go deeper than your MOD ( ether MOD set by team or MOD by ppO2 , Dive time exe. In TDI ADV nitrox and Deco you learn not to break that rule.