Can anyone help me choose which used computer to buy??

[Dr. Deep]

You have quite the strong opinion for someone who was not there looking at the screens. Perhaps you should apply your omnipotence to the stock market and make yourself a quick buck.

*starts eating popcorn watching intently*

I have a friend at the LDS who has a Scubapro Mantis 2 watch he will sell me his for $200. I have bought a lot of gear from him and he's extremely generous and helpful. I owe him a case of beer, or two. He uses the Teric (w/ transmitter) and used the Mantis 1, and 2, as a backups. He believes the mantis is safer then the Geo 2.0, and is concerned that Oceanic still has the most conservative algorithm and might be a safety concern. My pops, the masterdiver, suggests the Geo 2, I can get it new from WikiBuy for $225. I am super healthy and fit and do have lots of air remaining even with moderate exertion on dives and dive with pros, not the O2 huffing beginners. I can't afford a Teric today, but I can afford either of these two computers! When I get my truck paid off in several months I'll just get a Teric and make everyone happy!

 

[scubadada]

*starts eating popcorn watching intently*

I have a friend at the LDS who has a Scubapro Mantis 2 watch he will sell me his for $200. I have bought a lot of gear from him and he's extremely generous and helpful. I owe him a case of beer, or two. He uses the Teric (w/ transmitter) and used the Mantis 1, and 2, as a backups. He believes the mantis is safer then the Geo 2.0, and is concerned that Oceanic still has the most conservative algorithm and might be a safety concern. My pops, the masterdiver, suggests the Geo 2, I can get it new from WikiBuy for $225. I am super healthy and fit and do have lots of air remaining even with moderate exertion on dives and dive with pros, not the O2 huffing beginners. I can't afford a Teric today, but I can afford either of these two computers! When I get my truck paid off in several months I'll just get a Teric and make everyone happy!

Hi @Dr. Deep

I think you mean the Geo 2, or any Oceanic, Sherwood, or Genesis computer, running DSAT, are among the most liberal dive computers. The Cochran is a bit more liberal, as is a Buhlmann with GF computer set appropriately. In fact, my Teric, running a GF high of 95, is a little more liberal than my Oceanic VT3 on many repetitive dives.

I have 1390 dives on DSAT since 2002, including about 5% light deco, and am alive and kicking to tell the tale. To say the Mantis, with shorter NDLs, is safer than the Geo 2, may be statistically true, but not of any real practical value. The difference here is a small fraction of an already very small number. If you are interested, you might want to take a look at the SAUL recreational planner, based on a probabilistic deco algorithm model SAUL Recreational Dive Planner | Modern Decompression

I wouldn't be surprised if the Mantis 2, at the most liberal MB level and without the other conservative factors, would work out just fine for you. The Geo 2 could be run on DSAT, but has the option of running PZ+, if you want to dive more conservatively.

Best of luck in your computer purchase and good diving,

Craig

 

[loosenit2]

*starts eating popcorn watching intently*

I have a friend at the LDS who has a Scubapro Mantis 2 watch he will sell me his for $200. I have bought a lot of gear from him and he's extremely generous and helpful. I owe him a case of beer, or two. He uses the Teric (w/ transmitter) and used the Mantis 1, and 2, as a backups. He believes the mantis is safer then the Geo 2.0, and is concerned that Oceanic still has the most conservative algorithm and might be a safety concern. My pops, the masterdiver, suggests the Geo 2, I can get it new from WikiBuy for $225. I am super healthy and fit and do have lots of air remaining even with moderate exertion on dives and dive with pros, not the O2 huffing beginners. I can't afford a Teric today, but I can afford either of these two computers! When I get my truck paid off in several months I'll just get a Teric and make everyone happy!

No popcorn needed, and sorry for diverting from your original request, I just don't like having my integrity questioned, triggers me pretty quick.

There is nothing wrong with any of the algorithms, some are more conservative, some are more liberal, others allow you the flexibility to program a level of conservatism you want. There are good reasons for choosing a very conservative algorithm (i.e. you got the bends once, are older, have condition that may lend itself to DCS etc etc etc). Only you can choose what is right for you but many folks choose a computer based on price or other factors without considering the algorithm, which is IMO one of the most important factors; it is after all what the computer is build around.

 

[GreggS]

Was not malfunctioning computer, was repetitive dive with 45 min SI, plan mode off same depths. I was surprised how drastic the difference was too. Had the COBRA 3 and a Cress Leonardo (both rgbm) as backup and both were reporting similar NDLs, only different by a couple of minutes, but both significantly different from my Teri’s in rec mode running buhlman16c

I have no idea what was going on with your computers, but my wife and I dive Suuntos and I have never seen a discrepancy in dive times like this before. I have done many dives with buddies diving different computer brands and we have never had an issue with mine being far ahead of theirs in terms of NDL times. In fact, being low of air has always ended dives before running out of NDL.

Just last month, my wife and I did a dive out of Wilmington, NC on the Hyde wreck sitting in 85 fsw. We did 2 dives on that wreck that day and the 2 of us were the first to splash on both dives. We did two 50 minute dives that day with a 50 minute SI and were the 2nd to last to come up each time. The only people to come up after us were an older couple with whom I presumed to be their granddaughter. I have no clue how much after we splashed that they went in but they came up about 5 minutes after we did.

I'm certainly not calling you a liar. But something is not right somewhere. That is just so far out of the norm for something not to be misread, malfunctioned, or some odd occurrence involved. And to be honest, if a Teric or any Shearwater is giving that much more NDL time than a Suunto, I do not want one. At my age (63) I'm not about to push limits that far. The more conservative algorithms are quite fine by me.

 

[dmaziuk]

No popcorn needed, and sorry for diverting from your original request, I just don't like having my integrity questioned, triggers me pretty quick.

Nobody (edit: except yourself) gives a toss about your integrity, get over yourself. The simple fact is, computers are consistent. If RGBM routinely calculated 30-minute shorter NDLs than ZHL16, it would've been doing that all the time and we'd all of us know it by now. Including Dr. Weinke and all the vendors losing sales on their overly conservative warez.

 

[dmaziuk]

I have no idea what was going on with your computers, but my wife and I dive Suuntos and I have never seen a discrepancy in dive times like this before. I have done many dives with buddies diving different computer brands and we have never had an issue with mine being far ahead of theirs in terms of NDL times. In fact, being low of air has always ended dives before running out of NDL.

I think 40-minute SIs could do this, but I strongly doubt they'd do the whole "25 minutes" on day one or even two. My experience with 40-minute SIs is limited to 2-3 tanks/day on square-ish profiles and on that schedule my leo was showing shorter than usual NDLs by mid-week. They were never shorter than the scheduled total runtimes, and by the time we got to SS they got back to infinite, but it was noticeable -- compared to our usual schedules with an hour from gear off to start gearing up and the long-ish tail end aka "extended SS" in the shallows.

 

[scubadada]

I am less skeptical of such a difference in NDLs. Perhaps the ZH-L16C was set on a high GF high like 95%. These computers are relatively more liberal, say compared to DSAT, on repetitive, rather than 1st dive. Perhaps the RGBM computer was set on a more conservative personal setting. Perhaps the RGBM computer was penalized on the 2nd dive by the shorter than 1 hour SI, and/or by a sawtooth profile, fast ascent, or some other prohibited behavior, on the previous dive. If @loosenit2 observed a 25 min difference in NDL, it's not the observation that is in question, it's valid explanation for the observation.

 

[GreggS]

I am less skeptical of such a difference in NDLs. Perhaps the ZH-L16C was set on a high GF high like 95%. These computers are relatively more liberal, say compared to DSAT, on repetitive, rather than 1st dive. Perhaps the RGBM computer was set on a more conservative personal setting. Perhaps the RGBM computer was penalized on the 2nd dive by the shorter than 1 hour SI, and/or by a sawtooth profile, fast ascent, or some other prohibited behavior, on the previous dive. If @loosenit2 observed a 25 min difference in NDL, it's not the observation that is in question, it's valid explanation for the observation.

Although IO've never dove a Shearwater DC before, I am aware that the algorithm is programmable. And I do know that the Suuntos can be set to more conservative with the personal settings. And I suppose that if the Shearwater is set to the most liberal and the Suunto to the most conservative setting, there could be a significant difference between the two on a second dive. after a short SI. It's just that I've not experienced such a difference in NDL times before diving with buddies using a different computer. And no one has ever complained to me or even said anything about cutting a dive short due to me running out of NDL time. But then, I'm by no means the most experienced diver in terms of number of dives. So could it happen? Sure, I suppose so. Like I said, I'm certainly not calling him a liar or questioning his integrity. It just is something I've not seen before.

 

[outofofficebrb]

I have dived with 2 Suuntos together for a long time. Almost all of my diving is repetitive diving, 4-5 dives a day for at least 7-14 days at a time. I recently moved to a different computer for both primary (Shearwater) and backup (Oceanic) while my partner is still diving the same 2 Suuntos (we had matching his/hers). I did notice on repetitive diving after almost a week of doing 4-5 dives a day, there was a substantial difference between the NDL I had on mine vs what he had on his.I remember this so distinctly because we were on a wreck towards the end of our trip and we had to come up from it. It sits in around 80 feet of water and towards the end of the dive we had to shallow up because of it and we were starting to get too shallow to really see it so we decided to end the dive shortly thereafter. It was definitely double digits, about 15-20 minutes., but I have not noticed such a large discrepancy only after a few dives. I was on either "low" or "medium" conservativeness on my Shearwater while my partner/dive buddy was on Suunto's A0P0 setting (the most liberal).

 

[GR8FUL]

Good choice. Check out the video(s) on how to use it. Did it come with a manual? If not you might be able to find a pdf. That said, you'll still probably have to watch the videos.

Good choice?? Hmm...maybe, but at the moment I'm not convinced. In OP I wrote that one of the requirements was that I wanted something "easy to use"--I don't think the GEO 2 fits that description. Or maybe I'm just mentally-challenged (highly likely!). Regardless, imo the manual sucks. I've already bought the online tutorial that outofofficebrb suggested, really hoping that helps...