Computer or Not

[CIBDiving]

60': (Same source)

USN - 60
RDP - 55
DCIEM - 50
Buehlmann - 51
NAUI RGBM - 55
Vytec - 52
Aladdin Pro - 50
Cochran - 68

The numbers seem to get more consistent as the depths increase, to a point, but there is still significant variation. This is one of the things that made me realize, very early on, how much the various models are NOT carved in stone, absolutely accurate limits.

I don't know where you got your numbes but your Buehlman time is not correct.
ZH-L16C gives 61 minutes before a deco stop is required.
ZH-L16B gives 62 minutes before a deco stop is required.

 

[darkpup]

according to Lippman, Deeper into Diving

It's possible the source that Lynne referenced is wrong, but it also suggests there are differing opinions of what a Buehlman model will produce for a 60' dive.

Do you have any options turned on / off in your decompression software that may not be default?

Using Deco Planner set to a straight Buehlman model (not sure if it's 100% Buehlman) says 65 minutes at 60 on air. 66 minutes requires 1 minute of deco, and 70 minutes at 60' requires 3 minutes of deco.

IMO, it just shows the differences in models. Not even the same model run through different software packages will produce the same level of precision every time. It also suggests from looking at all of the different time limits Lynne referenced, that you have roughly 18 minutes between one model to the next at 60'. 10 minutes isn't going to kill you.

~ Jason

 

[rjack321]

Using Deco Planner set to a straight Buehlman model (not sure if it's 100% Buehlman) says 65 minutes at 60 on air. 66 minutes requires 1 minute of deco, and 70 minutes at 60' requires 3 minutes of deco.

Set 0/100? or 30/80?
I can't remember the "standard" right now.

10 minutes isn't going to kill you.

Yeah, but I've done some pseudo-Buehlman profiles on air quite awhile back (Oceanic Haldane algorithm to be exact) and boy did I feel whupped afterwards.

 

[darkpup]

Yeah, but I've done some pseudo-Buehlman profiles on air quite awhile back (Oceanic Haldane algorithm to be exact) and boy did I feel whupped afterwards.

The thing I find interesting is that if you wanted longer bottom time, get the Cochran Commander. If you want to be more conservative, go with a computer running an RGBM model. However, if you assume that a computer running an RGBM model will give you more bottom time, then you'd be wrong since the US Navy tables give you more time at depth.

Also, the 18 minute time difference between one model and the next from Lippman, Deeper into Diving, really shows how little real time information every 1 to 10 seconds matters in the long run. If I dive the air tables I dive regularly (60' for 50 minutes), I can mess up by 18 minutes, and still be relatively safe. That's a big Guber factor. If I was diving a computer, I'd be curious to see where it placed me in the curve.

~ Jason

 

[WarmWaterDiver]

I use a few computers - for scuba as well as other activities.

 

[rjack321]

Also, the 18 minute time difference between one model and the next from Lippman, Deeper into Diving, really shows how little real time information every 1 to 10 seconds matters in the long run. If I dive the air tables I dive regularly (60' for 50 minutes), I can mess up by 18 minutes, and still be relatively safe. That's a big Guber factor. If I was diving a computer, I'd be curious to see where it placed me in the curve.

Yeah the "real time" data thing is a bit of a fallacy. A "NDL remaining of 12:36" or whatever just looks so precise.

I think most computers would have you in the "yellow"

 

[darkpup]

Yeah the "real time" data thing is a bit of a fallacy. A "NDL remaining of 12:36" or whatever just looks so precise.

I think most computers would have you in the "yellow"

If yellow / red is indicated by a beeping noise, then judging by some dives lately, I believe my buddies computer had us in the red. Then again, it may not have been set for Nitrox, which seems like a common mistake from the chatter on the boat dives I've done over the years.

I'll have to see if I can push any of the computers into the red while working on the mapping project this weekend. I bet I can do it.

~ Jason

 

[rjack321]

Are you doing more than 1 min stops? I'm not doing looong 50-60' dives on doubles, so the limiting factor is the single tank RB. On a 50-60' dive I'm good for about an hour, maybe a little less since its been awhile.

I am curious about 90 mins at 60' and how people are feeling after that - esp. if they were doing 1 min stops.

No cheating by using the air setting.

 

[PaulChristenson]

The thing I find interesting is that if you wanted longer bottom time, get the Cochran Commander. If you want to be more conservative, go with a computer running an RGBM model. However, if you assume that a computer running an RGBM model will give you more bottom time, then you'd be wrong since the US Navy tables give you more time at depth.

Also, the 18 minute time difference between one model and the next from Lippman, Deeper into Diving, really shows how little real time information every 1 to 10 seconds matters in the long run. If I dive the air tables I dive regularly (60' for 50 minutes), I can mess up by 18 minutes, and still be relatively safe. That's a big Guber factor. If I was diving a computer, I'd be curious to see where it placed me in the curve.

~ Jason

If you are interested on the RGBM model...
http://www.rgbmdiving.com/index.htm

One of the more conservative dive computers dealing with deco is the VR3...I guess that's why they provide games and book options...
http://www.rebreatherworld.com/rebreather-accessories-articles/3908-vr3-vpm-vs-cochran-emc20h.html

 

[darkpup]

Are you doing more than 1 min stops? I'm not doing looong 50-60' dives on doubles, so the limiting factor is the single tank RB. On a 50-60' dive I'm good for about an hour, maybe a little less since its been awhile.

I am curious about 90 mins at 60' and how people are feeling after that - esp. if they were doing 1 min stops.

No cheating by using the air setting.

I'm not averaging 60' on those 90 + minute dives, and our ascents on those longer dives in the 110 to 90 minute ranges usually have long swims in the shallows leading back to shore.

~ Jason