PDC with reading NDL/DECO and BT at the same time

[Remy B.]

I have a DC that give you all the dive info and alarms in dive mode, but no bottom time, I can select Bottom time but then it will not show the rest of the info and no alarms as well, I see other DC like Suunto is the same, Don't know if in all its models, the same for other DC you either select dive mode or bottom time mode, I have an entri level DC, the Mares Punk Pro, I assume ( and maybe wrong ) that there is a DC that give you both readings at the same time.

Sorry if this is a dump question and it is pointless to have both readings at the same time.

I carry a regular analog watch, but it is not a stop-watch, as well if I forget to take note of the time, then it is not really accurate bottom time records it become more a guess work

Thanks.

 

[tr3a]

I have a DC that give you all the dive info and alarms in dive mode, but no bottom time, I can select Bottom time but then it will not show the rest of the info and no alarms as well, I see other DC like Suunto is the same, Don't know if in all its models, the same for other DC you either select dive mode or bottom time mode, I have an entri level DC, the Mares Punk Pro, I assume ( and maybe wrong ) that there is a DC that give you both readings at the same time.

Sorry if this is a dump question and it is pointless to have both readings at the same time.

I carry a regular analog watch, but it is not a stop-watch, as well if I forget to take note of the time, then it is not really accurate bottom time records it become more a guess work

Thanks.

suuntos show your bottom time, I would assume all do

 

[Steve_C]

What exactly do you mean by BT. If you mean elapsed dive time, then the DC have it. If you mean actual time on the bottom, I am not sure how the computer would know how to compute that. Example 1, I descend to 30 ft and stay there and come up. Example 2, I descend to 30 ft but my dive buddy has an issue so we hang out there for a few minutes and then go down to 90 ft. How would the computer know when I was at bottom? You can always play back the record from the dive later and see what it is for the log book if you want. I just log total dive time.

 

[knotical]

As I read it, I think Remy is just asking to see bottom time concurrently with the other info.

fwiw, my Suunto Cobra3 shows what it calls elapsed dive time (sounds like bottom to me) in the lower right in dive modes.

edit:
Remy, I just downloaded the manual for the Puck Pro from the Mares website and it shows something called "dive time" in the lower left in dive mode. So perhaps I misunderstood your question.
If you're talking about switching to Bottom Timer mode, there should be no need to do that for the vast majority of scuba dives.

 

[Remy B.]

Yes my DC show dive time, but not bottom time, it can do so if I select the Bottom Time (BT) mode but the rest will be disabled, only will show depth and bottom time, no alarms no de rest of the information for your safety, like NDL, and DECO time, Temp, and others

 

[eelnoraa]

I have used a few dive computers, all can do both dive time remaining based on NDL and dive time elapse. They may not be displayed on the same screen, but info are certain there. What computer do you have? maybe it is time to read the manual

 

[gopbroek]

Mares has the manual on its website @ http://www.mares.com/common/__/11664.15cd99c7.dl . The manual does not detail out the dive mode very well but graphics of the various dive modes all show ‘Dive time’ as the lower left numerical value, this is what most refer to as ‘bottom time’. The bottom timer MODE is a different thing and other computers call it gauge mode, in that mode it does no NDL calculations. Here is a good discussion on the difference between a basic dive computer mode and a basic bottom timer mode of operation; http://www.scubaboard.com/forums/archive/index.php/t-290953.html

 

[knotical]

Remy, please explain your understanding of the difference between dive time and bottom time.

thanks,

k

 

[Remy B.]

Mares has the manual on its website @ http://www.mares.com/common/__/11664.15cd99c7.dl . The manual does not detail out the dive mode very well but graphics of the various dive modes all show ‘Dive time’ as the lower left numerical value, this is what most refer to as ‘bottom time’. The bottom timer MODE is a different thing and other computers call it gauge mode, in that mode it does no NDL calculations. Here is a good discussion on the difference between a basic dive computer mode and a basic bottom timer mode of operation; http://www.scubaboard.com/forums/archive/index.php/t-290953.html

That is what I'm refering to, thanks I will chech that post

---------- Post added September 28th, 2014 at 04:12 PM ----------

Remy, please explain your understanding of the difference between dive time and bottom time.

thanks,

k

Dive time is the total time in the water

Bottom time is the moment you start descending and reach your planned (or maybe not planned )depth plus whatever time you spent at that depth, the moment you start ascending your bottom time stops.

For example, I start descending at 13:00 reach the bottom at 13:10, stay at that bottom until 13:17 and then start ascending, my bottom time will be 17min, at the moment I Start ascending the de-gassing start

In the PADI log book on the left corner there is 3 things to fill in, one is bottom, total dive time, and total dive time up to date.

correct me if I'm wrong that is why I'm asking.

 

[knotical]

Yes, that definition of bottom time is useful, and is part of the protocol for using the PADI RDP.

However, since dive computers continuously monitor your depth, there is no need for that information.

If you are using your dive computer and also the RDP, which is an interesting exercise, and which I often do for the grins, simply either use the computer's dive time as bottom time, or subtract your best estimate of your ascent time.
What you'll likely find is that after a dive that was perfectly safe your computer will show no alarms, but you might see from the RDP that you went well beyond your limits. Since your dive was not a square profile, the RDP indicates an unwarranted concern.

And a note about off-gassing: Once you start ascending, it is true that some "compartments" might start off-gassing, but since you are still under pressure, other "compartments" will continue to on-gas. Think fast tissues and slow tissues.