Dive computer as bottom timer

[NJMike]

Hmm...this is all very interesting but I'm starting to think I had the wrong idea of what a bottom timer is. I thought it was nothing more than a stopwatch....so that you could time your stay at depth. I also thought that a countdown stopwatch would be the best way to go...diving to 115' and your max bottom time is 40 min? Set the countdown to 40 min, when you start your descent, hit the 'start' button.

If it could display the total dive time in addition to a countdown timer, that would be ideal....

I looked at the links above and did not find anything that was a basic timer or had a countdown timer. (The suunto D3 had one, but not in gauge mode, according to what's on the website. However, sometimes websites don't give you all and/or the correct info, so it might provide this function).

If I can only find something with a dive time display, I'm probably better off getting a second DC that could also be a backup to my first one.

 

[cmalinowski]

Hmm...this is all very interesting but I'm starting to think I had the wrong idea of what a bottom timer is. I thought it was nothing more than a stopwatch....so that you could time your stay at depth. I also thought that a countdown stopwatch would be the best way to go...diving to 115' and your max bottom time is 40 min? Set the countdown to 40 min, when you start your descent, hit the 'start' button.

If it could display the total dive time in addition to a countdown timer, that would be ideal....

I looked at the links above and did not find anything that was a basic timer or had a countdown timer. (The suunto D3 had one, but not in gauge mode, according to what's on the website. However, sometimes websites don't give you all and/or the correct info, so it might provide this function).

If I can only find something with a dive time display, I'm probably better off getting a second DC that could also be a backup to my first one.

Not sure I completely understand, but here's what I do.

I have the aladin tec. As I'm diving, the total dive time is displayed in mins/secs along with the depth. There is also a display in the bottom left of the scrn that you can switch between max depth, avg depth, and temp. When I begin my ascent, I press a button and the stopwatch starts anew. The total dive time is displayed inthe upper right corner (mins only) and the stopwatch is running where the total dive time was. So, I can easily time my ascent. If I want to reset it, it's a button push away.

Chris

 

[NJMike]

I guess my impression was that a bottom timer was used to tell a diver that it was time to ascend...not to actually time the ascent. So, for instance, say you were diving to 115', planning for a bottom time of 40 min, then a normal ascent to finish the dive. Once you started your descent, you would start a countdown timer (which was already set to start at 40:00), and when it got to zero, you would be alerted that it was time to start up.

An actual dive time display would do the same thing, you'd just have to do the math if you wanted to know how much time you had left, i.e. the display shows 27:30, so that leaves me 13:30...no, 12:30.

My DC shows ADT, so if I were to get something else that also showed ADT, as opposed to a stopwatch/countdown timer, then I'd be better off just getting another DC and having some redundancy on the computer calculations.

 

[Meng_Tze]

In simplest terms: most BT's tell you 'Bottom time', depth and sometimes also temperature and ascent rates. The time you spent below a certain depth (usually a few feet) includes descent, the time spent between descent and ascent (some call this actual BT) and the time spent ascending. Yes it does take a bit of tracking yourself, and if this is not something one can do easily, maybe a computer would be best where it does tell you how much time you have left at a certain depth, when/where to ascend and how long to stop.

A BT only tracks where you are (depth/time wise), not what to do and when