Bottom Timer vs Dive Computer

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MT_Dweller

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Bozeman, MT
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Greetings All....So what are the main differences between a Bottom Timer and a Dive Computer? I've done a search and can not find a simple answer to this question. Is a BT a basic DC without all the functionality, or are they two names for the same thing? For instance the xDeep Black BT is considered a BT, but they call it a DC when you upgrade the software to the EANx version. Am I overthinking things here?
 
The term "bottom timer" encompasses anything that times how long your dive is. A wristwatch is a type of "bottom timer." A dive computer can serve as a bottom timer, too. Some dive computers have a "gauge mode" that disables the computation feature and just displays depth and time. But that's not necessary to turn it into a bottom timer--you could just ignore everything but elapsed time and, voila, it's a bottom timer. To put it another way, all dive computers are bottom timers, but not all bottom timers are dive computers.
 
Generally you use a bottom timer (or a computer in gauge mode or just ignoring what it is telling you about deco) when you are using a precomputed table for your dive. This is mostly but not exclusively used in tech diving.

Unless your instructor has explicitly told you that you need a bottom timer for a course you almost certainly want a full blown dive computer.
 
If people are diving tables, whether for dives within the "recreational" range, or for technical diving, the only information they need is how deep they are and have been, and for how long. That's what a bottom timer gives them. For managing decompression status, someone diving a bottom timer needs to have a separate mechanism to do it.

Dive computers contain a program that is constantly calculating nitrogen loading, according to the model used by the manufacturer. They therefore display not only depth and time, but also decompression status.

Diving with just a bottom timer requires very careful attention to your dive profile, and quite a bit of discipline. The novice, or casual diver is probably better off with a computer which will pay attention to what they are doing, even if they don't :)
 
Simply put, with a bottom timer you need to know tables, with a computer you do not.

If you are doing multilevel dives with the bottom timer & depth gauge, pick up an old Wheel to help you out while doing the calculations.


Bob
 
If you are doing multilevel dives with the bottom timer & depth gauge, pick up an old Wheel to help you out while doing the calculations.
Bob

With use of the tables you use 10 min SIT for the multilevel dives in between your depths and it does not require a wheel.
 
Greetings All....So what are the main differences between a Bottom Timer and a Dive Computer? I've done a search and can not find a simple answer to this question. Is a BT a basic DC without all the functionality, or are they two names for the same thing? For instance the xDeep Black BT is considered a BT, but they call it a DC when you upgrade the software to the EANx version. Am I overthinking things here?

A bottom timer will tell you depth (max) and time in the water. Some will give ascent info. A depth timer may or may not be a computer. My first gauge was a depth gauge / bottom timer. I used it for square and multi-level dives.

Some of the more modern computers can be anything based on the software. So a BT can be come a dive computer.
 

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