Forgetting to turn on computer before the dive

[ElizaDoolittle]

I have the same computer and it turns on automatically provided the battery is still good. I usually turn it on myself to check that the gas is set correctly when gearing up to match what I have in the rental or my own tanks.

Thanks! It's great to know it. Well, I forgot to mention that I always use air, no nitrox. So all I do with the computer is turn it on at the dive center to check the battery is still OK prior to the dive (so as to have time to replace the battery if it's low), and then I turn it off because it can take a long time while I wait for everybody to get ready, get to the boat and get wherever we're diving, and in that way the battery will last longer. I usually turn it on again when we reach the dive site, and although I've never forgotten to do so, I wondered what would happen if I did.

Why do you want to do that?
If you do not trust it then get rid of it.
You are over thinking the issue.
Get another one(different brand) as back up.

I do trust my computer. What I do not trust is my memory. And I cannot get another one, I'm afraid.

 

[broncobowsher]

I had an Oceanic computer. Would not self turn on. Others have stated this before. There was a time out issue with the computer where I would not turn it on until ready to jump. I missed it once, or it timed out, I forget which. Was planned a 2-tank dive, started the dive, 100' to the sand. About half way down I checked and saw it was off. Tried to turn on in the water, not allowed.

My plan changed. We were both on our first dive. My buddy was not my computer. I stayed a little above him for the dive. At the end, I was done for the day. I got one dive in but passed on the second. I considered it safe, there was a computer watching over me. I cushioned the results by staying slightly above the computer.

 

[Centrals]

I do trust my computer. What I do not trust is my memory. And I cannot get another one, I'm afraid.

Why not?
Computer is not expensive.
Electronic does fail regularly and it is no fun at all if your computer fails during the dive. I have experienced it twice and dived with two dc since.

 

[ElizaDoolittle]

Why not?
Computer is not expensive.
Electronic does fail regularly and it is no fun at all if your computer fails during the dive. I have experienced it twice and dived with two dc since.

I mean I cannot get another memory for myself, which is what I don't trust. My computer is new and works perfectly well, but I just wondered what would happen if I forget to turn it on. And for that problem, having two computers wouldn't be the solution. If I forget to turn one off, I'll sure forget to turn the other one on, too.

 

[Belzelbub]

Thanks! It's great to know it. Well, I forgot to mention that I always use air, no nitrox.

In that case, no issues. Most dive computers made in the last 20 years (or more) have a feature that will entire dive mode automatically. Either by sensing pressure or wet contacts. The main concern with relying on this is that the mix may be different. Since you always dive air, no issue.

That said, check the manual for your device. Some used to enable a safety feature if the DC was auto activated. They would assume ~79% N2 for NDL/Deco calculations and 50% O2 for max depth and oxygen toxicity calculation. That’s obviously an impossible mix and would result in lower depths and shorter times than necessary. So, if your computer has the 50% O2 default, you may want to turn it off. Zero risk turning it off if you only dive air.

 

[hotdive global]

Normally the new model will turn on itself, but part of the diving check before descent is check your time(computer), if you really didn't turn it on with whatever reason, should consider the computer failure and do your safety stop and finish the dive

 

[boulderjohn]

Normally the new model will turn on itself, but part of the diving check before descent is check your time(computer), if you really didn't turn it on with whatever reason, should consider the computer failure and do your safety stop and finish the dive

About 15 years ago I suggested to PADI that there needs to be a change in the predive check to include the instruments being used to guide the dive rather than time. I suggested that for several reasons, and the by then nearly universal use of computers was key, and not just because computers replaced watches. A computer has several possible settings that could be inappropriate for the dive you are about to do.

I was spurred in my thinking by an event described in a ScubaBoard thread. A diver was planning to do his first dive on nitrox, and he set his computer accordingly. At the last minute, for some reason he decided to switch to his second dive tank, which was filled with air. He thus did his first dive on air, but with his computer set to nitrox, and, yes, he got bent.

I ran into another issue myself. That first computer I had was an air integrated console model--a Suunto. I later switched to a wrist computer and put the Suunto away. On a trip to Florida, I resurrected the Suunto to use primarily as an air pressure gauge but also as a backup to my wrist-mounted primary. Late in my first dive, my mind wandered, and I wondered when I had last used the Suunto. I realized it was in the Denver area, so it was likely still manually set for high altitude. I checked, and, yep, it already had me well into deco. Luckily, it didn't matter because my wrist computer had the right information.

PADI's response to me was enthusiastic. "Great idea! We will start working on a new mnemonic for it right away!" That was the last I ever heard from them about it.

 

[boulderjohn]

Normally the new model will turn on itself, but part of the diving check before descent is check your time(computer), if you really didn't turn it on with whatever reason, should consider the computer failure and do your safety stop and finish the dive

A few years ago I was teaching some students at a site where other instructors from my shop were teaching a variety of classes. I was asked to observe a divemaster candidate on one of his requirements, leading certified divers on a dive. I had never worked with that DMC before.

He started the dive with a careful 5-point descent, and when he reached "T" on the acronym, he pointed at his wrist, and all the other divers followed by pointing at their wrists. When we debriefed later, I asked him why he had everyone point at their wrists. He said that "T" stood for time, and they were all pointing to where a watch would have been if they had been wearing one. (No one had anything on their wrists.)

Why wasn't anyone, including him, wearing a watch? Well, because they were using computers instead. Where were the computers? On their consoles. Why didn't they look at the computers on their consoles instead of pointing at their wrists? Because looking at the computer would not tell them what time it was. Why did they need to know what time it was? He thought for a while, and he said that the logbooks ask what time the dive started. Why do they ask that? He was baffled. He had no idea why you needed to know the time at the beginning of the dive.

I then asked him about the "T" in the 5-point ascent. While underwater, they had all pointed to their wrists before ascending. I went through the "whys" again, and he eventually realized that the time difference between the start of the dive and the start of the ascent had only one purpose, and that was to allow the diver to use the dive tables to measure that dive and plan the next one. It had absolutely no function when people were using computers.

So I repeat that it is time to put the "T" in the 5-point descent and ascent away and teach people to check their computer settings instead.

 

[captain]

I also wear a watch and depth gauge along with a computer so no problem.

 

[NovaCane]

Thanks! It's great to know it. Well, I forgot to mention that I always use air, no nitrox. So all I do with the computer is turn it on at the dive center to check the battery is still OK prior to the dive (so as to have time to replace the battery if it's low), and then I turn it off because it can take a long time while I wait for everybody to get ready, get to the boat and get wherever we're diving, and in that way the battery will last longer. I usually turn it on again when we reach the dive site, and although I've never forgotten to do so, I wondered what would happen if I did.




I do trust my computer. What I do not trust is my memory. And I cannot get another one, I'm afraid.

I also have the same computer. Turning it on & off is not part of my routine, it does that on its own once you're below 5ft.