Forgetting to turn on computer before the dive

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Jcp2

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Thanks a lot! I didn't know that. I've seen that my computer (a Cressi Leonardo), according to the instruction manual, gets automatically into the dive program "DIVE AIR" when you reach a depth of 1.2 meters. But I don't know whether that means it'll turn itself on if it's turned off, or it needs to be already on and will get into the dive program if you are in the "DIVE SET" program instead.

I'll check in my next dive. I'll jump into the water with it off, will go down to 1.2 meters and see what happens. If it doesn't turn on automatically, I'll surface, turn it on and start the dive again.
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.
 

johndiver999

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I dive some old computers in a console. Oceanic or some other clones. There is an option where you can set it up for activation when wet or manual turn on. I always figured - hey if I screw up and forget to turn it on, it is better to have it running and thinking I am on air than to have northing. So I selected automatic on or whatever the hell they called it.

HOWEVER, this was a big problem. Water would get trapped in my console and maybe residual salt and the computer would not turn off in the garage. I would look at it three days after diving and the damn thing would be on and chewing through batteries. Once someone told me to deactivate the automatic on function, never had that problem again.
 

Jeff_O

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I dive some old computers in a console. Oceanic or some other clones. There is an option where you can set it up for activation when wet or manual turn on. I always figured - hey if I screw up and forget to turn it on, it is better to have it running and thinking I am on air than to have northing. So I selected automatic on or whatever the hell they called it.

HOWEVER, this was a big problem. Water would get trapped in my console and maybe residual salt and the computer would not turn off in the garage. I would look at it three days after diving and the damn thing would be on and chewing through batteries. Once someone told me to deactivate the automatic on function, never had that problem again.
Don't want to hijack the OP thread, but hopefully the computer could still be trusted. The button if no longer a momentary switch, then reverts to putting the batteries back in, by default, does it operate the same.
 

johndiver999

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Not sure I understand the question. I guess if you jump in with it off and it starts and you don't want to continue the dive with a setting of air, you could just get on the boat and wait 10 minutes until it allows you to set the proper nitrox mix?
 

Damselfish

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Some early dive computers didn’t turn on automatically when you went in, I’ve had a couple. But I wouldn’t expect that of anything not ancient, read your manual.

If you have a basic Nitrox computer it probably won’t let you change the N2 percentage once the dive has started. And some will reset to 21% after some period of time (looking at you Suunto) so you need to check. And you may not be able to change between Air and Nitrox modes once a series of dives has started, so usually best to leave it in Nitrox mode even if you only dive Nitrox sometimes.
 

Endler's

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I dive some old computers in a console. Oceanic or some other clones. There is an option where you can set it up for activation when wet or manual turn on...
I believe that all modern computers rely upon pressure to turn on at a certain depth (since this is the primary sensor). No need for wet contact switch (just another site for corrosion)! Under Pressure

1662937417102.png
 

Centrals

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I'll check in my next dive. I'll jump into the water with it off, will go down to 1.2 meters and see what happens. If it doesn't turn on automatically, I'll surface, turn it on and start the dive again.
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.
 

diver_pirate

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Actually, you still need to check it’s on prior to submerging as some computers will time out and turn off if no activity detected in a set period - my Teric does that.
Yes check for sure. My regimen is to set gas % when reg goes on tank. and turn on computer when "pools opened by crew after dive briefing then air on (all the way) and final pressure verrification. Oh, I always dive with 2 computers. (I don't trust electronics). At start of dive verify operation early during decent (5 meters / 15 feet). This has served me well.
 

BRT

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In the old days some single button pick computers (Sherwood the source) did not automatically turn on. You needed to push the button before you jumped in. It would not turn on at depth. You need to resurface to activate it. Worst thing was that once turned on at the surface it automatically turned off after a short delay if you did not start a dive. After having it turn itself off a few times while waiting to get in, I swapped to a computer that automatically turned itself on.

I would be surprised if there are modern dive computers that do not turn on automatically. Does anyone know of one?
Our Oceanics can be water activated but then they stay on so long as they are wet. In the tropics this may be a long time so I set them to not water activate.
 

CathyE

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My inexpensive computer turns on automatically at about 4 ft. It will also stay ‘live’ for a long time if the sensors are damp. After the days dives a couple of minutes with the hair dryer fixes this.
 
https://www.shearwater.com/products/teric/

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