Two divers critical - Hawaii

[Superlyte27]

1. Not sure what you mean by sleep mode, but the discussion so far about this case was about how the unit was in surface mode. In surface mode it continually reads and displays PO2, 4 places. Do you mean someone doing a prebreathe without the unit being powered up at all...?

2. Stick one of those AI transmitters that are so popular these days on your O2 first stage. Now you have data to tell if the valve is on with no wires, no problem swapping tanks.

Or, you could just actually do the preflight checklist. Tell yourself “if I’m gonna dive this thing, I’m committing to that checklist. Before every dive.”

So, you can have the unit powered up, but not in dive mode or surface mode. It’s actually asleep. Batteries are on, but nothing else is. Neither handset is functioning, but HUD and BUDDY light do a slight blinking thing to let you know the unit is under power.

 

[doctormike]

So, you can have the unit powered up, but not in dive mode or surface mode. It’s actually asleep. Batteries are on, but nothing else is. Neither handset is functioning, but HUD and BUDDY light do a slight blinking thing to let you know the unit is under power.

Gotcha. When would you use that as opposed to just turning it off? Are the sensors still being read?

 

[Superlyte27]

No, they are not. And both handsets are blank.
So, let’s say I build the rebreather at home, the night before a dive. I’ve done my calibration, and positive and negative. The rebreather is built and ready to go. The batteries are internal. The only way to disconnect them is to break the loop. So, the lights blink to let you know that the batteries are online. But until I power up the handsets, it’s just sleeping.

At the end of the dive, I’ll turn off the system, (all handsets, computers, etc) but the batteries are still online. I’m diving the unit the next day, so I don’t want to break the loops since I still have tons of scrubber duration. The buddy light and hud will blink for months (until both batteries are depleted)

I tested this (not purposely) when my truck was underwater for a couple of weeks and took another couple of weeks to get into the locked truck bed with the Liberty inside.

 

[doctormike]

No, they are not. And both handsets are blank.
So, let’s say I build the rebreather at home, the night before a dive. I’ve done my calibration, and positive and negative. The rebreather is built and ready to go. The batteries are internal. The only way to disconnect them is to break the loop. So, the lights blink to let you know that the batteries are online. But until I power up the handsets, it’s just sleeping.

At the end of the dive, I’ll turn off the system, (all handsets, computers, etc) but the batteries are still online. I’m diving the unit the next day, so I don’t want to break the loops since I still have tons of scrubber duration. The buddy light and hud will blink for months (until both batteries are depleted)

I tested this (not purposely) when my truck was underwater for a couple of weeks and took another couple of weeks to get into the locked truck bed with the Liberty inside.

Aha... So no controller switch. Gotcha.

 

[Superlyte27]

I’m curious as to whether the system would power on if in sleep mode by a wet activation. I’ll try that next dive.

 

[pepperbelly]

Would it be feasible to have the O2 have to be on in order to power up the unit?

 

[Basking Ridge Diver]

Would it be feasible to have the O2 have to be on in order to power up the unit?

Everything is feasible. But at what price, weight and complexity are you going to stop making things foolproof? That to me is the question.

Because right now brand new units are very pricey, weigh about 75 lbs and how much more complex (considering things will break and need to be serviced) do we want to make a RB? I have tried one and they are fun - but at what price am I willing to get in the market? Making it foolproof will increase my barrier to entry...

 

[fsardone]

Would it be feasible to have the O2 have to be on in order to power up the unit?

Look, for whatever foolproof system you implement nature will just deliver a better fool.

I fly high performance aircraft, we do training, simulators years of training and we mess up.
Human factors still is 80% of the mishaps. We spend truckloads of miney in training.

Many (if not most) recreational divers do not commit enough brainpower, will and training to achieve a sufficient safety level. When you start using complex equipment and you ignore their failing modes you run the risk of ignoring a deadly failure mode.

So to go back to you question the answer would be yes and you would end up with people jumping in with electronics off and oxygen shut.
The auto power on feature was created because people were jumping in with electronics off.

Cheers

 

[Superlyte27]

Look, for whatever foolproof system you implement nature will just deliver a better fool.

Dude, that’s awesome. I’m adding it to my signature.

 

[KenGordon]

Would it be feasible to have the O2 have to be on in order to power up the unit?

In this case that would not have saved him. It was switched off.

Also, there are times you want to switch it on with no o2 supplied. For example, to let the airport security people see it is a real thing and not a bomb.

The key is training and proper understanding of the risk. Users need to understand that they are part of the system and that they are fallible. Then they need to take steps to manage that. I know I make mistakse all the time, people who claim not to worry me.