Ok...so I'll be the freak here. I dive primarily solo and consider my diving solo even with a buddy. I dive a back mount 19cf pony. AI only for my primary gas and a 2in SPG integrated into my pony reg.
SPG or not
- Thread starter Caribbeansoul74
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Did you change this after you tried to kill yourself, but failed?Ok...so I'll be the freak here. I dive primarily solo and consider my diving solo even with a buddy. I dive a back mount 19cf pony. AI only for my primary gas and a 2in SPG integrated into my pony reg.
Yep...... also have my pony 2nd necklaced now.Did you change this after you tried to kill yourself, but failed?
halocline
Contributor
If your life depends on your spg working, you are not diving safely. Didn’t you learn to deal with equipment failures in your OW class?
Sorry to be curt, but this ‘your life depends on your gear’ bit is really old.
Belzelbub
Contributor
Hmm. I trust a lot of things designed by engineers. Mechanical devices have moving parts. Moving parts can, and do, fail from time to time. The transmitters can also fail. The difference is how. Barring dead batteries (user error) electronic transmitters (and electronics in general) often fail on initial startup and fail spectacularly. Failure is very clear to the user. Never had a transmitter fail in the water, only ever on initial power up. Can't say the same for SPG.
But...
Exactly. A transmitter or SPG failure should not be life threatening. It's an annoyance at best, as you should end the dive. But, if you've been checking periodically, you should have a good feel for approximately how much you have left.
If a transmitter fails in the water you won't get an indication of having more gas than you think you do. I've definitely had SPGs fail in a way where you might.
I'd be curious to see a display mode which showed time since last connection and pressure at that time.
I'd be curious to see a display mode which showed time since last connection and pressure at that time.
Well, in nine pages, I haven't seen the one valid reason I have for having both.
We've done the reliability thing vs the extra point of failure argument. We've strayed into computer algorithm discussions.
But the one time I was glad I had a button gauge at the end of the hose that holds a splitter with my transmitter and the button gauge, was on a panga in the Philippines. Getting gear up the tiny plank from the rocky shore into the boat was an invitation to disaster in the mild surf, so the crew insisted on attaching our tanks on shore and carrying our gear on board for us (after which I'd inevitably rearrange things).
First, the crew couldn't tell that they'd attached a full tank if all you had was a transmitter to look at. But for me, since my wetsuit was folded down around my waist in the heat until we got closer to the dive site, my computer was in my little dry bag with my towel. Not once, but twice during the trip, in the time it took between attaching my tank and completion of loading, I discovered a loss of 400-1000 psi from either a poor fill or a leaking tank o-ring, with the valve having been left on.
The only way I knew was a quick peek at my button gauge on the way to my seat. Alternative? Wearing my computer while boarding, removing it and stowing it while I slipped into my wetsuit sleeves (while not dropping it overboard) and then putting it back on again.
I'll take the extra failure point. If my cheap gauge is wrong, I'm not paying attention to it anyway, barring that rare transmitter failure.
We've done the reliability thing vs the extra point of failure argument. We've strayed into computer algorithm discussions.
But the one time I was glad I had a button gauge at the end of the hose that holds a splitter with my transmitter and the button gauge, was on a panga in the Philippines. Getting gear up the tiny plank from the rocky shore into the boat was an invitation to disaster in the mild surf, so the crew insisted on attaching our tanks on shore and carrying our gear on board for us (after which I'd inevitably rearrange things).
First, the crew couldn't tell that they'd attached a full tank if all you had was a transmitter to look at. But for me, since my wetsuit was folded down around my waist in the heat until we got closer to the dive site, my computer was in my little dry bag with my towel. Not once, but twice during the trip, in the time it took between attaching my tank and completion of loading, I discovered a loss of 400-1000 psi from either a poor fill or a leaking tank o-ring, with the valve having been left on.
The only way I knew was a quick peek at my button gauge on the way to my seat. Alternative? Wearing my computer while boarding, removing it and stowing it while I slipped into my wetsuit sleeves (while not dropping it overboard) and then putting it back on again.
I'll take the extra failure point. If my cheap gauge is wrong, I'm not paying attention to it anyway, barring that rare transmitter failure.
Eric Sedletzky
Contributor
I saw some comments to not have either, just run out of air. I have done that, on purpose in the shallows just to see what it's like.
If someone want's to go old school for one reason or another whether it be going retro as a fashion statement or perhaps you have a deep paranoia of both AI and SPG's and all the failure horrors that "might" occur, may I suggest that you use a J valve, or at the very least use an unbalanced first and second stage like a MK2/ R190 or similar, or both.
At least you will get an integrated resistance as the air supply runs down, the reg will slowly begin to breath stiffer and you will get plenty of warning before you completely run out. I would strongly recommend this setup for someone who routinely forgets to look at their AI or SPG. I would say there are probably 20 to 30 good breaths from the time it's pretty noticable to where you're sucking a marble through a garden hose. Once I was testing this in the shallows and using my MK2 and breathing off the R190 and it was to the point where I could barely get another breath. Then I switched to my G200B and it breathed like I had a full tank. Pretty scary actually how those scubapro pneumatically balanced second stages will work on almost nothing. This is why people get that one last breath and then dinner plate eyes!!
A few breaths later it suddenly came to an end and I popped my head up by the beach. BTW, the SPG read zero quite a ways back in the story.
The problem with a J valve is sometimes when you get to this point you reach to pull the rod and realize it's already down! dinner plate eyes!
I guess that was the big faux pas back in the day.
If someone want's to go old school for one reason or another whether it be going retro as a fashion statement or perhaps you have a deep paranoia of both AI and SPG's and all the failure horrors that "might" occur, may I suggest that you use a J valve, or at the very least use an unbalanced first and second stage like a MK2/ R190 or similar, or both.
At least you will get an integrated resistance as the air supply runs down, the reg will slowly begin to breath stiffer and you will get plenty of warning before you completely run out. I would strongly recommend this setup for someone who routinely forgets to look at their AI or SPG. I would say there are probably 20 to 30 good breaths from the time it's pretty noticable to where you're sucking a marble through a garden hose. Once I was testing this in the shallows and using my MK2 and breathing off the R190 and it was to the point where I could barely get another breath. Then I switched to my G200B and it breathed like I had a full tank. Pretty scary actually how those scubapro pneumatically balanced second stages will work on almost nothing. This is why people get that one last breath and then dinner plate eyes!!
A few breaths later it suddenly came to an end and I popped my head up by the beach. BTW, the SPG read zero quite a ways back in the story.
The problem with a J valve is sometimes when you get to this point you reach to pull the rod and realize it's already down!
dinner plate eyes!I guess that was the big faux pas back in the day.
Eric Sedletzky
Contributor
And as an analogy to this, let's say you're headed out on a road trip with a full tank of gas. You know from prior experience that you get about 300 miles give or take on a tank.
100 miles into the trip your gas gauge quits. Do you freak out and pull over and get towed home, or do you casually go on and find a gas station to top up knowing that you just reset to 300 miles of range, and continue on to your destination?
With air supply, shouldn't someone have an idea of what they use, how long they have been down and at what depth most of the dive was? Or are most people so used to just running their dives based on instrumentation alone and have no clue about their situational awareness?
Here's a fun excercise for those who dare.
Cover your SPG in duct tape and go do a dive based on what you know about depth time breathing rate and the size of your tank. You might be surprised at how close you can estimate your remaining air. When you are a ways into your dive nearing what you believe is your ending time pull the tape off and see where you're at.
Exactly. I have a miniSPG mounted on my first stage in the second HP port. Super handy to see if the tank is full without firing up one of my AI computers. Especially nice on liveaboards where they come around and fill your tank with a whip, between dives. The DMs love it....no guessing about whether the tank has been filled or not. Yes, I carry an SPG in my save-a-dive kit....but I carry a spare transmitter, too!
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