AI transmitter on stage cylinder?

[LFMarm]

For all you diving with transmitters, how many of have spare batteries and an SPG for when the transmitter is not working?

I carry a couple of batteries and 2 SPGs. In case of failure when gearing up, I swap to SPG and figure it out later.

 

[LFMarm]

You don't need this. Unless and until you are planning dives that require a gas switch, it is only necessary to check your pony pressure before beginning a dive. You won't be monitoring it during a dive, and it would be a distraction to do so. If you DO end up using the pony bottle during a dive it automatically means you are ending the dive as quickly as safely possible. You remaining gas supply should not be an issue. To the small extent that it is, you have the spg on the pony.

If there is a risk of losing a tank when checking pressure, I think time should be invested in tank handling before adding anything.

That being said, I fully agree with the recommendation. A pony bottle is for all purposes the same as a bailout bottle for CC — pressure checking is done at the beginning to confirm you have what you planned for (after that you close the valve and just pay attention to any bubbling) and in case of emergency. In either situation, the benefits of AI are very little compared to SPGs.

 

[chthonicly]

I am a recreational diver now heading toward ‘accelerated deco’ training which involves a stage cylinder with Nitrox.

I have an AI transmitter for my back gas and was wondering, for those that also use a transmitter, how many people add another for their stage cylinder (as well as the SPG)?

Cheers
Jonathan

It's a bit controversial. Some people don't trust AI no matter what, some people want the simplest thing, some people want team resources which are usable by the whole team, some people want the newest shiny thing.

I use the tx on my stage if I'm using it basically to extend the dive (as in OC stage cave dives). I don't bother with a tx on deco bottles (but I normally have short deco).

I have had zero issues with my shearwater reconnecting to the transmitter when i pick up the stage again if I've dropped it at some point during the dive. I also like getting the stats from when I'm breathing the stage, which can be for long periods of time. If you like AI and have the budget for it, try it both ways and decide which is right for you.

 

[bipolarbear]

I use the Garmin transmitters. They've been mostly reliable, although not perfect.

I have a transmitter on the right post of my doubles, and a standard SPG coming off the left post. Running both, although creating an additional potential point of failure, has the benefit of alerting me to the unlikely situation where the isolator valve has been inadvertently closed on my doubles (in which case my Garmin dive computer would show the pressure in my twinset decreasing, but my SPG coming off my left post would remain static).

For deco tanks, I just have a small SPG on a short hose bent back on itself. SPGs are still more reliable than transmitters, and these things get thrown around a lot. I don't have enough confidence in the transmitters to remove the SPG, and I don't like increasing the additional point of failure of running both a transmitter and an SPG.

For bottom stages, I include both the SPG and a transmitter. This is because on some dives I descend on an AL80 stage, suck the entire thing dry (often at depth, ~60m) before changing over to backgas. I like being able to monitor the gas status of the stage on my wrist, as I'm often swapping in the single-digits bar range. The additional risk of failure due to leaks etc is manageable as I am breathing this cylinder down entirely at the start of the dive.

For rebreather bailout, I just use SPGs. These should never really be used, and an SPG does the job perfectly well.

 

[Divin'Papaw]

For all you diving with transmitters, how many of have spare batteries and an SPG for when the transmitter is not working?

I keep a spare Tx and SPG in my boat backpack. I can swap to either in about 3 minutes.

 

[Divin'Papaw]

That being said, I fully agree with the recommendation. A pony bottle is for all purposes the same as a bailout bottle for CC — pressure checking is done at the beginning to confirm you have what you planned for (after that you close the valve and just pay attention to any bubbling) and in case of emergency. In either situation, the benefits of AI are very little compared to SPGs.

For me, having a Tx on my pony is about readability and ease of checking the pressure. Long gone are the days I can read a button gauge without reading glasses. Having it on my computers is just far easier to read for me.

Is it essential? Certainly not. But it’s nice to have and I can afford it. It was an easy decision and I’m glad it’s there.

 

[halocline]

I am a recreational diver now heading toward ‘accelerated deco’ training which involves a stage cylinder with Nitrox.

I have an AI transmitter for my back gas and was wondering, for those that also use a transmitter, how many people add another for their stage cylinder (as well as the SPG)?

Cheers
Jonathan

I use SPGs on all bottles and no AI. I’m a Luddite. I do, like an everyone else, use 2 computers for any technical diving.

You said you’re learning to use a stage for accelerated deco. I’m not entirely clear on what you are saying, are you carrying a stage to extend your dive or are you carrying deco gas. Not that it might matter, but in the dives that I do I typically drop the stage (cave dives) and pick it up on the way out. That means it will lose sync. Since I’ve never used AI I don’t know how much of an issue this is in terms of reliably re-syncing when you pick it up or battery usage when it’s dropped.

For deco gas I only use a button SPG. You just need to know that you have enough for your plan at the beginning of the dive, you don’t need to constantly monitor your usage. And at least theoretically, button gauges provide less fuel for an O2 fire. I’m a little bit obsessed with keeping combustibles out of the HP O2 path; I use a 1st stage that has a very low volume in the HP chamber and only the DIN retainer o-rings, and the tiny seat, are exposed to HP gas.

 

[VikingDives]

I'm on team button gauge, but frankly, I'm not even sure that's necessary. When you're doing deco, you should know how much you need etc. etc. as mentioned above. I don't trust button gauges to give me more than a picture of what a real pressure gauge is telling me and once you're underwater, my view is you have what you have. Proper deco planning with contingencies should ensure that you have more than enough gas when you have problems.

OTOH, I don't have a strong feeling against using transmitters or full size gauges. If it makes you feel better to see how much gas you have, I don't see anything wrong with feeling better about what you're diving.

 

[Manatee Diver]

I looked at it after SRI updated their firmware to allow four transmitters. I run transmitters only on my sidemount tanks.

I declined to do it for a few reasons. The first is that I couldn't figure out how to effectively still use a SPG. I feel a SPG is still required as stages bottles are a team resource that you might exchange around they will still need to be able to see the gas remaining; also my gas switch procedure relies on a SPG as verification that the valve I am manipulating is attached to the second stage I am holding, the five second refresh time is too slow.

The next reason is that it clutters up my main row on my computers, since I am transmitters only on my tanks I have an entire slot dedicated to those transmitters, I would have to give up another slot to the other transmitters. And the computer will complain when they are out of range when I drop them and continue into the cave.

The final reason is that I have five stage/deco regs that I interchange all the time (if I have an issue I just grab another), and SRI doesn't support seven transmitters while even if it did I have better uses for the at least $1,500 that would cost.

 

[SelfDiver]

If the SPG or AI was mission critical equipment, we would require two.
There is no reason to go to "emergency" mode just because an SPG fails. The tank has the same gas and quantity.
Try doing a dive where you cover your stage tank SPG. Nothing bad happens.
I still have an SPG that is always off by 50 bar. Perfectly usable in a pinch.