I just hijacked a FB thread in one of the JJ groups where someone was posting about their adapter for using a wireless transmitter and the original SPGs. I realized that while this discussion was interesting, it would be better here as a separate thread.
I have heard experienced CCR divers say that they never check their tank pressure during a dive, so they just use button gauges. I have heard other divers say that they want to continually monitor their tank pressure through a dive computer. I'm interested in the arguments for different approaches. Here is what I posted. For those who haven't seen a JJ, the HP hoses are routed between the wing and the back mounted counterlungs, with the SPGs tucked in the back of the unit, in front of the valves, where they can be pulled out and then restowed. I didn't like the stock velcro hose keeper on the wing, so I rigged a small bungee loop on the backplate to keep them in place after pulling them out for a check.
One of the nice things about the JJ is that it's so simple and clean, with minimal failure points. I really like having the SPGs routed where they are since they are out of the way. I don't see the point in putting two transmitters into the crowded space under the can, especially since they are more vulnerable than on an upright OC tank (CCR tanks occasionally slip down).
Other than a boom drill (or a real boom), when do you guys check your gas during a dive? The SPGs are pretty easy to check in the very rare case that the information will change your failure management.
Dil generally not an issue, but if you can't add dil and you check your tank valve and inline shutoff and they are open, then bail out or possibly plug in offboard if you are for some reason actually out of dil and you still need it. You are ascending anyway, unless you are in a cave with up and down exits.
You can check your SPG if you have a boom and want to confirm O2 and stay on the loop for ascent. If you have actually run out of O2 without a boom, that's a planning problem. But if you can't maintain your PO2, it's either OOG, O2 tank valve shut, or some sort of downstream failure (e.g first stage). In any case, you need to plug in offboard O2, bail out or go to SCR mode, right?
I know that more information is good, but since with SPGs you have the info in the rare case that you need it, why add cost, complexity and failure points? It's not like OC where you have a turn pressure that you need to watch for...
I have heard experienced CCR divers say that they never check their tank pressure during a dive, so they just use button gauges. I have heard other divers say that they want to continually monitor their tank pressure through a dive computer. I'm interested in the arguments for different approaches. Here is what I posted. For those who haven't seen a JJ, the HP hoses are routed between the wing and the back mounted counterlungs, with the SPGs tucked in the back of the unit, in front of the valves, where they can be pulled out and then restowed. I didn't like the stock velcro hose keeper on the wing, so I rigged a small bungee loop on the backplate to keep them in place after pulling them out for a check.
One of the nice things about the JJ is that it's so simple and clean, with minimal failure points. I really like having the SPGs routed where they are since they are out of the way. I don't see the point in putting two transmitters into the crowded space under the can, especially since they are more vulnerable than on an upright OC tank (CCR tanks occasionally slip down).
Other than a boom drill (or a real boom), when do you guys check your gas during a dive? The SPGs are pretty easy to check in the very rare case that the information will change your failure management.
Dil generally not an issue, but if you can't add dil and you check your tank valve and inline shutoff and they are open, then bail out or possibly plug in offboard if you are for some reason actually out of dil and you still need it. You are ascending anyway, unless you are in a cave with up and down exits.
You can check your SPG if you have a boom and want to confirm O2 and stay on the loop for ascent. If you have actually run out of O2 without a boom, that's a planning problem. But if you can't maintain your PO2, it's either OOG, O2 tank valve shut, or some sort of downstream failure (e.g first stage). In any case, you need to plug in offboard O2, bail out or go to SCR mode, right?
I know that more information is good, but since with SPGs you have the info in the rare case that you need it, why add cost, complexity and failure points? It's not like OC where you have a turn pressure that you need to watch for...