Caves and transmitters.

[blac86]

Transmitters don't belong in caves. They are a metal-tp-metal connection which presents a failure point. They can break on hazards or walls. In general they arent used.

I dive sidemount and run my spgs down my tanks on 9 inch hoses. I was thinking what if I put my transmitters on those hoses (or even six inches) and put button spgs on my other hp port for backup?

Placing them dangled on hoses presents a solution to all the normal hazards, allows for seemless gas management with both main and backup computers, and the button spgs provide an analog backup to the Wireless ai.

 

[Doby45]

I run transmitters on my sidemount tanks that speak with my Perdix AI. I have 20 or so cave dives in this config with zero issues. I also am not doing exploratory dives that require the dive to carry on regardless of issues. Recreational level caves dives can be turned at any point and transmitters are a non-issue. If I was taking training of any type in an overhead I would pull the transmitters off and put my lollipops back on.

 

[Scott]

I have one cave buddy that used HP flex hoses and somehow routed the transmitter so it would lay between the first stage body and the DIN valve. Still allowed access to the handwheel on the valve and didn't look like it would get hung up.
Others I have seen just replace the transmitter with the SPG on a 6" hose, use some small bungee to hold it in place and call it.
Using a button SPG is an OK backup, but just how accurate they are is debatable.
I use them on deco bottles

 

[tbone1004]

what about the metal to metal connection are you talking about? I can 100% promise you that you won't be cutting a HP hose in the water because of an entanglement. That ain't gonna happen. The argument against metal to metal connections is for things you intend to get rid of from your body. I.e. lights, reels, deco bottles, etc. Not for individual components of regulator system. By your argument you can't use a tank valve because it is a metal to metal connection.

plenty of people use them in cave country including @The Chairman and personally if I'm going to use one in a cave because someone decides to give me a perdix AI with a pair of transmitters, they'll replace my SPG's completely and be mounted directly to my first stages. If the transmitter fails, it's no different than an SPG failing, turn the dive and head home. No need to have analog redundancy unless it's 100% critical that you complete the mission of that dive.
placing button gauges on them is only for convenience to verify that they're full without having your computer paired. There is no button gauge even close to accurate enough for cave diving so you aren't going to complete a dive on a button gauge. Furthermore if you are running your hoses a la razor, you can't have the transmitters down and lollipop gauges with the tank valves up. The forward mounting gauges will dig into the ground and puts them at risk for damage and more importantly it damages the cave. In places like Twin cave, that damage is permanent. Don't add to it.

the reason they aren't used is because up until like 6 months ago there wasn't a tech computer capable of handling multiple transmitters that wasn't ungodly expensive. Even now the transmitter cost is quite high. Has little to do with failure points or metal to metal connections.

 

[karstdvr]

I run transmitters on my sidemount tanks that speak with my Perdix AI. I have 20 or so cave dives in this config with zero issues. I also am not doing exploratory dives that require the dive to carry on regardless of issues. Recreational level caves dives can be turned at any point and transmitters are a non-issue. If I was taking training of any type in an overhead I would pull the transmitters off and put my lollipops back on.

I tend to think any dive in the overhead, without differentiation between between recreational and exploratory deserve the same level of respect. I have done exploratory dives with an equipment failure, and have not pushed on, but chosen for a safe exit; this includes a big exploratory push recently that got ended prematurely due to failures. I am minimalistic and like simplistic things with low failure. If I used electronic spgs in the cave environment, since they don't have a long history of success, I would tend toward conservatism with gas and profiles.

 

[The Chairman]

plenty of people use them in cave country including @The Chairman

I do.

 

[Capt Jim Wyatt]

Transmitters are fine in a cave environment if configured correctly, such as connected to a 6" HP hose and tucked down between the tanks. Just don't forget the install the spool into the hose.

 

[tbone1004]

@blac86 note that the post right above was from the recently retired training director of the nss-cds

 

[Doby45]

I tend to think any dive in the overhead, without differentiation between between recreational and exploratory deserve the same level of respect. I have done exploratory dives with an equipment failure, and have not pushed on, but chosen for a safe exit; this includes a big exploratory push recently that got ended prematurely due to failures. I am minimalistic and like simplistic things with low failure. If I used electronic spgs in the cave environment, since they don't have a long history of success, I would tend toward conservatism with gas and profiles.

Not at all am I saying to not respect a dive, any dive, so please do not imply that. But in the same token, I am currently Intro so I dive 1/6ths and lets say I go into the cave with my uber awesome mega transmitters and make it to my 1/6ths and they both die. I was headed out anyway and 5/6ths of my gas should be enough to get out, fix my transmitters, recalculate 1/6ths and go get me another dive in. By the time I get to Full Cave, I will have had enough dives on my system to be comfortable with it and it's dependability and carry on in the same fashion as I did at Intro. Transmitter dies, I turn the dive, regardless of where I am in my gas consumption. There in lies the difference in "recreational" cave diving and exploratory/task oriented cave diving. If I was doing that type of diving I would not use the transmitters simply due to the number of them I would need. Back gas, stages, deco and on and on. Ain't nobody got time for that!

 

[Capt Jim Wyatt]

Having a transmitter must not relieve the cave diver from having an analog spg as well.