Stage planning in caves

[Mike Edmonston]

Yes, there is such a cave in Missouri that does that. It has a short tunnel at 45' right after the cavern zone. Then there is a vertical silo to 150' and a tunnel that bounces around between 130'-160' for a while. Water temp is about 50f. They say the river ices over in the winter time, so you can also do an ice dive

I should be up to dive Cannonball in Feb or March. Are you pretty close?

 

[rjack321]

I think you have lost something in the explanation. Carrying enough back gas for a failure of all stages and deco is often not practical.

The earlier posts suggested that was the case. I sorta knew it wouldn't be. But wanted to make it more explicit.

But, a great general rule of thumb is that if a complex dive goes well, you should have enough gas on you at the exit to do the whole thing again (i.e. half the gas or slightly less but with fewer bottles). It is the concept of building a bigger reserve gas cushion than thirds as the complexity of the dive increases that is important.

Thanks, that's helpful to learn how the "cave diver thinks".

Also, deep stops are arguable done better in caves. But, it isn't as regimented since more often than not the profile of the cave on the exit provides you with a significant portion of the deep stops that need to be done. For instance, if you are doing a dive to 220 and then have a 1,000' ride back at 120, you are going to spend far less time getting to your O2 bottle from 120 than you would if you started a direct open water ascent from 220.

In my experience having a big wad of 'deep' deco time does not allow me to trim anything from shallower stops. In fact I seem to on-gas at EAN50 60 and 70ft stops just about as much as I off-gas. (offgas He, ongas N2 I suspect) So while I can see some trimming of intermediate depth deep stops, I would be hesitant to modify my profiles substantially from what I currently do in OW. Tiered deep stops based on time and depth with the time increasing up to the gas switch. If in your example you were on 35/25 or something I could see that being different than backgas though.