Okay, since there was some push to show we do just do fun, dives, I figured I would post a short summary of two cave dives where discussing the logistics might be useful to some of you. Plus, it has been dead in ths forum.
First Dive. I can't really give site names but I think this one was near Nahoch. Dive time 3 hours, average depth 27'. Two stages and AL80 back gas. Two many team. The first stage was dropped at 1/2 + 100 and the second stage was to be turned at 1/2. I turned the dive before hitting halves on the second stage at 100 minutes because the swim out was going to get ridiculous. (I think rjack was complaning about two swim dives in Mayan and I had a hard time not making fun of him in that thread so I will do it here.) We were planning on using 1/4 of our total gas for penetration which was plenty to swim out in these circumstance. On a dive of this distance, while this is pretty conservative, I would be hesitant to push gas any further. Technically, you could do the same dive with thirds using one stage, but then you start to lose flexibility and given the distance lugging an extra stage, even though swimming, is worth it.
Second Dive. Nahoch to the Blue Abyss. Triple Stage and AL80 back. Two long body Gavins per team member. Three man team. Dive time 185 minutes, max depth of 80' and average depth of 19'. Plan, burn first scooter for 40 minutes, and switch to second. Switch first stage at 1/2 + 100 and go to second stage. Drop all stages and scooters at restriction to Blue Abyss. Third stage is bailout plus assuming everything is going smoothly when we exit the restriciton, gives us gas to recalc and explore additional tunnel based on how much back gas is used going to the Blue Abyss. Actual dive, swithced scooters at 40 minutes of burn time (45 or so bottom time) and dropped first stage at 50-60 minutes. Don't remember exactly. Dropped remaining two stages and both scooters at 70 minutes so it had about 20+ minutes of remaining penetration burn time.
Went to back gas to see the Blue Abyss. I had never actually been here before. Scootering Nahoch, which I have done a lot is spectacular. And, getting to see the cave go from a fairly restricted area to a pit that drops to 220 with a tanic section on the ceiling at 5-10 feet, and an indistinct halocline around 40 feet or so was really cool. But the trip there an back is actually much prettier. Due to its fame the restricted area leading to the Abyss is far more beat up than similiar cave that is this far out but less well known in the area. We got back to the stages with over 2k in our back gas.
Then plan was to go to the full stage and explore the line we were on. However, I had well over 2k in my second stage so I went to it and decided to recalc to 1/2 of what was left + a few hundred PSI. Don't remember exactly now. We picked up the same scooter and took off. We turned slightly after this because one team member started having ear troubles. I ended up using the stage I was on for the entire exit so actual gas usage was less than 160cuft out of a total of 400cuft. If we had executed the entire dive as planned it would have been a max of 200 cuft resulting in a reserve of 50% i.e. enough to do the whole dive over again. Since we were turning at scooter burn time, we really wouldn't have used more than about 20cf more of gas. So max gas usage would have involved using up to 1/4 of the available gas for penetration. But, we would have never been at max distance. So, it would have taken less gas to exit at any point i.e. the actual reserve in gas was always better than 1/4, more like 1/5+. And there was technically a bailout cenote around 5k (but a very poor option that was not actually part of the planning).
First Dive. I can't really give site names but I think this one was near Nahoch. Dive time 3 hours, average depth 27'. Two stages and AL80 back gas. Two many team. The first stage was dropped at 1/2 + 100 and the second stage was to be turned at 1/2. I turned the dive before hitting halves on the second stage at 100 minutes because the swim out was going to get ridiculous. (I think rjack was complaning about two swim dives in Mayan and I had a hard time not making fun of him in that thread so I will do it here.) We were planning on using 1/4 of our total gas for penetration which was plenty to swim out in these circumstance. On a dive of this distance, while this is pretty conservative, I would be hesitant to push gas any further. Technically, you could do the same dive with thirds using one stage, but then you start to lose flexibility and given the distance lugging an extra stage, even though swimming, is worth it.
Second Dive. Nahoch to the Blue Abyss. Triple Stage and AL80 back. Two long body Gavins per team member. Three man team. Dive time 185 minutes, max depth of 80' and average depth of 19'. Plan, burn first scooter for 40 minutes, and switch to second. Switch first stage at 1/2 + 100 and go to second stage. Drop all stages and scooters at restriction to Blue Abyss. Third stage is bailout plus assuming everything is going smoothly when we exit the restriciton, gives us gas to recalc and explore additional tunnel based on how much back gas is used going to the Blue Abyss. Actual dive, swithced scooters at 40 minutes of burn time (45 or so bottom time) and dropped first stage at 50-60 minutes. Don't remember exactly. Dropped remaining two stages and both scooters at 70 minutes so it had about 20+ minutes of remaining penetration burn time.
Went to back gas to see the Blue Abyss. I had never actually been here before. Scootering Nahoch, which I have done a lot is spectacular. And, getting to see the cave go from a fairly restricted area to a pit that drops to 220 with a tanic section on the ceiling at 5-10 feet, and an indistinct halocline around 40 feet or so was really cool. But the trip there an back is actually much prettier. Due to its fame the restricted area leading to the Abyss is far more beat up than similiar cave that is this far out but less well known in the area. We got back to the stages with over 2k in our back gas.
Then plan was to go to the full stage and explore the line we were on. However, I had well over 2k in my second stage so I went to it and decided to recalc to 1/2 of what was left + a few hundred PSI. Don't remember exactly now. We picked up the same scooter and took off. We turned slightly after this because one team member started having ear troubles. I ended up using the stage I was on for the entire exit so actual gas usage was less than 160cuft out of a total of 400cuft. If we had executed the entire dive as planned it would have been a max of 200 cuft resulting in a reserve of 50% i.e. enough to do the whole dive over again. Since we were turning at scooter burn time, we really wouldn't have used more than about 20cf more of gas. So max gas usage would have involved using up to 1/4 of the available gas for penetration. But, we would have never been at max distance. So, it would have taken less gas to exit at any point i.e. the actual reserve in gas was always better than 1/4, more like 1/5+. And there was technically a bailout cenote around 5k (but a very poor option that was not actually part of the planning).
