Day 10 Cave Diver Course
Location: Buton Tengah, Muna island.
Cave: Goa La Ode Panu
Dive time: 124 minutes
Cumulated Dive time:1458 minutes
Gas Recalculation and Lost Diver.
Gas Recalculation? What the heck? Why would I need to recalculate my turn
It is pretty straightforward, starting the dive I have a set amount of available gas, I use 1/3 to go in 1/3 to go out and 1/3 for who knows what may happen in this cave. This scenario works pretty well in a straight-line cave: going in, turning back and going out. Some caves are designed a little bit different and you have several lines starting close by the entry.
Let’s do a little bit of math:
You start the dive with 210 bars in the left tank and 210 bars in the right tanks, or more simply 210/210. One third of 210 is 70. So, I can use 70 bars on each tank to go in. My turn pressure is then 140/140. This is not rocket science. (By the way did I already say that diving on 1/3rd is far from being ideal in many cases ?)
Now let’s say that, in fact, you hit the end of the tunnel at 190/190 it means that you will be back to the entry with 170/170. Bummer you still have quite a lot of gas, it could be nice to be able to “recalculate” your new turn pressure and go again. That would basically work that way if you could start again a new dive from the entry point. But what if the secondary branch is not exactly at the entry of the cave? That’s where the calculation got a little bit trickier. You need to account for the gas you need to exit from the beginning of this new branch, and at least double that to be able to exit safely.
Of course, this is not a tool to be able to suck up all your gas until you reach the exit with 1 bar in your tank. But at least you can get a little bit more out of those tanks and enjoy more of this incredible scenario.
I won’t give you here the full calculation but that was just a glimpse to illustrate what do we mean with “gas recalculation”. For that you would of course need some good underwater communication skills, good gas awareness, and precise information about how much gas you need to exit from the actual point where you’re recalculating (remember those notes from yesterday? they come handy at this particular point).
During today’s dive indeed students had to record information about the cave and perform recalculation at various point. Looks easier than it is.
Once again recalculation can be a useful tool to extend your bottom time but should be treated with a lot of respect and only once you gain experiences and knowledge of the actual cave. The more you do it, the more you are prone to and an error could be proven fatal. Remember that the less gas you have in your tanks, the less gas you have to breath and survive, plain science. So do not recalculate until your calculus reach zero, keeps a very large buffer or baseline! Or even better do not do it if you’re not sure and confident about what you’re doing. Extending your time underwater is not the only point of this skills, it will be also very useful for lost buddy scenario.
A good cave dive is a cave dive with good buddies (said the solo diver). Buddies are here to have your back. They can back you up when you screw big time, they are people that we like to share our dives with. They must always stay close by to you, double check your decisions and make sure you’re in a good shape to dive.
Unfortunately, things do not always happen that way. Buddies can be distracted, make their own mistakes, loss their awareness for a short time and suddenly goes missing. You were a team of three, and suddenly you’re only two. Number 3 is nowhere to be found.
You look around quickly, but not too much so you not getting disoriented but still can’t see him.
Now starts the lost buddy procedure.
First thing first, don’t get yourself lost too. Drop an arrow on the line, obviously pointing to the exit. This will help to find your way in case you suddenly have doubt about it. It will also be a reference point from where the search started.
Once your exit is marked, you can try to cover your lights for a couple minutes, wait for your eyes to get used to the darkness and see if you can’t find number 3’s light somewhere. Photons (the elementary particle of light) travel fasts and travel far. You would be surprise to see how sensitive our eyes can be to very low light in pure darkness.
If still no trace of number 3, it is time to think, and think hard. Try to think about its whereabouts, where was the last time you saw it (should be right in the previous tie-off if your team awareness was good), did we recently pass a junction? was he taking pictures and may be a little bit behind? Try to think like you were number 3, and rule out possible and impossible scenario. When you’re ready to go, calculate the gas you may use for the search (refer to previous paragraph about recalculation) but don’t forget the golden rule: keep at least double of what you need to exit. Rule of third.
During this drill I try to emphasize the importance of not putting yourself in too much risk in order to find a missing buddy. We read too much report of people while looking for their buddy when this last is already out at the surface waiting. Remember that 1 fatality is still better than 2. Harsh but true.
The dive was focused on executing a clean and proper dive, recalculate at some point and execute a lost diver scenario. I placed a flashlight somewhere in the cave that was supposed to be number 3. Gave my students the signal “where is number 3” and the search started. The communication was pretty smooth and they calculated a safe search gas. They went back to where they were coming from and found the light a few meters away from the main line. Number one attached a spool to the main line to go pickup number 3 while number 2 stayed on the main line, controlling the situation, the recovery went well, number 3 was just having a nap. They then put number 3 between them and went smoothly towards the exit.
New day, new skills, new protocols. Cave Diving is all about creating a strong set of procedures that will highly raise your chance of survival in case a problem arises; There is no shortcut or short course, do not be lured into a cheap and express course, your life is at stake here!!
If you missed it you can read Day 9’s report here::https://www.sulawesidivetrek.com/index.php/2022/05/07/day-9-cave-diver-course/
List of all IANTD Courses, visit the IANTD Website : https://iantd.com/index.php/en-us/courses/iantd-ice-cave-mine-wreck-diving/