Question Do you cave dive exactly the way you teach people to cave dive? Do you cave dive the way you were taught?

[Manatee Diver]

Both of those lines begin at a "Safe Exit Point" so IAW training standards a line is not needed (Except at night).

I remember Harry, while telling me the history of Peacock, mentioned that discouraging running of lines at P1 outside of classes was part of the management plan.

 

[inquis]

Not an instructor and no firsthand observation of any doing so, but I strongly suspect visual jumps in conjunction with circuits would be one practice not strictly shared to, and especially when using a DPV. The risk varies, of course. Visually jumping back onto a Gold Line you verified (passed by the junction coming from the exit) earlier in the dive seems pretty innocuous. To me, that satisfies the underlying goal of, "maintain a continuous guideline to the exit." OTOH, multiple visual jumps in low traffic areas to lines not directly connected to the exit seems like a death wish. But then there are instances between such extremes.

I wonder how many divers visually jump between the Bone Line and the main line at Ginnie, especially at the far end not having personally verified the new line. Seems like most things, it comes down to a personal risk assessment.

 

[Taldan]

I remember Harry, while telling me the history of Peacock, mentioned that discouraging running of lines at P1 outside of classes was part of the management plan.

That makes a lot of sense then. Peacock 1 was my first cavern after getting my cert. I tied off, looked in the cave and saw I was a foot from the gold line. Felt a bit silly (still good practice though)

 

[rjack321]

The diver I've been diving with was taught (at stage cave level) to huddle & cuddle around the jump, wait for all 3 divers in the team to point in the exit direction and then pick up non-directional markers and cleanup the jump. That works nicely in big training caves with loads of space but I doubt that it would work in tighter passages, in halocline or with loads of gear and it could lead to confusion if the team looses orientation as nobody is actually facing the exit. And I'm fairly sure that the people who teach the protocol definitely don't use it in their real diving.

I was never taught such a thing and I am curious who is actually teaching the group huddle & point method described here. Sounds like something students would do if the instructor failed to teach them a better way.

Returning to a jump we:
1) confirm with everyone we're picking it up (#2 is key to front to back team communication here when single file)
2) pull your presence marker if any
3) #1 passes the jump, pulls their directional marker, and moves to the exit side
4) repeat for #2 if applicable
5) #3 pulls the jump and has both #1 and #2 on the exit side ready to continue.

Scales across all team and passage sizes.

 

[oya]

Great questions.

Instructors - what is one thing (skill, protocol and so on) that you teach, even though you would never use it in your own real cave diving?

Lost Line Drill.
I hate that drill. It takes up way too much time for something that, in reality, the lesson is, "DON'T LOSE THE LINE!!!!!!!!"
Dive in a way that your line awareness is never in question.

And what’s one thing that you do use but do not or cannot teach?

I recalculate gas needs a LOT and do very "branchy" cave dives. I can and do teach such a thing, but it is as advanced a skill as there is and definitely playing with fire.

 

[rjack321]

I recalculate gas needs a LOT and do very "branchy" cave dives. I can and do teach such a thing, but it is as advanced a skill as there is and definitely playing with fire.

Recalculating ain't that hard, if you start early. It is (or at least was historically) a small part of GUE Cave1.

Cave diving in general is playing with fire.

 

[steinbil]

Recalculating ain't that hard, if you start early. It is (or at least was historically) a small part of GUE Cave1.

Just finished C1 at the start of this month. It is part of the lost buddy protocol. We were expected to know (and remember - not write down anywhere) the gas pressure at various points during the dive, and to calculate needed gas to exit to determine how much gas you can use for searching for the buddy. So the awareness and ability to recalculate is trained.

However, we did not during the course recalculate gas during a dive to extend it by branching out, not sure if that is something still being taught. Our dives crossing a T, we did one complete dive on either side, recalculating at the surface.

 

[SpaceX Aquanaut]

Just finished C1 at the start of this month. It is part of the lost buddy protocol. We were expected to know (and remember - not write down anywhere) the gas pressure at various points during the dive, and to calculate needed gas to exit to determine how much gas you can use for searching for the buddy. So the awareness and ability to recalculate is trained.

However, we did not during the course recalculate gas during a dive to extend it by branching out, not sure if that is something still being taught. Our dives crossing a T, we did one complete dive on either side, recalculating at the surface.

This is what I learned in my OC Technical Wreck Penetration Class (nearly twenty years ago)--->

Modified Thirds Planning and Calculating On-the-Fly Gas Needed to Do a Lost Buddy Search in a Wreck Penetration:

Suppose you originally planned a wreck penetration starting with 200 bar at the entrance, with an openwater Rock Bottom minimum gas reserve of 50 bar. So 200 minus 50 bar equals 150 bar usable for the penetration --Modified Thirds of this value is 50 bar (one-third of 150 equals 50), so you would turn-around for egress when you consume 50 bar of gas with an actual SPG reading of 150 bar. If you needed to do a gas-sharing emergency egress with your buddy at this point, you would together need 100 bar to get out of the wreck, with 50 bar Rock Bottom remaining to get both of you to the surface (or your Oxygen deco bottle stop of 6m).

Lets say you used up 30 bar already getting to the entrance of the wreck for a total of 170 bar pressure available --can you quickly recalculate Modified-Thirds?

No problem with bar pressure metrics: 170 bar minus 50 bar Rock Bottom yields 120 bar usable for the penentration; One-Third of 120 bar is 40 bar which is your new Modified Thirds turn pressure value. Therefore you would turn the dive when you consume 40 bar for an actual turn pressure SPG reading of 130 bar (170 bar minus 40 bar equals the actual turn pressure SPG reading of 130 bar).

What if you lose your buddy at this instance, at the farthest distance inside the overhead your Modified Thirds value allows? How do you calculate the amount of gas to do a Lost Buddy Search?

Easy! At your turn around pressure reading of 130 bar on the SPG, simply add your Rock Bottom value to your Modified Thirds value (50 bar Rock Bottom plus 40 bar Modified Thirds equals 90 bar); Put a line-arrow pointing the way out on your mainline that you've laid, and take reference note of where you are inside the overhead at that exact point as well. Now go and search for your buddy with the understanding that you must be back at this line-arrow marker by the time your SPG reads this actual value (90 bar). So you would have from 130 bar down to 90 bar reading on your SPG, or 40 bar delta of gas to search for your buddy --if you were to do a straight line search down a long corridor inside the wreck for example, tactically you should use 20 bar out and 20 bar back to your line-arrow marker for a delta of 40 bar, and an actual end of search SPG reading of 90 bar-- you must start your egress whether you found your buddy or not when you use up this 40 bar delta of gas, at the line arrow marker, with the actual 90 bar final reading on your SPG.

At any point before your Modified Thirds turn pressure, for a lost buddy search, the final egress pressure is figured just by adding your Rock Bottom value to the amount of gas you've consumed on the penetration up to that point --for example you start with 170 bar on your SPG and you lose your buddy with 140 bar SPG reading for a delta consumption of 30 bar. 50 bar Rock Bottom plus delta consumption of 30 bar equals 80 bar. Drop a line arrow, and now you've got from 140 bar down to 80 bar (a tactical delta search pressure of 60 bar) to look for your buddy, and be back to your line arrow to egress smartly when your SPG reads 80 bar.

At any point after your Modified Thirds turn pressure, all you need to do to figure out a final egress pressure for a lost buddy search is to subtract your Modified Thirds value from your actual pressure reading, and place a line-arrow pointing out at this point on your mainline. For example, if you're egressing and you lose your buddy with 120 bar actual reading on your SPG: Subtract the Modified Thirds value of 40 bar from 120 bar -which equals 80 bar- and it is this actual reading that you must have on your SPG when you get back to your line arrow to successfully exit the wreck with all your Rock Bottom still available to reach the surface. Another way of looking at this, at your nominal turn-around point & afterward on egress, the amount of gas tactically available for a lost buddy search is always just your Modified Thirds value --in this case 40 bar.

Remember that on a lost buddy search, you will deliberately encroach and use up the Modified Thirds Reserve Value needed for an emergency gas-sharing egress contingency (and possibly use up Rock Bottom as well) --in other words, if you do find your lost buddy and worst of all worst scenarios he happens to be out-of-gas in a silt-out . . .well dea ex machina. I hope you're in a 3-person Team, somehow make it out and run into other divers on the outside who can donate gas & assist. .

[Note: the above gas plan is taken from wreck penetration dives on the HMCS Yukon (San Diego); USS New York (Subic Bay Philippines); HMAS Perth/USS Houston (Sunda Strait Indonesia); and various wrecks in Truk Lagoon. Depth 30m using twin 11L/bar tanks (double AL80's) and Oxygen deco.]
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[lermontov]

things I wasnt taught - I solo dive on occasion
things i dont do - a knotted secondary tie off (just a wrap or hitch)
thing I wont do - visual jumps

 

[lermontov]

No problem with bar pressure metrics: 170 bar minus 50 bar Rock Bottom yields 120 bar usable for the penentration; One-Third of 120 bar is 40 bar which is your new Modified Thirds turn pressure value. Therefore you would turn the dive when you consume 40 bar for an actual turn pressure SPG reading of 130 bar (170 bar minus 40 bar equals the actual turn pressure SPG reading of 130 bar).

I dont follow -if you started with 200 and you turn at 130 youve used 70 Bar to get where you are which means you need 140 to get you and your buddy back to surface? and thats bare minimum and with empty tanks