Cave diving on CC is safer than on OC?

[grantctobin]

Dive plan - 70 minutes 100 ft, 30 minutes overhead.
O/C setup - Back mount independent doubles, 2 side slung cylinders. All are HP117's with EAN32.
CCR setup - JJ-CCR with 2 slung HP117's with EAN32.
Subsurface planner:
Time to surface @planned 70 minutes is 60 minutes
O/C gas usage of 2/3 available.
CCR bailout gas usage at mid-dive is 2/3 of available.

Is the dive "safer" on O/C or CCR?

“30 minutes overhead” = 15 in and 15 out. Who needs 4xHP117 for a 15min of penetration at 30M? Who uses HP117 as stages?

This plan doesn’t make sense to begin with, why worry if it’s safer or not, especially if we don’t specify cave type?

 

[tomfcrist]

Who uses HP117 as stages?

Evidently people in Minnesota.

 

[O-ring]

Dive plan - 70 minutes 100 ft, 30 minutes overhead.
O/C setup - Back mount independent doubles, 2 side slung cylinders. All are HP117's with EAN32.
CCR setup - JJ-CCR with 2 slung HP117's with EAN32.
Subsurface planner:
Time to surface @planned 70 minutes is 60 minutes
O/C gas usage of 2/3 available.
CCR bailout gas usage at mid-dive is 2/3 of available.

Is the dive "safer" on O/C or CCR?

Trick question. Both dive plans are equally safe since I'll be sitting in my truck reading a paperback after pulling out the thumb and citing option number 1.

 

[gmerick]

"30 minutes overhead" - one direction. HP117's because minimum gas required can't be done on 4 80's in O/C.

Subsurface (5.0.10.0) dive plan created on 5/13/23
Runtime: 130min

	depth​	duration​	runtime​	gas​
➘	100ft	5min	5min	EAN32
➙	100ft	31min	36min
➙	100ft	34min	70min
➙	100ft	2min	72min
➚	40ft	2min	74min
-	40ft	4min	78min
➚	30ft	0min	78min
-	30ft	9min	87min
➚	20ft	0min	87min
-	20ft	16min	103min
➚	10ft	0min	103min
-	10ft	27min	130min
➚	0ft	0min	130min

CNS: 44%
OTU: 110
Deco model: Bühlmann ZHL-16C with GFLow = 30% and GFHigh = 75%
ATM pressure: 1,013mbar (0ft)
Gas consumption (based on SAC 0.71|0.60cuft/min):
97cuft/2,911psi of EAN32 (0cuft/0psi in planned ascent)
96cuft/2,929psi of EAN32 (0cuft/0psi in planned ascent)
62cuft/1,833psi of EAN32 (56cuft/1,779psi in planned ascent)
— Warning: not enough reserve for gas sharing on ascent!
0cuft/0psi of EAN32

 

[Manatee Diver]

"30 minutes overhead" - one direction. HP117's because minimum gas required can't be done on 4 80's in O/C.

Subsurface (5.0.10.0) dive plan created on 5/13/23
Runtime: 130min

	depth​	duration​	runtime​	gas​
➘	100ft	5min	5min	EAN32
➙	100ft	31min	36min
➙	100ft	34min	70min
➙	100ft	2min	72min
➚	40ft	2min	74min
-	40ft	4min	78min
➚	30ft	0min	78min
-	30ft	9min	87min
➚	20ft	0min	87min
-	20ft	16min	103min
➚	10ft	0min	103min
-	10ft	27min	130min
➚	0ft	0min	130min

CNS: 44%
OTU: 110
Deco model: Bühlmann ZHL-16C with GFLow = 30% and GFHigh = 75%
ATM pressure: 1,013mbar (0ft)
Gas consumption (based on SAC 0.71|0.60cuft/min):
97cuft/2,911psi of EAN32 (0cuft/0psi in planned ascent)
96cuft/2,929psi of EAN32 (0cuft/0psi in planned ascent)
62cuft/1,833psi of EAN32 (56cuft/1,779psi in planned ascent)
— Warning: not enough reserve for gas sharing on ascent!
0cuft/0psi of EAN32

That is a lot of gas for that dive. I plan for a SAC of 0.7cuft/min. For a 100ft cave dive for 30 minutes of penetration, like at Ginnie, Little River, or Twin that would be LP85s or LP108s and a single AL80 stage. Deco is around 10 minutes on oxygen. This is based on my actual profiles.

I don't think I have enough lift to carry four HP117s. That is what 40lbs of negative buoyancy?

 

[PfcAJ]

"30 minutes overhead" - one direction. HP117's because minimum gas required can't be done on 4 80's in O/C.

Subsurface (5.0.10.0) dive plan created on 5/13/23
Runtime: 130min

	depth​	duration​	runtime​	gas​
➘	100ft	5min	5min	EAN32
➙	100ft	31min	36min
➙	100ft	34min	70min
➙	100ft	2min	72min
➚	40ft	2min	74min
-	40ft	4min	78min
➚	30ft	0min	78min
-	30ft	9min	87min
➚	20ft	0min	87min
-	20ft	16min	103min
➚	10ft	0min	103min
-	10ft	27min	130min
➚	0ft	0min	130min

CNS: 44%
OTU: 110
Deco model: Bühlmann ZHL-16C with GFLow = 30% and GFHigh = 75%
ATM pressure: 1,013mbar (0ft)
Gas consumption (based on SAC 0.71|0.60cuft/min):
97cuft/2,911psi of EAN32 (0cuft/0psi in planned ascent)
96cuft/2,929psi of EAN32 (0cuft/0psi in planned ascent)
62cuft/1,833psi of EAN32 (56cuft/1,779psi in planned ascent)
— Warning: not enough reserve for gas sharing on ascent!
0cuft/0psi of EAN32

Unrealistic descent time, deep stops profile, no deco gas.

Hard pass.

 

[billgraham]

I saw no reason for going to FL over MX before (besides getting experience in high flow caves) but now with all the great advertisement you guys do, I don't want to go at all

It's just good-natured goofing around. Florida is the place to be, don't let anyone fool you!

 

[rddvet]

It's just good-natured goofing around. Florida is the place to be, don't let anyone fool you!

SHHHH. We've got enough people coming down to florida to dive. We aren't going to complain if they want to go to mexico

 

[Celt]

"30 minutes overhead" - one direction. HP117's because minimum gas required can't be done on 4 80's in O/C.

Subsurface (5.0.10.0) dive plan created on 5/13/23
Runtime: 130min

	depth​	duration​	runtime​	gas​
➘	100ft	5min	5min	EAN32
➙	100ft	31min	36min
➙	100ft	34min	70min
➙	100ft	2min	72min
➚	40ft	2min	74min
-	40ft	4min	78min
➚	30ft	0min	78min
-	30ft	9min	87min
➚	20ft	0min	87min
-	20ft	16min	103min
➚	10ft	0min	103min
-	10ft	27min	130min
➚	0ft	0min	130min

CNS: 44%
OTU: 110
Deco model: Bühlmann ZHL-16C with GFLow = 30% and GFHigh = 75%
ATM pressure: 1,013mbar (0ft)
Gas consumption (based on SAC 0.71|0.60cuft/min):
97cuft/2,911psi of EAN32 (0cuft/0psi in planned ascent)
96cuft/2,929psi of EAN32 (0cuft/0psi in planned ascent)
62cuft/1,833psi of EAN32 (56cuft/1,779psi in planned ascent)
— Warning: not enough reserve for gas sharing on ascent!
0cuft/0psi of EAN32

With that plan I’m starting to understand why some might need a rebreather, I could make the dive on OC with a pair of 15ltrs of EAN36 @ 250bar and a 7ltr of EAN50 in 81min.
30M / 70min EAN36 (5500 ltrs)
20m / 1min EAN50
10m / 1min EAN50
3m / 9 min EAN50

 

[ofg-1]

It's just good-natured goofing around. Florida is the place to be, don't let anyone fool you!

This is how they suck you in, don't listen to Bill.

Florida is just as bad you have always heard. Think of all the mosquitoes, ticks, spiders, sand fleas and no seeums that will miss out on having you around. Who will the alligator, snakes, big snapping turtles, snails, invasive pythons have to stare at? And brain eating amoeba, your brain is as good as anyones. And in winter, who will all the semi frozen giant lizards fall out of the trees on?

And THIS is a typical local businessman.

I'm 5th generation Floridian, believe me.