lamont
Contributor
as much as everyone slags off on 'learning to dive on the internet', this thread has been highly educational...
Stage planning in caves
- Thread starter rjack321
- Start date
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Karen Cleveland
Contributor
No, I don't always bring an extra scooter in Mexico. Depends on the cave. Burn time can be limited then swim. Any dive that you can't swim out of requires serious consideration of an additional scooter. Sometimes alternate exits (other cenotes) are known and can be used in an emergency to get out...but you best know where they lead and how to get back to civilization if they are used.
limeyx
Guest
So does that mean there's a "Karen's Hope" cenote somewhere ???? (just joking -- i seriously hope not)
OP
Are short bodies actually used in MX?? I have seen a bunch of standard tubes/batteries in ZG and then an old blue Mako (presumably used as a backup). I've never seen any short, 26Ah or Magnum packs or tubes down there so I just figured they weren't all that practical.
In terms of a stage dive in MX is a shortbody (60min burntime) functionally like a "1 stage scooter" with a standard being a "2+ stage scooter"? (obviously with appropriate backup).
In terms of a stage dive in MX is a shortbody (60min burntime) functionally like a "1 stage scooter" with a standard being a "2+ stage scooter"? (obviously with appropriate backup).
OP
Have you upsized your knife to a machete? :d
I have one down there collecting dust. And, GI3 only used Mako's down there. He had 4 or so. There really aren't many dives where you can even use a long body, but where you can the distances are huge. For just fun scooter dives a short body is really all you need. Given the depths and entrance logistics makos are actually more fun since they are so much lighter. For really easy dives we don't use backups on the short bodies. For slightly longer ones we carry an extra scooter and often burn both half of the entrance distance. Not practical to switch scooters regularly like this on deep dives, but in Mexico it makes sense and increases the odds of having a functioning scooter with plenty of burn if one develops problems.
OP
So how many stages would you be using for your typical short Gavin MX penetrations?Are you using 1/3rds on their burntime (~20 mins)?
This thread has been great, I think we need another on scooter usage
This thread has been great, I think we need another on scooter usage
OP
Ok this is more of a tech vs. cave observation...
When carrying a deco bottle with you in the ocean, we only reserve enough backgas to get to the last breathable source of gas (e.g. 70ft bottle). Yet in the cave we reserve enough backgas to get ALL the way out without (say just one or 2) backgas stages. Stages are assumed to be "lost". Its not on your person, so ok I understand the logic.
So here's the question part...
So let's say you drop both an O2, a 70ft bottle, and a backgas stage in a cave. Do you reserve enough backgas to deco/exit without all of them? Or reserve enough to cover one failure but not necessarily all three (like we would in the ocean).
When carrying a deco bottle with you in the ocean, we only reserve enough backgas to get to the last breathable source of gas (e.g. 70ft bottle). Yet in the cave we reserve enough backgas to get ALL the way out without (say just one or 2) backgas stages. Stages are assumed to be "lost". Its not on your person, so ok I understand the logic.
So here's the question part...
So let's say you drop both an O2, a 70ft bottle, and a backgas stage in a cave. Do you reserve enough backgas to deco/exit without all of them? Or reserve enough to cover one failure but not necessarily all three (like we would in the ocean).
First, I can't imagine a scenario where you would need a 70' bottle and would only have one stage in a cave. Second, given how little gas is actually used on deco relative to on the bottom, it really doesn't factor into the reserve. If both you and teammates are so low on gas that completeting deco if you lose an O2 bottle is an issue, you either just had the worst cave dive in history or your planning was bad.
Open water is different. Reserve gas planning is basically for an immediate ascent wherever the problem occurs. So, getting to useable gas is the primary concern. I don't know exactly what GUE teaches, but I generally plan to have enough gas for some amount of back gas deco (even if it is abreviated). Now, if the dive went sideways and you used reserve gas getting to the bottles useable depth this might not be the case since you can only plan for so many failures before it gets ridiculous.
Open water is different. Reserve gas planning is basically for an immediate ascent wherever the problem occurs. So, getting to useable gas is the primary concern. I don't know exactly what GUE teaches, but I generally plan to have enough gas for some amount of back gas deco (even if it is abreviated). Now, if the dive went sideways and you used reserve gas getting to the bottles useable depth this might not be the case since you can only plan for so many failures before it gets ridiculous.
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