Cavern In Doubles?

[jeandiver]

I've had to rescue just a few tanks from white water baths when a neck o-ring or burst disk has failed mid-fill. I've never seen an o-ring fail "just because", nor do I see any mechanism for it to.

Ditto.
When I was tank-monkey'ing up in Luraville , I had to rescue a few sets of doubles myself. Every time it was the valve burst disk.

I did Cavern in doubles (double 50's) and then switched to double 85's for my cave classes.

I do know some old-time cavers around here that DO dive doubles with NO isolator valve. They have dove this way for a long , long time and er , who's to argue with them.
Certainly not this chickie!

Jean

 

[MBH]

Oh this is good...my VERY FIRST trip to High Springs (I swear to God, Hand on the Bible) I Drove from N.GA. down I-75, to Alachua, FL, got off on 441, pulled into the- I think, the Comfort Inn. walked into the lobby, was getting my room, and all of a sudden I hear PAFOOSSSSSSSSSSTTTTTTTTTTTTTTTTTTTTTtsssstttttttttttttttttssssssssssss.

The lady behind the counter says something like "you gettin' a flat tar?"
I have 3 HP119's with 32% and 1 AL80 with air, all pumped up to 3600psi in the tank rack on the back of my truck.

I ran outside and found the extruded O-ring sticking out on one of my HP119's. It looked just about like the the one in the previous post. It was leaking bad enough to blow your hat off.

I went back into the lobby and told the desk clerk lady that it was just an air leak, and nothing to get worried about. (all the while I'm thinking it is some sort of omen But, I'm NOT superstitious...knock on wood, turn around three times and throw salt over my right shoulder.)

Just to let Y'all know....it took one hour and 45 minutes for my Worthington X-8 3442 119 to bleed down from 3600psi to zero from an extruded O-ring. And yes, the tank neck did ice over.

 

[jeandiver]

Oh this is good...my VERY FIRST trip to High Springs (I swear to God, Hand on the Bible) I Drove from N.GA. down I-75, to Alachua, FL, got off on 441, pulled into the- I think, the Comfort Inn. walked into the lobby, was getting my room, and all of a sudden I hear PAFOOSSSSSSSSSSTTTTTTTTTTTTTTTTTTTTTtsssstttttttttttttttttssssssssssss.

The lady behind the counter says something like "you gettin' a flat tar?"
I have 3 HP119's with 32% and 1 AL80 with air, all pumped up to 3600psi in the tank rack on the back of my truck.

I ran outside and found the extruded O-ring sticking out on one of my HP119's. It looked just about like the the one in the previous post. It was leaking bad enough to blow your hat off.

I went back into the lobby and told the desk clerk lady that it was just an air leak, and nothing to get worried about. (all the while I'm thinking is is some sort of omen But, I'm NOT superstitious...knock on wood, turn around three times and throw salt over my right shoulder.)

Just to let Y'all know....it took one hour and 45 minutes for my Worthington X-8 3442 119 to bleed down from 3600psi to zero from an extruded O-ring. And yes, the tank neck did ice over.

WOWZA !!!!
I hope it is NOT an omen and that your diving this weekend (etc) is very enjoyable.
Maybe we will see you around.
(Diving Ginnie Saturday morning)

Jean

 

[OneBrightGator]

MBH, do you think it extruded from exposure?

 

[MBH]

MBH, do you think it extruded from exposure?

I don't think so, but I really don't know. That particular tank had a VIP about 90 days prior and had been filled about seven or eight times prior to the O-ring extruding. Granted the tank had been riding in a rack on the back of my truck for 300 miles, it wasn't hot and nothing had hit the valve to work it loose.

 

[gkndivebum]

[...] I'll assume that most people who think o-rings don't blow have never filled their own tanks, or filled a lot of tanks. I'll assume that they've never had to shut down a valve with air spewing out their first stage (or tank neck)...thankfully I've never had to do that in a real scenario, but even doing it in a training situation can make things interesting pretty quickly.

A bit off-topic, but, yes, tank neck o-rings do fail, and fail under water. I keep this
one around to show my tech students why we dive doubles and carry bailout on
rebreathers.

This particular o-ring is from the diluent tank on my wife's rebreather. It let go while
at our 20 foot deco stop after an otherwise enjoyable 90 minute dive with a maximum
depth of 150 feet. Some excitement, but there's little need for diluent at that depth...
At the time it had perhaps 100 dives on it, and the tank was well within VIP.

Stuff happens.

 

[DivingCRNA]

For Cavern, they (PADI) do not allow doubles. I just took the PADI Cavern in May, and that was pointed out to me specifically by the instructor (who was also my Tec instructor, and with whom I usually dive doubles).

Doubles were not allowed for students when I did PADI Cavern. I believe the Instructor is REQUIRED to wear doubles, however.

PADI depth limits on the course rule out most of the necessity for doubles anyway.

 

[jimdiverman]

This has been a lively debate that I have missed for the last week. I just got the weekly update from Scubaboard, and it took a long time just to skim the posts. I am in the process of getting my full cave cert with PSAI. PSAI allows doubles at cavern and intro level. Their theory is that if you are going to dive in an overhead environment, starting out with doubles from the start is one less thing you need to learn when you are doing apprentice or still trying to figure out at full cave, since you'll be worrying more about finding your line or your buddy in a silt out, or keeping your sense of direction to know where the main line is. Starting on doubles earlier has given me that many more dives to begin to double natural instincts for handling the doubles. I had a whole new gear configuration anyway diving with the Classic redundant wing, HID light, reels, slate and my old Mares quattro fins instead of those split fins I had been diving with doing rec dives in the Caribbean.

I did my cavern with twin Faber 108s in Luraville, Branford and High Springs. For me two tanks is a lot of extra weight out of the water, but I also got to try some twin 130s. The 2 extra pounds per tank empty (plus the added fill weight) were more than I am comfortable with on land at this point, so I am probably going to stick with the 108s. Learning to dive with the twin sets was a good decision for me. I am glad that PSAI allows it for cavern.

I have been reading some other posts and have some comments relative to those. First off, the minimum air required to enter a cavern environment for PSAI is 80cf, not 72cf. I believe IANTD has the same minimum requirement. I am not disagreeing with the poster that 72cf may be the min for some certifying organizations, just stating that not all certifying organizations have the same minimum gas requirements.

Second, I believe that two tanks are better than one. Aside from doing S-drills and planning your dive conservatively, the cave (or cavern) diver wants above all else redundancy. What redundancy is there in a single tank? A single tank is a single point of failure, even if it is a 190. Even the simplicity of Hogarthian allows for doubles.

Maybe some agencies don't want to scare off prospective students with the added costs of HID lights, double tanks and valves and dry suits. I don't know, but the fact remains that our sport is expensive and we are/have/will be putting lots of dollars in to participate no matter which agency you choose for your training and subsequent diving.

Bottom line - I don't believe diving doubles in cavern is an unreasonable approach, particularly since the level of physical and mental effort only increases the deeper you penetrate into the cave system, and I haven't see any cave divers entering into a cave system with single tanks.

 

[TSandM]

Just wanted to amend my earlier posts about Ginnie Springs -- As a result of our visit there (really!), they will now allow TDI Intro divers to dive doubles. (It's really nice when the training director for an agency is in the truck next to yours, when the guard starts to get upset about it )

 

[SuPrBuGmAn]

Just wanted to amend my earlier posts about Ginnie Springs -- As a result of our visit there (really!), they will now allow TDI Intro divers to dive doubles. (It's really nice when the training director for an agency is in the truck next to yours, when the guard starts to get upset about it )

Sweet!

Oh, and about damned time