Dumb Things I've Done

[gcarter]

Humm..it is about both volume and pressure. Both are taken into consideration but pressure drives the gear and not volume! If I take a single 120 tank down to 400 psi then using the conversion factor then I have about 18 cuft of gas. Now would you really like to be at 85' facing a deco obligation with 18 cuft of gas available? Not me. I usually dive thirds. A very simple answer I hope you understand.

Thanks for the reply. The statement about thirds indicates that the "SHOULD HAVE LEFT IT THAT WAY!" was in jest? (Not opening the valve could easily have led to an OOA since the volume was lower than believed before the equalization).

(For reference, I am not looking for simple per se, I am looking for clear. This is not a criticism - it can be difficult to achieve with varied levels of previous knowledge)

 

[Scuba Lawrence]

Thanks for the clarification, Tony. As I understand it, the issue was 400psl at 85 feet, not that something about the tanks equalizing being a problem. I couldn't figure out why equalizing would put an end to a dive, but realizing the real gas situation was definately a good reason to head for daylight.

 

[TONY CHANEY]

Thanks for the reply. The statement about thirds indicates that the "SHOULD HAVE LEFT IT THAT WAY!" was in jest? (Not opening the valve could easily have led to an OOA since the volume was lower than believed before the equalization).

(For reference, I am not looking for simple per se, I am looking for clear. This is not a criticism - it can be difficult to achieve with varied levels of previous knowledge)

OK a more simple or "clear" way of looking at the situation. You have a 120 tank at 85' reading 1000 psi. A buddy comes over to you and shows that he / she has low gas available. You hook us a transfer whip and top his/her tank off. You watch your psi drop from 1000 psi down to 400-500 psi which decreases you available gas. Now do you continue to dive knowing that you do not have enought gas to drive your regs or enought gas should a bad event arise or do you abort he dive? Have you ever wondered why a boat Capt. asked you to be back on the boat no less than 500 psi? There is a reason. Look it up.

 

[gcarter]

OK a more simple or "clear" way of looking at the situation. You have a 120 tank at 85' reading 1000 psi. A buddy comes over to you and shows that he / she has low gas available. You hook us a transfer whip and top his/her tank off. You watch your psi drop from 1000 psi down to 400-500 psi which decreases you available gas. Now do you continue to dive knowing that you do not have enought gas to drive your regs or enought gas should a bad event arise or do you abort he dive? Have you ever wondered why a boat Capt. asked you to be back on the boat no less than 500 psi? There is a reason. Look it up.

I sense some animosity here and I am not sure why. You equalized your tanks and experienced a pressure drop from 1000 psi to 400 psi and aborted the dive.

I am not criticizing the fact that you aborted the dive. But your explanations are ambiguous. You made the statement "I SHOULD HAVE LEFT IT THAT WAY!" in reference to your isolator valve. I asked if this was made in jest or not, which has not been answered. If it was made in jest, your reason for aborting the dive is much more clear than if it was a serious statement. Was it knowledge of the actual total volume? Was it the volume per cylinder? Was it something specific to pressure requirements of your regulators? Was it some other reason? Asking me questions about what I would do does not explain YOUR rationale.

In my opinion, I would have aborted simply because I had discovered I had less gas volume than previously thought and would consider it insufficient to continue. Simple, clear statement.

(FWIW, those same boat Captains will tell you that less than 500 psi will result in water in your (their) rental tank - which is false. At 85' - <4ATM, the water pressure is nowhere near 500 psi and ANY positive pressure in the tank relative to the external environment keeps the water out. If I have positive pressure at the end of a dive, whether it be 50 psi or 500 psi I have no issue).

I am most emphatically NOT looking for an argument. I will not ask for further clarification.

 

[mmadiver]

So my SPG showed something like 1000 psi (please forgive the math in that I can't remember the exact numbers) which is a lot of gas considering I had double 120's. When I discovered the problem and turned on the isolater I watched, it horror I might add, as my SPG dropped to less than 400 psi or somewhere there about. No a good feeling considering that you are on your second dive, approaching deco, 85' down and without the needed driving pressure for the Poseidon regs. No worries. Signal buddies that I am going up and end the dive OK to dive another day.
I hope that this helps.

Interesting that it would drop to 400psi from 1000psi. In order for that to happen you would of had negative pressure (i.e. -200psi) in your right tank.


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[TravisD]

Interesting that it would drop to 400psi from 1000psi. In order for that to happen you would of had negative pressure (i.e. -200psi) in your right tank.

Gauges are the least accurate at the ends of their ranges, so being a couple hundred pounds off at the bottom of the scale may not be that far out of the question?

 

[mmadiver]

Gauges are the least accurate at the ends of their ranges, so being a couple hundred pounds off at the bottom of the scale may not be that far out of the question?

His reasoning behind aborting the dive is that 400psi was approaching the "driving pressure" of his regulator. Prior to equalization, assuming his right tank was empty since it equalized from 1000 to 400psi, his primary regulator would of been well below the driving pressure...


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[TONY CHANEY]

I sense some animosity here and I am not sure why. You equalized your tanks and experienced a pressure drop from 1000 psi to 400 psi and aborted the dive.

I am not criticizing the fact that you aborted the dive. But your explanations are ambiguous. You made the statement "I SHOULD HAVE LEFT IT THAT WAY!" in reference to your isolator valve. I asked if this was made in jest or not, which has not been answered. If it was made in jest, your reason for aborting the dive is much more clear than if it was a serious statement. Was it knowledge of the actual total volume? Was it the volume per cylinder? Was it something specific to pressure requirements of your regulators? Was it some other reason? Asking me questions about what I would do does not explain YOUR rationale.

In my opinion, I would have aborted simply because I had discovered I had less gas volume than previously thought and would consider it insufficient to continue. Simple, clear statement.

Sorry to come off in a manner that would make you feel that way. That was not my intent.

Interesting that it would drop to 400psi from 1000psi. In order for that to happen you would of had negative pressure (i.e. -200psi) in your right tank.

I was not sure of the content of the right tank in that I do not have a pressure guage on that first stage. Notice that I said that the reg was getting rather hard to breathe from. What I failed to state is that I switched regs several times as well as checking the surface / dive switch. As always, when someting does not feel right with the reg I am breathing from I go to the backup reg. So I was thinking that there was something wrong with the reg because I had over 1000 psi and the backup reg was working prefectly. So surface / dive switch moved back and forth, tried reg again and it did not change anything. Back to backup reg. Check left and right tank's valves and both are fully open (I never do the 1/4 turn thing). Still no help. It was at this point that I check the isolater. Anyone who has ever had more gas in one tank than the other will tell that you really can hear the gas transfering from one tank to the other on either doubled up or using a fill wip. Well the sound that I was hearing let me know 1) exactly what I had just done and 2) the situation I just created. The tanks were double 120's. I started thinking that I had over 1000 psi spread over two 120's and not just one. Even if I had a single 120 with 1000 psi I would have chnged the dive plan to include not diving at all. But again I did not know. Poseidon Odin Jetstreams love pressure but do not do so well with low pressure. I hope that this link helps: http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/4105/ADA313945.pdf?sequence=1 When the gas was equalized I now did not have the rather large driving pressure for the regs. So it is at this point where I compounded the situation. I could have done the dive on the backup reg. with a single tank with 1000 psi but not with only 400 psi. So now both regs are breathing different than at a good working pressure. So I chose to go up where if I have additional complications I could jump on my 45 cuft tank with oxygen and complete any deco / safety stops. I hope that this helps clear up the silt that I have created.

His reasoning behind aborting the dive is that 400psi was approaching the "driving pressure" of his regulator. Prior to equalization, assuming his right tank was empty since it equalized from 1000 to 400psi, his primary regulator would of been well below the driving pressure...Sent from my iPad using Tapatalk

Exactly and better stated!

 

[Finneli Felwitch]

Bit of background on qualifications: certified in 1998, am now a Master Diver with SSI, 200 logged ocean dives, own a ton of scuba gear. Currently working on a NAUI Dive Master certification.

What stupid things have I done?

-Heading to some Florida Springs with family, 3 hour drive, got to Springs, forgot Regulators on Kitchen Table.
-Took a plane from Florida to Grand Cayman Islands with family, forgot spare hoses, save a dive kit---LP hose burst, payed $60 for a 20 inch. rubber hose.
-Took a boat trip, got to dive site, left dive computer on seat of car.
-Took a boat trip, got to dive site, left weights at home.
-Went night diving with family, forgot to put new batteries in flashlights, had them all die mid-dive.
-Did not buy glow sticks at home (pack of 6 for $2), instead payed $3 per stick at dive destination.
-Spent a total of $50 in glow sticks over the years, could have bought those cheap battery powered glow sticks for a lot less.


While working on Dive Master certification:

-Forgot to get weights for a student before having her go into the water.
-Forgot to turn on the students air before she got into the water (How they hell did I forget to turn on the air!?)
-Practicing scuba skills at springs in 15 ft. Group surfaces, I surface, leaving a diver at 15 ft.

I seriously have to get my act together if I am going to be a Dive Master.

 

[diver 85]

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