Octo vs no octo

[ScubaSteve]

The air in your tank will expand as you surface, which may allow another breath or two from an 'empty' tank on the ascent; a good reason not to keep your reg in your mouth if there is no alternate available

Perhaps you can still edit your response where you clearly meant "....a good reason [-]not[/-] to keep your reg in ...." or at least I hope you did

 

[diver 85]

Heh, you noticed that too??


To the OP, you really should get an OW book (PADI or otherwise, they'll all have the same general info) and read it so you don't have to ask questions that have been thoroughly covered. I know that you're not planning on taking the class for a while, but it will be beneficial to have already read the information you need....and if there's something you don't understand or question why it's done a certain way, then by all means, ask....

Amen from the back corner of the room........

 

[Tortuga68]

Perhaps you can still edit your response where you clearly meant "....a good reason [-]not[/-] to keep your reg in ...." or at least I hope you did

Too late to edit thanks for picking it up

 

[ScubaSteve]

I knew what you meant.....figured I would offer the edit just in case others did not.

 

[4sak3n]

The air in your tank will expand as you surface, which may allow another breath or two from an 'empty' tank on the ascent; a good reason not to keep your reg in your mouth if there is no alternate available

You might also want to consider the bit I highlighted. The air in your tank will neither expand nor contract as you ascend (or descend). Saying that the air inside expands or contracts implies that the air is changing volume. In order to do this the vessel holding it has to change volume too and since your cylinder is rigid and inflexible (well, not completely, but any volume changes are so minute as to not factor into this) this is impossible.

Neither the volume of your cylinder or the volume or pressure of the air within changes when you change depth*.

I suspect what you meant though is that as you ascend the ambient pressure decreases which allows you to take another sip of air. e.g. when your tank is at 4 bar and the ambient pressure is at 4 bar you cannot use the air in your tank since there is no pressure differential. But when you ascend to where the ambient pressure is now 2 bar you can use 2 bar of the remaining 4 in your cylinder.

It results in the same thing (getting another breath or six of air as you ascend) but the reason is based on decreasing ambient pressure NOT changes in the volume of the air in your cylinder.

/nitpick

*although technically speaking the pressure might change as an indirect result of descending. As you descend the water tends towards getting colder and when the temperature of your cylinder decreases the pressure will decrease as well. But this, like the minute volume changes of your cylinder, will be so small as to not really be of concern.

 

[tom_n_tacoma]

Tell your friend I'm not diving with him and you ought to look for another buddy

 

[Bratface]

For my own safety and the safety of my buddy I dive with an octo. I have had to use it which was a big relief to the buddy.

 

[Tortuga68]

I suspect what you meant though is that as you ascend the ambient pressure decreases which allows you to take another sip of air. e.g. when your tank is at 4 bar and the ambient pressure is at 4 bar you cannot use the air in your tank since there is no pressure differential. But when you ascend to where the ambient pressure is now 2 bar you can use 2 bar of the remaining 4 in your cylinder

Yep, thanks

 

[Cerveza]

A fellow member told me not to get a octo. He said they were designed 40 years ago and the regulators today are just to unlikely to fail to carry one. He also said due to the improvements of the gear today the only real reason to loose air is human failure. SO he said there not worth carrying because of the add drag weight need to sink and that normaly there not taken care of and are usasly the first thing to get dragged through sand if the reg gets sand in it. he said he uses a pony bottle if he is diving deeper then 30 feet. but he sais for a new dive they should wait because a pony is unneed down to 30 feet.
do you use one

Your "fellow member" needs to go and do a refresher course, basicaly starting all over again, so the Octo adds drag, (hardly notice mine) what does a pony bottle do?
"The only reason to lose air is human failure", Contents guage failure?...what about an O-ring burst? imagine you and him on a dive and one of your rings goes at depth, could be you or could be your partner but one of you is in a situation where "Octo" help could be needed..

Sorry for sounding blunt but the guy needs a bit of a shake-up, not for his own sake but for his dive buddy.

 

[CNicoll]

I was first certified in 1974 and the difference in nearly every element of diving from then to now is huge. I re-certified in 2007, and it was worth going through the entire class again (and the Adv OW as well), and buying a completely new set of gear, including an octo.

In fact, that octo was used about 3 weeks ago when my older son had a valve fail on his tank at about 20'. He gave me the out of air signal, grabbed my octo and was breathing before I could even react. We were a calm as could be, and surfaced normally an in control. In 'my' day, we would have been buddy breathing off of one reg and it would have been a lot more stressful.

(BTW, our LDS has regular open pool sessions, which we take advantage of often and practice the OOA scenario frequently. Practice makes perfect!)