Secondary Air Question

[lifes an ocean]

About a 2 years ago, I know a little ways back, I had a situation on a dive where I couldn't find our ascent line, and instead of doing a free ascent I kept searching for the line. Well to make this story short, by the time I found the line and did my safety stop, I had pretty much burned my air almost out. My question lies in as a recreational diver, who will be doing dives to no deeper than about 70 feet, if that, would a secondary air, be a wise choice? If so what is a good size?

I saw a post earlier that had some cylinders that held some good amount of air, but seemed excessive to a degree for me.

As a side note, I have an idea of how much air I need left in my take before I make the ascent and safety stop so that I have a decent amount of air, but just asking, should Murphy turn up on another dive. Plus, being in the military, I just enjoy redundancy

Thanks in advance for the advice given.

 

[k ellis]

Check out the pony bottles they are small in size and very portable in some cases. If your not going deeper then 70 feet though you should be able to just share air with your buddy in the worst case scenarios. Look at Scuba.Com under pony bottles

 

[roakey]

Search the board for a term called "Rock Bottom". It's better to solve the root problem rather than add equipment to accomidate the root problem.

Roak

 

[lifes an ocean]

Okay, stupid question time. I type in "Rock Bottom" and get a million post, anyway you can help me narrow down what imparticular to look for when I type that in?

 

[spectrum]

This post may help you get a rational handle on what a good capacity is.

Pete

 

[nereas]

About a 2 years ago, I know a little ways back, I had a situation on a dive where I couldn't find our ascent line, and instead of doing a free ascent I kept searching for the line. Well to make this story short, by the time I found the line and did my safety stop, I had pretty much burned my air almost out. My question lies in as a recreational diver, who will be doing dives to no deeper than about 70 feet, if that, would a secondary air, be a wise choice? If so what is a good size?

I saw a post earlier that had some cylinders that held some good amount of air, but seemed excessive to a degree for me.

As a side note, I have an idea of how much air I need left in my take before I make the ascent and safety stop so that I have a decent amount of air, but just asking, should Murphy turn up on another dive. Plus, being in the military, I just enjoy redundancy

Thanks in advance for the advice given.

You are mixing apples with oranges. And these do not mix.

Pony bottles are a compact solution for either (1) diving solo or (2) diving with a buddy who has a tendancy to wander off. It thus represents a guaranteed alternate air source.

Ponies have nothing to do with needing extra gas. For that problem, you need a bigger tank.

At 70 ft your NDL time with nitrox is about 50 mins. With air it is about 45 mins. (I sum to 120 for nitrox and 115 for air to remember NDLs at various depths, as a shortcut to approximate.)

And as you become shallower, your NDL increases. So the isue is tank size appropriate to your RMV (breathing rate).

For times when you cannot find the anchor line during your ascent, you should drift or swim into the current at 15 ft, maintaining your 15 ft depth and performing your 3 min stop, and then ascend and look for the boat on the surface. You sould not overstay your dive time in excess of your normal turn-around time just because you are lost. This problem has nothing to do with tank size nor with pony bottles.

I have gotten into the situation many times where the computer or SPG says it is time to head back or up, and then I cannot locate the anchor line because it was not where I thought it should be. Guess what? You keep ascending anyway, swim into the current, and do your safety stop of 3 mins at 15 ft in the water column.

 

[SouthSideScubaSteve]

Spectrum,

First, thanks for the tip on how to calc air volume requited ... Second, sorry if this isn't the place for this qeustion, but being new to all this (diving and ScubaBoard), can you tell me how to "bookmark" that individual post for future reference?? :classic:

 

[The Kraken]

Needless to say, the question begs to be asked . . . where was your buddy?

the K

 

[spectrum]

Spectrum,

First, thanks for the tip on how to calc air volume requited ... Second, sorry if this isn't the place for this qeustion, but being new to all this (diving and ScubaBoard), can you tell me how to "bookmark" that individual post for future reference?? :classic:

Just save it as a book mark or favorite in your browser (IE or Firefox etc). I keep a folder of a few old posts that are helpful in just that way. Alternatively cut and paste the text in to Word or another text program and save it as a personal document. this way you are immune from a problem with an online database.

 

[Garrobo]

Work on your air consumption and you won't need a backup. Dive all dives as if you are diving alone.