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danielh03
12-14-2007, 22:41
We have all used Octo's, or Intergrated Inflaters, or at least seen one. But how many divers out there have considered a Redundant Breathing System? Yes, you are looking at buying a 20-30 cf tank, and a first stage, but does the cost out weigh the advantages? Condider you are in an out of air situiation. If you have a buddy close at hand, your in great shape considering. But what if your buddy was a considerable distance from you? Or a free flow in your first stage on your primary breathing system? When I went through ANDI (American Nitrox Divers International) I learned that on octo is good, but also learned about using a RBS as well. Whats your thoughts on them?

BSea
12-14-2007, 23:04
I've got a 19 that I take along sometimes. It just depends on the dive. I'll bet there are a good number of divers out there that use ponies (RBS) from time to time.

texdiveguy
12-14-2007, 23:18
I use a 19cf slung RGS on every single cylinder dive I make regardless...really a no brainer IMO!

MSilvia
12-14-2007, 23:24
Yes, you are looking at buying a 20-30 cf tank, and a first stage, but does the cost out weigh the advantages?
You're looking at a second stage, hose, and pressure gauge too, and don't forget you'll want a way to mount it.

Personally, I have double HP100s connected with an isolator manifold and a separate Apeks DS4/TX50 regulator on each post, and I've been on dives where I used that as well as two AL40 deco cylinders, each with an independent first and second stage regulator and SPG. I have yet another AL19, two LP72s, and a full Genesis reg set that I wasn't using at the time.

Yeah, I think getting a redundant gas supply is worth it. :)

SkuaSeptember
12-15-2007, 06:57
I practise CESAs in the pool with my students on a regular basis and know I can do a full pool length no problem. This doesn't allow for a safety stop however. So, for any dive planned to more than 60ft. I bring a pony bottle. It happens to be an Al30 which might be overkill, but I got it for free so WTH.

wheelman
12-15-2007, 07:54
I don't think you can go wrong with redundancy! For me it is worth the cost even if I never use it in an emergency.

Grin
12-15-2007, 09:08
I religiously dive a 13 pony. I removed my backup 2nd stage from my octo, and I don't have a octo inflator.
If your diving to less than 100 ft a 13 is perfect. Over 100 ft a 19 is the ticket. I don't see the need for a 30. Even stressed out a 19 is plenty for a perfect safe accent. Since a 19 is the same diameter as a 13 and just a little longer the 19 is a good choice.
You have no clue it's on your back, in or out of the water, so why not eliminate situations virtually 100%.

Flatliner
12-15-2007, 09:42
I want one, just haven't got one yet.

mm2002
12-15-2007, 09:55
After reading umpteen threads on this forum I think I've decided to get a 13. I have a spare air, but now that I've read a lot of the logistics of it, I'm not to crazy about depending on it in a real emergency.

BSea
12-15-2007, 11:20
After reading umpteen threads on this forum I think I've decided to get a 13. I have a spare air, but now that I've read a lot of the logistics of it, I'm not to crazy about depending on it in a real emergency.I did basically the same thing. Except I got a 19. Originally I mounted it on the tank straps using the zeagle pony bottle attachment (http://scubatoys.com/store/detail.asp?PRODUCT_ID=ZeaglePonyBottleAttachment), and it works well. But now I just sling it. It's less hassle that way IMHO.

FroggDVR
12-15-2007, 11:32
Yes, you are looking at buying a 20-30 cf tank, and a first stage, but does the cost out weigh the advantages?
You're looking at a second stage, hose, and pressure gauge too, and don't forget you'll want a way to mount it.

Personally, I have double HP100s connected with an isolator manifold and a separate Apeks DS4/TX50 regulator on each post, and I've been on dives where I used that as well as two AL40 deco cylinders, each with an independent first and second stage regulator and SPG. I have yet another AL19, two LP72s, and a full Genesis reg set that I wasn't using at the time.

Yeah, I think getting a redundant gas supply is worth it. :)


Iwould agree with this :) :)
I dive double 80's or 120's with 1 or 2 40cf deco bottles. So yes to slinging a 30 even when diving a single 80.

Or how about this. Whats your life worth to you, your family/ friends.

somewhereinla
12-15-2007, 11:53
I religiously dive a 13 pony. I removed my backup 2nd stage from my octo, and I don't have a octo inflator.
If your diving to less than 100 ft a 13 is perfect. Over 100 ft a 19 is the ticket. I don't see the need for a 30. Even stressed out a 19 is plenty for a perfect safe accent. Since a 19 is the same diameter as a 13 and just a little longer the 19 is a good choice.
You have no clue it's on your back, in or out of the water, so why not eliminate situations virtually 100%.

13 is way more than enough from over 100ft. Would love to know how you got to that conclusion. Actually, an experience diver can ascend from 100ft with only one (full) breath of air (Boyle's law). With 6cf of air, one should be able to ascend from the recreational limit to the surface and be able to do a 3mn safety stop.

terrillja
12-15-2007, 13:37
We have all used Octo's, or Intergrated Inflaters, or at least seen one. But how many divers out there have considered a Redundant Breathing System? Yes, you are looking at buying a 20-30 cf tank, and a first stage, but does the cost out weigh the advantages? Condider you are in an out of air situiation. If you have a buddy close at hand, your in great shape considering. But what if your buddy was a considerable distance from you? Or a free flow in your first stage on your primary breathing system? When I went through ANDI (American Nitrox Divers International) I learned that on octo is good, but also learned about using a RBS as well. Whats your thoughts on them?

I have a 30CF pony, which I have on every dive. I have the added issue in NH of cold water, where a freeze-up is quite possible depending on the season. IMO the cost is well worth it, the thing is that you want to keep in mind that you want a quality setup, not whatever you can get together for as little as possible. When you need it it work, you NEED it to work, 100%.

in_cavediver
12-15-2007, 15:45
I religiously dive a 13 pony. I removed my backup 2nd stage from my octo, and I don't have a octo inflator.
If your diving to less than 100 ft a 13 is perfect. Over 100 ft a 19 is the ticket. I don't see the need for a 30. Even stressed out a 19 is plenty for a perfect safe accent. Since a 19 is the same diameter as a 13 and just a little longer the 19 is a good choice.
You have no clue it's on your back, in or out of the water, so why not eliminate situations virtually 100%.

13 is way more than enough from over 100ft. Would love to know how you got to that conclusion. Actually, an experience diver can ascend from 100ft with only one (full) breath of air (Boyle's law). With 6cf of air, one should be able to ascend from the recreational limit to the surface and be able to do a 3mn safety stop.

I'd believe you if it was a relaxed expierenced diver. Here's the realities that change you assessment.

1) If you expect air, get water, you WILL increase anxiety which increases air consumption. Most figure to double normal SAC for planning purposes

2) You may have a tank with 6cft, but you won't have the full amount accessible. It takes 100-200psi for the reg to operate. (130psi average Intermediate pressure + ambient)

3) You assume zero bottom time to sort out a problem and ascend. Personally, I plan for 1-2 minutes there.

Assume 0.5 SAC. At 100ft, its 4ata or a consumption rate of 2cft/min. Double it for emergency anxiety means 4cft/min at 100ft. That means you have 1 - 1.5 minutes at depth till OOA again. Even ideal case is 2-3 minutes at depth.

At 15ft, 1.5 ata, you use 0.75cft/min or have 8 minutes for the full 6cft.

When you start with the math and how much gas it takes, 6cft is not a great safety margin. Going to 13, doubles the numbers above.

danielh03
12-15-2007, 20:36
So most of us agree its great to have! I was looking at getting a 19 cf set up with a quick draw bracket in case i have to give it to my buddy. I like knowing that I can give them air, and the tank, and stay far enough away from them that in their panic, I wont get put into a bad spot! Would you keep your octo on your primary 1st stage, or would you just put it on your pony so that you are 1 hose and reg lighter?

mm2002
12-15-2007, 21:27
My plans are to keep my existing 2nd stage and octo, and use the pony for a complete redundant system.

PsychDiver
12-18-2007, 06:58
I have been looking at adding a redundant air supply. I guess I better get off the fence and get an order in. I think, for the type of diving I do (less than 100') I will get a 13cf. Thanks for the discussion and the reminder increase my safety margin.

danielh03
12-18-2007, 12:36
I have been looking at adding a redundant air supply. I guess I better get off the fence and get an order in. I think, for the type of diving I do (less than 100') I will get a 13cf. Thanks for the discussion and the reminder increase my safety margin.

Do you plan on doing deeper dives in the future? how much more is a 19cf?

MSilvia
12-18-2007, 12:52
how much more is a 19cf?
If you buy from ScubaToys, a 19 costs a whopping $12 more than a 13, and that's before any discounts. Since I don't feel like two 40s are in the way when I have them slung at the same time, I have some difficulty imagining why someone would opt for a 13 instead of a 19 or more.

MSilvia
12-18-2007, 13:40
13 is way more than enough from over 100ft. Would love to know how you got to that conclusion.
I got to the same conclusion... a 13 isn't adequate for ensuring a safe and prudent self-rescue from 100+ feet. Let's imagine a scenario where two experienced divers are paired up on a 120' wreck dive with a moderate surface current and 20-30' visibility, and the boat has tied up to a permanent mooring on the bow of the 140' long wreck. That's not an unusual scenario here. For the sake of argument, let's also assume it's an overcast day with 2' seas and 1 mile surface visibility.

While the pair is checking out the large exposed screws at the stern end of the wreck, diver #1 (who has mediocre buddy skills) notices a large lobster, so he whips out his catch bag and goes after it, stirring up some silt in the process. Diver #2 doesn't see where diver #1 went, but as visibility begins to deteriorate, he notices his reg is breathing really hard, and a quick SPG check reveals that for whatever reason he's down to 180 psi with no buddy in sight. He switches to his trusty AL13 pony, glad that he had the forethought to bring it, but upset at himself for not keeping better track of his available gas supply and buddy.

He now has a couple of big choices to make.

Should he spend several minutes looking for his buddy to tell him he's aborting the dive, or just go now and leave diver #1 to figure it out for himself and ascend alone? What if diver #1 was in trouble too?
Should he ascend directly to the surface and risk things like not being spotted by the boat, being swept off in a current that may have gotten stronger at the surface while making a safety stop, etc., or should he spend several minutes swimming back to the bow of the wreck in order to ascend the mooring line?Assuming he wants to take the time to find diver #1, and that he wants to ascend the mooring line and make a safety stop, he might be breathing off that pony for... oh, lets say 5 minutes before he even begins his ascent. Assuming he's cool as a cucumber about all of this might be pushing it, but he's an experienced diver, so let's assume he's keeping panic in check and has a SAC rate right now of .75.

Right now, he's under 4.7 ATA of pressure, so he's sucking down 3.6 cubic feet of gas per minute at the bottom. In 5 minutes, he uses 18 cubic feet of gas, and now he's in a position to safely ascend with his buddy, which is good, because his AL13 ran out of gas several minutes ago, and he needs to share. Assuming he had a bigger pony though, let's finish the calculations and see how much gas he'd use making a normal 30ft/minute ascent with a 3 minute stop at 20 feet. We'll round up, and use the deepest depth for each given minute for our calculations, in order to make sure we aren't short-changing our poor hypothetical diver.

For his ascent from 120 to 90fsw, we'll credit him for another minute at 120, which we already decided was 3.6 cubic feet consumed. 90 feet is 3.8 ATA, so he'll use 2.9 cubic feet during the ascent to 60fsw. From 60 to 30, he'll use another 2.2 cubic feet... plus another .5 cubic feet during his 20 second ascent to the safety stop. At 20 feet for 3 minutes, he'll use 3.9 cubic feet, and in the 40 seconds it takes him to surface under control from there, he'll use another .9 cubic feet or so.

The way I figure it, 18+3.6+2.9+2.2+0.5+3.9+0.9=32. Now, I'll grant that I'm being conservative with my estimates, and that a diver who decides to abandon all hope, buddies, safety considerations, and protocol and bolt to the surface could make a CESA from 100+ feet using just a few cubic feet of gas. It makes me wonder though... if the difference between planning for a "jackass bailout" and a controlled safe ascent with your buddy is $20 worth of additional capacity in your pony, why the hell would you decide an AL13 is the right tank for the dive? It's not like a CESA is your best option here, and a much better one isn't substantially more expensive. Having done the math before trying to figure out his gas requirements the hard way, diver #2 might be sitting on the boat with his buddy and 8 or 9 cubic feet of gas left in his AL40 pony, instead of bobbing around the mid-Atlantic by himself at night, hoping the coast guard will find him and his two empty tanks before he makes it to Greenland.

By my calculation, an AL30 might or might not be big enough to ascend under control in an emergency from the deep end of recreational limits. Would an AL13 pony be better than nothing? You bet your butt it would. Would an AL13 be better than competitively priced alternatives? I don't believe so, but I'm open to arguments to the contrary.

Personally, the only things my AL19 gets used for is pressurizing my regs while I rinse them in the bathtub, or fishing my frisbees out of water hazards after I play disc golf.

MSilvia
12-18-2007, 16:50
Does the way I reached that conclusion make sense, or is it just making your eyes glaze over?

Iceman
12-18-2007, 17:32
MSilva: Your calculations make sense with one caveat, primarily for those who read your post. That is that all, I mean ALL, SAC rate and gas consumption calculations are assumptions. Assumptions are necessary to do some kind of analysis. But, a wise diver never plans on having "just enough gas" to do the job.

That is why I almost always dive some kind of twin cylinder configuration. It may be manifolded doubles, or it may be independent doubles, or it may be a back mounted single with a slung tank. But, I always have way, way more gas on board than what I expect to need.

To me, the wise diver does something like what the airlines do. They plan for enough fuel to get to their destination and hang around for awhile, go to their alternate and hang around for awhile and then add in some more.

Or, another way: If you can't afford to buy big tanks, or aren't strong enough to handle them, you aren't wealthy enough, or strong enough to dive; period.

CompuDude
12-18-2007, 17:46
Does the way I reached that conclusion make sense, or is it just making your eyes glaze over?

Well put, Matt. The one wrinkle your scenario could benefit from is one where BOTH divers get too excited and manage to go OOA. Suddenly the "roomy" 19cf bottle is feeding two, and probably is not going to give enough gas. Hopefully both divers have 19cf with them, and both maintain their gear well and made sure it was fully charged and ready, and neither have any problems with them...

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
12-18-2007, 17:53
It makes a lot of sense to me. I bought a 40cf pony because I thought a 40 gave me a better chance of coming up on the wreck. Only question I have is whether the reg is good enough. My primary is an Apeks XTX 100 and my pony is a Mares MR12 first with proton second.

WaScubaDude
12-18-2007, 19:14
13 is way more than enough from over 100ft. Would love to know how you got to that conclusion.
I got to the same conclusion... a 13 isn't adequate for ensuring a safe and prudent self-rescue from 100+ feet. Let's imagine a scenario where two experienced divers are paired up on a 120' wreck dive with a moderate surface current and 20-30' visibility, and the boat has tied up to a permanent mooring on the bow of the 140' long wreck. That's not an unusual scenario here. For the sake of argument, let's also assume it's an overcast day with 2' seas and 1 mile surface visibility.

While the pair is checking out the large exposed screws at the stern end of the wreck, diver #1 (who has mediocre buddy skills) notices a large lobster, so he whips out his catch bag and goes after it, stirring up some silt in the process. Diver #2 doesn't see where diver #1 went, but as visibility begins to deteriorate, he notices his reg is breathing really hard, and a quick SPG check reveals that for whatever reason he's down to 180 psi with no buddy in sight. He switches to his trusty AL13 pony, glad that he had the forethought to bring it, but upset at himself for not keeping better track of his available gas supply and buddy.

He now has a couple of big choices to make.

Should he spend several minutes looking for his buddy to tell him he's aborting the dive, or just go now and leave diver #1 to figure it out for himself and ascend alone? What if diver #1 was in trouble too?
Should he ascend directly to the surface and risk things like not being spotted by the boat, being swept off in a current that may have gotten stronger at the surface while making a safety stop, etc., or should he spend several minutes swimming back to the bow of the wreck in order to ascend the mooring line?Assuming he wants to take the time to find diver #1, and that he wants to ascend the mooring line and make a safety stop, he might be breathing off that pony for... oh, lets say 5 minutes before he even begins his ascent. Assuming he's cool as a cucumber about all of this might be pushing it, but he's an experienced diver, so let's assume he's keeping panic in check and has a SAC rate right now of .75.

Right now, he's under 4.7 ATA of pressure, so he's sucking down 3.6 cubic feet of gas per minute at the bottom. In 5 minutes, he uses 18 cubic feet of gas, and now he's in a position to safely ascend with his buddy, which is good, because his AL13 ran out of gas several minutes ago, and he needs to share. Assuming he had a bigger pony though, let's finish the calculations and see how much gas he'd use making a normal 30ft/minute ascent with a 3 minute stop at 20 feet. We'll round up, and use the deepest depth for each given minute for our calculations, in order to make sure we aren't short-changing our poor hypothetical diver.

For his ascent from 120 to 90fsw, we'll credit him for another minute at 120, which we already decided was 3.6 cubic feet consumed. 90 feet is 3.8 ATA, so he'll use 2.9 cubic feet during the ascent to 60fsw. From 60 to 30, he'll use another 2.2 cubic feet... plus another .5 cubic feet during his 20 second ascent to the safety stop. At 20 feet for 3 minutes, he'll use 3.9 cubic feet, and in the 40 seconds it takes him to surface under control from there, he'll use another .9 cubic feet or so.

The way I figure it, 18+3.6+2.9+2.2+0.5+3.9+0.9=32. Now, I'll grant that I'm being conservative with my estimates, and that a diver who decides to abandon all hope, buddies, safety considerations, and protocol and bolt to the surface could make a CESA from 100+ feet using just a few cubic feet of gas. It makes me wonder though... if the difference between planning for a "jackass bailout" and a controlled safe ascent with your buddy is $20 worth of additional capacity in your pony, why the hell would you decide an AL13 is the right tank for the dive? It's not like a CESA is your best option here, and a much better one isn't substantially more expensive. Having done the math before trying to figure out his gas requirements the hard way, diver #2 might be sitting on the boat with his buddy and 8 or 9 cubic feet of gas left in his AL40 pony, instead of bobbing around the mid-Atlantic by himself at night, hoping the coast guard will find him and his two empty tanks before he makes it to Greenland.

By my calculation, an AL30 might or might not be big enough to ascend under control in an emergency from the deep end of recreational limits. Would an AL13 pony be better than nothing? You bet your butt it would. Would an AL13 be better than competitively priced alternatives? I don't believe so, but I'm open to arguments to the contrary.

Personally, the only things my AL19 gets used for is pressurizing my regs while I rinse them in the bathtub, or fishing my frisbees out of water hazards after I play disc golf.

No, No, No, No. Starts fine. Then goes to "lets assume you are a complete idiot" In which case you should just take your own life before even getting into the water. If you are diving to 120ft. You better know you have very limited time, you would look at your guage, you would have a turn around minimum. If your idiot of a DB runs after the lobster, you make for the surface using the last of your air and then your 13cf pony. Arrive at the surface and hope to make the boat. Next hope your DB surfaces soon or at the very least that he has a very attractive partner which you can console. lol

Duckydiver
12-18-2007, 20:51
I'm Looking into a 30cf pony. It seems it to be an apropriat redundant gas supply far most rec. diving I would be doing.

BSea
12-18-2007, 22:08
MSilva: Your calculations make sense with one caveat, primarily for those who read your post. That is that all, I mean ALL, SAC rate and gas consumption calculations are assumptions. Assumptions are necessary to do some kind of analysis. But, a wise diver never plans on having "just enough gas" to do the job.

That is why I almost always dive some kind of twin cylinder configuration. It may be manifolded doubles, or it may be independent doubles, or it may be a back mounted single with a slung tank. But, I always have way, way more gas on board than what I expect to need.

To me, the wise diver does something like what the airlines do. They plan for enough fuel to get to their destination and hang around for awhile, go to their alternate and hang around for awhile and then add in some more.

Or, another way: If you can't afford to buy big tanks, or aren't strong enough to handle them, you aren't wealthy enough, or strong enough to dive; period.

I agree with in general except for that last statement. I have a 120, and tanks ranging in size down to a few steel 72's. When I'm going on a basic get wet, no technical dive I usually use a 72. Why? Because it has way more air than I need for that dive. For most rec diving, an aluminum 80 is way more than enough. So there isn't a need for big tanks for the general diving public. Especially if they have something as a backup.

So your last statement just is a little narrow IMHO.

danielh03
12-19-2007, 00:44
This is all great food for thought! Just one thing comes to mind that not many ppl have touched on. If you are having to share air on a 19cf then YOU and YOUR DIVE BUDDY have really screwed the pooch somewere along the way! If you feel you need a RBS, would you dive with someone that does not have one?

texdiveguy
12-19-2007, 01:00
If you feel you need a RBS, would you dive with someone that does not have one?

Sure why not???

For recreational diving my RGS is my reserve gas source not my dive buddies....many of the guys I dive with recreationally carry a RGS themselves anyways....but if they don't that's really their issue not mine, can't hold everyone's hand.
:)

WD8CDH
12-19-2007, 09:17
Back when nobody was even knew what an octo was, I was diving with two second stages. When people started using an octo, I was using a spare regulator on a D size medical O2 tank with a SCUBA ost valve. I later went to an E size tank and then an aluminum 14 as soon as they became available. So yes, I like a Redundant Breathing System and only very rarely dive without one.

Now, I consider a 19 as the minimum, even when a 13 would be enough, because due to the same diameter of both tanks, the 19 is hardly any bulkier or much more expensive.

My most often used rig is triple 40s with two tanks as doubles and the third independant. That gives me 1/3 of my air supply as a Redundant Breathing System.

Iceman
12-19-2007, 12:08
Right in with this thread was a question I was asked yesterday. Like so many people who ask the question her mind set was to figure out the absolute minumum redundant air she needed for a dive.

So, I tried to explain that the real question isn't what is the minumum. It is with her physical ability what is the maximum she can carry. After a bit of conversation she understood that when all costs are considered it makes no sense to carry anything less than the maximum. Then the task is to fit the dive and all conceivable problems into that gas supply rather than the other way around.

She said: "Oh, I neve thought about it that way. But, it doesn't cost much more to be able to handle anything that comes my way. Maximum makes sense."

Now, if a brand new diver can figure that out why is it such a problem for so many who are more experienced?

MSilvia
12-19-2007, 13:38
If your idiot of a DB runs after the lobster, you make for the surface using the last of your air and then your 13cf pony.
In this scenario, the diver didn't see where his buddy went, so he didn't know he had been 'ditched' for a bug. Unfortunately, it isn't uncommon for instabuddies to be unreliable, and I specifically mentioned that this guy wasn't a great buddy. Given enough gas to make a quick search, would you advocate giving up on a buddy who isn't in sight, or is that only if you decide not to bring enough gas to leave you any margin of error? Personally, I like to leave myself enough wiggle room to deal with issues that may come up underwater, rather than planning for just enough to bolt in the most stressful way that could possibly be considered "safe". I don't understand why the other option would be better.

On the flip side of this coin, if you have an attentive non-idiot buddy you trust, and he brings enough gas to share air with you, what do you need the pony for?

Suddenly the "roomy" 19cf bottle is feeding two, and probably is not going to give enough gas. I carry a pony (as opposed to a stage) for self rescue, as a backup in cases where I don't feel I can count on a buddy to provide gas to me if anything goes wrong. IMHO if you're planning for what to do if you and your buddy both run out of back gas, you don't need a bigger pony... you need to learn basic gas management and buddy skills.

terrillja
12-19-2007, 13:50
If you have an attentive buddy you trust to share air with you, what do you need the pony for?


I think I may have been in the DAN report or somewhere else, but one of the most common causes of death while diving was sharing air with a buddy when the one sharing air is already low. If you both have similar SAC, you will both run out around the same time, then you share, kill the little bit of air you have left, then you have a double fatality at worst or near drowning at best. I personally dive a 30cf, and my dad dives the same.

I follow the rule that your best rescuer is yourself, as well as the rule that you do not put your self at risk to save another. If you are low on air and your buddy goes OOA, you would have to choose to risk both of your lives to help your buddy, or get yourself to safety. Not a decision I want to make, so I have the pony. I agree with what others have said here, when deciding on a pony, think of worst case, being used by 2 panicked divers, part of the reason I went with a 30.

If I did it again, I'd probably get a 40, pony tanks can be attached in lots of ways and you never notice them. A little piece of mind comes pretty cheap.

MSilvia
12-19-2007, 13:50
Only question I have is whether the reg is good enough. My primary is an Apeks XTX 100 and my pony is a Mares MR12 first with proton second.
I should certainly think it would be up to the job.

Navy OnStar
12-19-2007, 13:51
To me, the wise diver does something like what the airlines do. They plan for enough fuel to get to their destination and hang around for awhile, go to their alternate and hang around for awhile and then add in some more.

Not to get off topic, but the airlines carry a lot less fuel than you think. fuel is weight and weight costs money to transport so the airlines calculate down to a gnats a$$ and have a narrow safety margin. They would rather not take off than get put into holding or worse have to go to an alternate. That's why the delays are so huge.

They used to top off every where they went until they started losing money and some guy they brought in looked at all the factors involved in transporting passengers including the fuel and determined they could save hundreds of millions by cutting out the extra gas. So they operate closer to the "Just enough theory" than you may think.

Safety according to the almighty dollar!

MSilvia
12-19-2007, 13:53
If you have an attentive buddy you trust to share air with you, what do you need the pony for?


I think I may have been in the DAN report or somewhere else, but one of the most common causes of death while diving was sharing air with a buddy when the one sharing air is already low. If you both have similar SAC, you will both run out around the same time, then you share, kill the little bit of air you have left, then you have a double fatality at worst or near drowning at best.
That's an excellent reason for diving with turn pressures based on a rock bottom calculation. If you don't have enough gas left to rescue you and your buddy, you should already be back on the boat.

cgvmer
12-19-2007, 15:24
Also as a response to the OP, in some localities a redundant air supply is required before diving off many of the boats (NJ).

texdiveguy
12-19-2007, 16:40
Also as a response to the OP, in some localities a redundant air supply is required before diving off many of the boats (NJ).

Very good point!

Iceman
12-19-2007, 18:19
To me, the wise diver does something like what the airlines do. They plan for enough fuel to get to their destination and hang around for awhile, go to their alternate and hang around for awhile and then add in some more.

Not to get off topic, but the airlines carry a lot less fuel than you think. fuel is weight and weight costs money to transport so the airlines calculate down to a gnats a$$ and have a narrow safety margin. They would rather not take off than get put into holding or worse have to go to an alternate. That's why the delays are so huge.

They used to top off every where they went until they started losing money and some guy they brought in looked at all the factors involved in transporting passengers including the fuel and determined they could save hundreds of millions by cutting out the extra gas. So they operate closer to the "Just enough theory" than you may think.

Safety according to the almighty dollar!

Nope, they don't carry less fuel than I think. I'm intimately familiar with the rules; and the penalties for not following them.

Right on though that the expense side of the ledger is a bigger lever than it used to be. Hence, the 50# bag limit vs. 72#, and a "First Class" that isn't even as good as what Coach used to be. But, we digress excessively.

danielh03
12-20-2007, 03:18
Also as a response to the OP, in some localities a redundant air supply is required before diving off many of the boats (NJ).

Very good point!


I had no clue! But I have never been on a boad dive myself, and that would be a bad time to learn it. How much weight on average does a 19 cf add?

WD8CDH
12-20-2007, 06:43
Not including valve and regulator which would be about 2 or 3 pounds no matter what tank is used, a 13 is about 7 lb., a 19 is about 9.7 lb., a 30 is about 14 lb., and a 40 is about 18 lb. filled. All of the aluminum ponys are within a pound or two of negative buoyancy with valve and regulator so you can usually take a small amount of weight off.

I usually prefer the largest tank of a given diameter to keep a low profile so I use the 19 and the 40 the most.

BSea
12-20-2007, 08:46
How much weight on average does a 19 cf add?
About 12 to 15 pounds out of the water with a reg attached.

reeldive
12-20-2007, 09:19
I can remove 3-4 lbs when useing my 19 cf

MSilvia
12-20-2007, 09:33
I can remove 3-4 lbs when useing my 19 cf
Would that leave you underweighted if you tried to do a safety stop after breathing 10+ cubic feet out of it?

CompuDude
12-20-2007, 12:00
Not including valve and regulator which would be about 2 or 3 pounds no matter what tank is used, a 13 is about 7 lb., a 19 is about 9.7 lb., a 30 is about 14 lb., and a 40 is about 18 lb. filled. All of the aluminum ponys are within a pound or two of negative buoyancy with valve and regulator so you can usually take a small amount of weight off.

I usually prefer the largest tank of a given diameter to keep a low profile so I use the 19 and the 40 the most.

It's my understanding that weighting should be done without the presence of consumables such as pony's, which can be ditched, breathed down, or handed off, thus leaving you under-weighted.

in_cavediver
12-20-2007, 17:31
Not including valve and regulator which would be about 2 or 3 pounds no matter what tank is used, a 13 is about 7 lb., a 19 is about 9.7 lb., a 30 is about 14 lb., and a 40 is about 18 lb. filled. All of the aluminum ponys are within a pound or two of negative buoyancy with valve and regulator so you can usually take a small amount of weight off.

I usually prefer the largest tank of a given diameter to keep a low profile so I use the 19 and the 40 the most.

It's my understanding that weighting should be done without the presence of consumables such as pony's, which can be ditched, breathed down, or handed off, thus leaving you under-weighted.

My opinion is you do the weighting for all of the equipment you don't plan on losing and with dead empty tanks. You then look at the gear you might hand off/lose/drop and if its positive, then you have to add weight for it as well. Always do this for empty tanks.

For instance, if you don't plan on handing off a pony, you can drop its empty negative weight. IE, if its -3lbs when empty, take 3 pounds off you belt. Also, if its positive when empty, make sure to add that weight as well.

danielh03
12-21-2007, 00:56
Not including valve and regulator which would be about 2 or 3 pounds no matter what tank is used, a 13 is about 7 lb., a 19 is about 9.7 lb., a 30 is about 14 lb., and a 40 is about 18 lb. filled. All of the aluminum ponys are within a pound or two of negative buoyancy with valve and regulator so you can usually take a small amount of weight off.

I usually prefer the largest tank of a given diameter to keep a low profile so I use the 19 and the 40 the most.

It's my understanding that weighting should be done without the presence of consumables such as pony's, which can be ditched, breathed down, or handed off, thus leaving you under-weighted.

My opinion is you do the weighting for all of the equipment you don't plan on losing and with dead empty tanks. You then look at the gear you might hand off/lose/drop and if its positive, then you have to add weight for it as well. Always do this for empty tanks.

For instance, if you don't plan on handing off a pony, you can drop its empty negative weight. IE, if its -3lbs when empty, take 3 pounds off you belt. Also, if its positive when empty, make sure to add that weight as well.

Its amazing how much it can throw you off! I would hope that I never have to ditch something like that, but handing it off could be a reality. It might seem anal, but would it be a good idea for a diver to make a spread sheet, showing the amount of weight to add or take off for gear such as RBS?

CompuDude
12-21-2007, 01:53
It would indeed seem anal, but you won't get any judgment from me!

danielh03
12-21-2007, 12:46
It would indeed seem anal, but you won't get any judgment from me!

Yea, I guess your right! Better scrap it! lol:smilie39:

Hollywood703
12-27-2007, 12:35
I usually have a 30CF mounted with a octo on my right side.....I use an octo inflator, so if they come looking for my octo, they are not breathing off my tank unless i give them my reg.....I prefer to give them my redundant, and keep my own air.

WaScubaDude
12-27-2007, 18:05
I usually have a 30CF mounted with a octo on my right side.....I use an octo inflator, so if they come looking for my octo, they are not breathing off my tank unless i give them my reg.....I prefer to give them my redundant, and keep my own air.

If you read about most other diver OOA situations you will find the diver who is OOA will rip the reg out of the "donar's" mouth. So you might practice grabbin your octo or air II for your own benifit. my 2 psi.

danielh03
12-28-2007, 02:24
Ok, some ppl have stated that they "sling" a pony while others mount theirs. I would assume that you mount using a "quick draw" system so that you can detach it and pass it off. How does the "sling" work? wouldn't it get in the way?

charlesml3
12-28-2007, 09:33
I have some difficulty imagining why someone would opt for a 13 instead of a 19 or more.

I can carry a 13 in my carry-on and still be under the weight limit. I just can't take a bigger pony with me than that. My carry-on is right at 39 lbs.


If you feel you need a RBS, would you dive with someone that does not have one?

I sure better be OK with it. I'm the only one in my group that carries a pony.


Suddenly the "roomy" 19cf bottle is feeding two, and probably is not going to give enough gas.

Honestly, what are the odds of this actually happening? BOTH of you experience a catastrophic failure at the same time? I think this is just too unlikely to consider in your risk analysis.

The bottom line is this: There is no "perfect" size pony. You have to look at where you're diving, how you're getting there, how much weight you're willing to add and how much hassle you're willing to tolerate.

The argument "more is safer" doesn't really help. Not diving at ALL is "safer."

-Charles

Mtrewyn
12-28-2007, 10:26
I have some difficulty imagining why someone would opt for a 13 instead of a 19 or more.

I can carry a 13 in my carry-on and still be under the weight limit. I just can't take a bigger pony with me than that. My carry-on is right at 39 lbs.


If you feel you need a RBS, would you dive with someone that does not have one?

I sure better be OK with it. I'm the only one in my group that carries a pony.


Suddenly the "roomy" 19cf bottle is feeding two, and probably is not going to give enough gas.

Honestly, what are the odds of this actually happening? BOTH of you experience a catastrophic failure at the same time? I think this is just too unlikely to consider in your risk analysis.

The bottom line is this: There is no "perfect" size pony. You have to look at where you're diving, how you're getting there, how much weight you're willing to add and how much hassle you're willing to tolerate.

The argument "more is safer" doesn't really help. Not diving at ALL is "safer."

-Charles

I agree I think you just have to play the odds and go with what works best and fits you. It would be very easy to go overboard with this, or you could just stay dry.

danielh03
12-28-2007, 19:49
I have some difficulty imagining why someone would opt for a 13 instead of a 19 or more.

I can carry a 13 in my carry-on and still be under the weight limit. I just can't take a bigger pony with me than that. My carry-on is right at 39 lbs.


If you feel you need a RBS, would you dive with someone that does not have one?

I sure better be OK with it. I'm the only one in my group that carries a pony.


Suddenly the "roomy" 19cf bottle is feeding two, and probably is not going to give enough gas.

Honestly, what are the odds of this actually happening? BOTH of you experience a catastrophic failure at the same time? I think this is just too unlikely to consider in your risk analysis.

The bottom line is this: There is no "perfect" size pony. You have to look at where you're diving, how you're getting there, how much weight you're willing to add and how much hassle you're willing to tolerate.

The argument "more is safer" doesn't really help. Not diving at ALL is "safer."

-Charles

I agree I think you just have to play the odds and go with what works best and fits you. It would be very easy to go overboard with this, or you could just stay dry.

Well, everytime I go diving I go "overboard". If I didn't, I would never get in the water :smilie39: But I see your point. Yes, you can go overboard with your RBS, but diving is about safety/danger. You have to balance them to the best of your ability. Will I have a RBS by next dive season, yes. Will it be a 30 CF, no. I plan on me OR my buddy running out of air or a free flow, not both of us. :smiley21:

MSilvia
12-28-2007, 20:23
I plan on me OR my buddy running out of air or a free flow, not both of us. :smiley21:Good plan, until you and your buddy both have a free flow. It's not likely though... it's only happened to me once. Fortunately, it was a relatively shallow dive, and we both kept breathing off the free flowing regs until we were back at the surface and could shut the valves on our non-redundant single tanks. It's probably not a problem you'll have in TN and points south.

danielh03
12-28-2007, 22:46
I plan on me OR my buddy running out of air or a free flow, not both of us. :smiley21:Good plan, until you and your buddy both have a free flow. It's not likely though... it's only happened to me once. Fortunately, it was a relatively shallow dive, and we both kept breathing off the free flowing regs until we were back at the surface and could shut the valves on our non-redundant single tanks. It's probably not a problem you'll have in TN and points south.

I don't normaly get into water below 50 deg. and I am a "seasonal" diver lol. Also, I have a pretty good reg set, thanks to Joe, that I feel can handle colder temps if I need them. So unless I have a gear failure or something just sticks, I hope to never use my RBS!:smiley2: