Hello! New to the forum, researching redundant air options :)

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Dan_vG

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Hi all,

I've been reading threads on this forum for quite a while, never posted until now, but thought I'd say hi as I've been browsing here quite a bit lately. It's been extremely educational to follow conversations here and I've gained a ton of insight; this is an awesome community.

I've been diving for four years, having gradually worked my way through various PADI certifications to now being a master scuba diver. I've done a little over 100 dives. While Cozumel may be my favorite dive location so far, I've also especially enjoyed doing cold water dives.

Since the pandemic has made travel more challenging, I'm considering getting more invested in local diving (I'm based in Chicago), especially trying to get some experience in deep dives. There are some wreck dives in Lake Michigan at ~120ft that seem pretty great, and I'd love the experience.

I've done a fair amount of dives around the ~90ft mark (most in warmer water, though also some in Lake Michigan) and I have quite a bit of experience diving in cold water (e.g. Portugal, Iceland, Alaska) but not as deep. The combination of the two has me wondering if I should be more/better prepared and look at additional equipment. I've been trying to do some research on redundant air sources - I'm on the fence about getting a pony bottle if I'm going to be doing dives at 120ft. It seems like a lot of extra cost and hassle, but there's a big "better safe than sorry" element.

I will continue to read up on threads here and am excited about tapping into the wealth of knowledge and experience of folks on here!
 

boulderjohn

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Well, I was going to leave this alone, but as you have gone about 24 hours without a response, I will kick in.

This is the kind of thread that can go two entirely different ways, depending upon who reads and reacts first. You might get a totally different sense of the community from this than you would if your wrote the same post a week later. As Woody Allen said, "History is made by those who show up."

Quite a few people will absolutely swear that you need to have a redundant air source at that (or any depth), and the discussion from there will be "what redundant air source should that be?" Others will say, "Nah, you don't need that. Just be aware of your gas supply." Both will sound rational.

Not much help, huh?

As for me, I rarely use a true redundant air source on recreational dives to any depths, but i do sometimes carry something in that ballpark, an extra tank I can use for decompression (say 50% O2) but can actually also use fairly deep in an emergency. I have that because I happen to have it around for decompression diving and I figure, what the heck, bring it along.

If you are on the fence, my recommendation would be to use one. Better safe than sorry, as you said. Which one? I think you should look to the future. Is there any possibility at all that you might be going into tech diving? If so, then the choice would be an AL 40, because that is very useful on tech dives. Check out prices, and you will see that the difference in price between an AL 40 and an AL 19 is not very much.

You are very close to Dive Right in Scuba. You can get good advice there.
 

drrich2

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The combination of the two has me wondering if I should be more/better prepared and look at additional equipment. I've been trying to do some research on redundant air sources - I'm on the fence about getting a pony bottle if I'm going to be doing dives at 120ft. It seems like a lot of extra cost and hassle, but there's a big "better safe than sorry" element.

A couple of questions that might help inform the decision in the context of the diving you do.

1.) Do you do any diving functionally solo? In other words, either alone, or with unreliable buddies, or as an unstructured group dive where people often go their own way? In other words, in the event your primary gas supply stops for whatever reason and you're 120-feet deep...then what?

2.) What would you like this secondary air source to do? At one end, the Spare Air 3 is very compact and convenient...but basically gives you several breaths deep so your ascent isn't hurried. Don't count on making it all the way through a safety stop from a deep dive, and as for re-tracing your path to a point of entry, or 'rock bottom' type calculation/practices? No. But likely to be taken with you, travels easily and convenient. At the other end, some dive doubles. Big gas supply...but heavy and inconvenient. Somewhere in the middle, various sizes of pony bottle.

I get that in a perfect world we'd have Spare Airs with 100-cf of gas, but that's not the real world. Sounds like you've got an interest in a pony bottle. What would you like this pony to do? Get you to the surface slowly with a safety stop...or let you retrace your dive path back to a point of exit, in the event the surface overhead isn't safe (e.g.: frequent boat traffic)?

Two issues are often at odds...you need enough gas to serve the purpose, in a package you will actually take on the dive. So you are a key part of the question.
 

wetb4igetinthewater

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I believe in redundant air because:
1. buddy separation happens
2. catastrophic gas loss can happen.

It is EXTREMELY unlikely that both will happen at the same time. I had some bad experiences during my AOW course that led me to such caution as my instructor was a complete clown.

Other folks say they will conduct an emergency swimming ascent. Many have done so a number of times (I suspect mostly during the years of j valves). It depends on what level of risk you wish to take.

If you are interested in how to estimate what sized pony would get you to the surface, you may want to work with the numbers in this spreadsheet: AscentRateWithRedundantAirSource.xlsx
 

SlugMug

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I do mostly solo-diving, and in the interest of being able to handle emergencies I've been researching redundant-air-supply for the last couple days, and read a bunch of threads on the topic & even started a thread. This is not based on my personal experience, so take it with a pinch of salt-water.
  • 6cu - Somewhat useless & a waste of money, except at shallow depths. At depth, it's barely better than nothing, and may prevent drowning on a rapid ascent.
  • 13cu - at about 120ft is small drowning-risk, but medium decompression-risk.
  • 19cu - at about 120ft is negligible drowning-risk, but small decompression-risk.
  • 30cu & 40cu at about 120ft is negligible decompression-risk.
On the flip side is convivence:
  • 13cu - The spare pony-tank you have on you, is better than the one you leave at home, or on the boat.
  • 19cu - Probably ideal balance of weight, size, and risk-mitigation. It's also good for travel. Since this is just for super-rare emergencies, light decompression-sickness when diving near recreational-limit is probably tolerable.
  • 30cu - Good, but might as well go 40cu
  • 40cu - Best for multi-use, such as tech-diving, an extra/spare tank for short/shallow dives, resale-value, or even extending dives.
  • 80cu - You could always side-mount 2x 80s, and just always make sure to leave enough air on both for an ascent. That said, I'd be tempted to leave the 2nd 80 cu on the boat, or at home.
  • I'm currently leaning towards 40 cu for multi-use. However, 19 cu is also very tempting, and probably what I'd roll with if I owned both a 40 cu and 19 cu. In terms of mounting, most people recommends a side-mount for the pony.
Now, if you intend to do a LOT of 120ft diving, you go through air quickly, and might want to consider consider dual-side-mount 80s. Switch-regulators occasionally, and make sure you leave enough gas in each tank to safely surface. If you need more info, the solo-diver forum (for redundant air-supply questions) or side-mount forums are great places to ask.
I'm on the fence about getting a pony bottle if I'm going to be doing dives at 120ft. It seems like a lot of extra cost and hassle, but there's a big "better safe than sorry" element.
How much do you (and your employer) pay each month for health-insurance? Don't answer here of course, but think of this like a health-insurance policy. Even if you don't drown and die, you could face various other medical issues and pain, because you had to surface VERY quickly.

Since this is just a redundant air-supply, you could go with a very cheap regulator, or a used one (~$100). Install a mini spg like this one ($15), and a new 19cu tank (~$150), some hardware for a side-mount ($20 to $50) and you have a redundant supply for less than $300. Obviously, you can spend more and get nicer equipment, but this is just a spare you're not intending on using except in emergencies.
 

Tripp

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Howdy and Welcome to SB from Texas!!! Dive right in the water's fine!! I will be reading all of the responses here.
 

SlugMug

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Howdy and Welcome to SB from Texas!!! Dive right in the water's fine!! I will be reading all of the responses here.

Thanks! Not to topic drive, what's your favorite dive spot near San Antonio?
 

Gone for diving

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I think if you get a pony, might as well get a 40 aluminum... that's what I got when I started. And am happy I did.... it is a bit more work in a small boat especially at first... someone handing it to you etc.
But how many times on deeper stuff with a doubles or single half or less empty... take the 40cu. And you'll have lots of cushion...
It's also great when you're not sure your going to dive like at a beach or something... take your mask fins and 40cu. No mount it... actually quite fun. And you have a useful supply of air...
 

Scuba Client

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Hi all,

I've been reading threads on this forum for quite a while, never posted until now, but thought I'd say hi as I've been browsing here quite a bit lately. It's been extremely educational to follow conversations here and I've gained a ton of insight; this is an awesome community.

I've been diving for four years, having gradually worked my way through various PADI certifications to now being a master scuba diver. I've done a little over 100 dives. While Cozumel may be my favorite dive location so far, I've also especially enjoyed doing cold water dives.

Since the pandemic has made travel more challenging, I'm considering getting more invested in local diving (I'm based in Chicago), especially trying to get some experience in deep dives. There are some wreck dives in Lake Michigan at ~120ft that seem pretty great, and I'd love the experience.

I've done a fair amount of dives around the ~90ft mark (most in warmer water, though also some in Lake Michigan) and I have quite a bit of experience diving in cold water (e.g. Portugal, Iceland, Alaska) but not as deep. The combination of the two has me wondering if I should be more/better prepared and look at additional equipment. I've been trying to do some research on redundant air sources - I'm on the fence about getting a pony bottle if I'm going to be doing dives at 120ft. It seems like a lot of extra cost and hassle, but there's a big "better safe than sorry" element.

I will continue to read up on threads here and am excited about tapping into the wealth of knowledge and experience of folks on here!
The best advice I can give you is to be a team player. Every piece of scuba equipment should adhere to the terminology that dive equipment is life support.
 

Bob DBF

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Considering where you are, pick up a 40. If you like diving on the local wrecks it will save you a purchase when you go tech. If not, it will give you the best resale should you decide on a smaller pony. In the mean time you will be packing around a lot of air if things go south.

This is not my usual advice, but from you are not the usual profile asking.
 
https://www.shearwater.com/products/teric/

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