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Pony Bottle?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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kenmx10

New Member
Aug 20, 2017
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Hi, For the past 10 years or so Ive been going down to the keys and Grand Cay Bahamas , 2 or 3 times a year, spearfishing and collecting lobster. I prefer free diving over scuba while spearfishing. Usually we are limited to 20 to 30 foot depths because we always have a couple newcomers with us who usually can't get down past that their first time. A lot of times Ill swim the deeper side of the ledges while they stay in the shallower water, and I end up getting in some 40 or 50 feet drops. While I have a certificate from PADI as a rescue diver, I have no professional training in free diving.

So here is my question, Ive been thinking about doing something and would like to get some professional opinions incase its a bad idea. I am thinking about getting a 13 cf pony bottle , with a harness and regulator, and having it on while free diving(spearfishing). The reason is not to scuba dive on a pony bottle ,but to be able to take a couple breaths and stay down a minute or so longer if I see a nice fish run under a rock, or have to chase him down. I know that lung over expansion would occur if you didn't exhale before you started to ascend. So my thoughts are to always exhale before ascending. Being that I'm only taking a couple breaths off it at a time, occasionally, not using it constantly as with scuba , I wouldn't think nitrogen would be an issue because I would be free diving, and still spending more time at the surface swimming around looking down for fish than I would be underwater.

On the other hand, I don't hear anyone else doing it , and don't see any equipment one the market to support this kind of behavior. So I question if it is a good idea and realize there might be some dangers that I have not considered. Any thoughts would be greatly appreciated.
 
I wouldn't do it if I were you. I have plenty of experience at both free diving and scuba. I scuba dove from 1954 to 1996 including US Navy scuba school and I've been free dive spearfishing since 1996, but I still wouldn't trust myself to keep clear on what I was doing. You would be on what was primarily a free dive but then mixing in a bit of scuba. you might be excited about shooting a big fish and forget to exhale.

I carry 9 cubic foot and 13 cubic foot pony bottles on my boat to use when an anchor is hung in the rocks or a fish it tied up too deep for safe freediving. I very seldom use one, although on my last trip I did use one to cut a fish out of the kelp on the bottom. But when I do use one, I lecture myself about remembering that I'm on a scuba dive this time. But at least my dive is scuba from start to finish. I wouldn't trust myself to mix the two.

You mention equipment. I use a backpack from Sea Soft. It has a quick release compartment in the bottom for weights but I don't use that. I just wear my regular freedive weight belt.
Ponybackpack.JPG
 
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Thx for the advice Bill. I like your Sea Soft rig. Ill have to see about getting one of those.
 
Thx Bill. Im not concerned about forgetting to exhale. I know Its something I can do without forgetting. What I am curious about is if the change from holding your breath, to taking in some air could possibly cause an increase in inner ear pressure and cause damage to eardrums. I would think as long as your equalized it shouldn't matter, but have not tried it to know for sure. I would like to hear from someone that has dived with A Hookah rig , and dived down 30' then took a breath.
 
As long as your eustachian tubes are clear I don't think you'll have any problem. Its just like ascending in an airplane, although of course with much more rapid pressure changes. When I attended US Navy Underwater Swimmer school, we made free ascents from as deep as 100 feet in the escape training tower. Of course we weren't using a pony bottle, but the effect was the same. We were taking a breath of air at ambient water pressure before stepping out of the lock. I didn't have any ear problems, and I can't recall anyone else in the class having them.

In my experience you are more likely to have a problem with sinuses during ascent. If you have a cold and the tissue lining the sinuses is inflamed, it can cover the opening and prevents the expanding air from escaping. That happened to me at the end of that diving course. I was diving with a very bad cold but didn't want to drop out of the course. As I started an ascent after a search for a limpet mine on the hull of a Navy ship, I had excruciating pain until the sinus finally blew tissue and blood out.

And when I later became a jet fighter pilot, and I had similar experiences when flying with a bad cold. A couple of times while climbing to altitude my ears had no trouble letting the air out of the middle ear, but the air couldn't get out of my sinuses. When the pain got extreme, I had to stop the climb and go back and land. You can always quit climbing in an airplane, but eventually you have to come up from a dive.
 
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Thx Bill. Im going to the Keys in a few weeks so I think I might pick up a 100' hose and hook it up to a tank and try it out. If there are no problems I might get a pony rig like you have and try it out very cautiously .Maybe starting at 10' , then 20' and then 30'. Stop there and analyze the experience to see if its worth pursuing or not .
 
On the other hand, I don't hear anyone else doing it , and don't see any equipment one the market to support this kind of behavior. So I question if it is a good idea and realize there might be some dangers that I have not considered. Any thoughts would be greatly appreciated.
What you are proposing falls into the category of experimental diving. I have done similar experiments, and I know of some others who have done dives similar to what you are proposing as well.

There are dangers, as with any form of diving. The biggest difference here is that you can't go to someone for knowledge and training on the subject. You get to be the lab rat in your own experiments. That's where the real danger lies; not in the fact that you are hybrid diving, but in the fact that you are conducting experiments to learn techniques to conduct a new and not well understood form of diving. If you already knew how to do it safely, it would not be dangerous. The question is, "How do you learn how to do it safely without getting hurt in the process?".

Another barrier is that the few people who do experiments like you are proposing don't talk details online. We don't know everything and can't provide competent and thorough advice. Therefore we don't want to provide it, especially in an open online forum where anyone could be reading and getting ideas in there head that may actually be quite bad for them.

If you pursue this, you're going to have to execute your own learning plan. The only real advice I can offer is to encourage you to think about what you are doing a lot before you act, and take small steps to, hopefully, minimize the consequences of unknown-unknowns as they become known to you. Experimental diving can be dangerous, so think about contingencies and have help ready to deal with emergencies.
 
Last edited:
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Hi, For the past 10 years or so Ive been going down to the keys and Grand Cay Bahamas , 2 or 3 times a year, spearfishing and collecting lobster. I prefer free diving over scuba while spearfishing. Usually we are limited to 20 to 30 foot depths because we always have a couple newcomers with us who usually can't get down past that their first time. A lot of times Ill swim the deeper side of the ledges while they stay in the shallower water, and I end up getting in some 40 or 50 feet drops. While I have a certificate from PADI as a rescue diver, I have no professional training in free diving.

So here is my question, Ive been thinking about doing something and would like to get some professional opinions incase its a bad idea. I am thinking about getting a 13 cf pony bottle , with a harness and regulator, and having it on while free diving(spearfishing). The reason is not to scuba dive on a pony bottle ,but to be able to take a couple breaths and stay down a minute or so longer if I see a nice fish run under a rock, or have to chase him down. I know that lung over expansion would occur if you didn't exhale before you started to ascend. So my thoughts are to always exhale before ascending. Being that I'm only taking a couple breaths off it at a time, occasionally, not using it constantly as with scuba , I wouldn't think nitrogen would be an issue because I would be free diving, and still spending more time at the surface swimming around looking down for fish than I would be underwater.

On the other hand, I don't hear anyone else doing it , and don't see any equipment one the market to support this kind of behavior. So I question if it is a good idea and realize there might be some dangers that I have not considered. Any thoughts would be greatly appreciated.

Please don't do this.

The natural air in your lungs contain oxygen which your body relies on.

When we dive, we are taught to never exhale underwater, because even in the last moments before surfacing, the air in our lungs still contain oxygen (even if its saturated with co2 buildup).

By taking gulps from the pony tank, you have switched yourself into a scuba diver,and you will need to follow the rules of scuba, in a slow ascent and a exhaling as you ascent.

The problem is, you will lose your oxygen reserve by letting the air from you lungs out. You increase your chances of a blackout.

Your pony tank may not have enough air to take you up.

Stay safe! We all would love to see you continue to enjoy the ocean but not at the expense of your life!
 
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The problem is, you will lose your oxygen reserve by letting the air from you lungs out. You increase your chances of a blackout.
That's not how it works. BO is driven by low Partial Pressure (PP) O2 in the lungs, not by low Mols O2 in the lungs. Exhaling/venting doesn't intrinsically change the PP O2. PP O2 only changes by changing the total pressure, by gas exchange within the lungs, or by ventilating with a gas of different O2 content. Tanking in gas from a scuba tank will periodically raise the PP O2 at any given depth and decrease the chances of BO, especially if that tank contains an enriched nitrox mixture.
 
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