Free-Diving Mixed/with use of Pony System

[FrankPro1]

I know of the inherent risks of free-diving after a scuba session, but my question is a little different. I was wondering if it would be dangerous to use a pony system to do a short/shallow 5 minute scuba dive during a shallow snorkel/free dive. I've been getting addicted to underwater photography and can think of a few instances when I couldn't quite get the perfect shot because of my lack of lung capacity. I just upgraded my regulator and was thinking of purchasing redundant systems for deep/solo dives but was wondering about the use during snorkeling.

 

[Venus]

CAGE comes to mind, I wouldn't do it

I was wondering if it would be dangerous to use a pony system to do a short/shallow 5 minute scuba dive during a shallow snorkel/free dive.

Solo diving on 0-24 dives?

 

[FrankPro1]

CAGE comes to mind, I wouldn't do it

Solo diving on 0-24 dives?

Though solo diving has sparked my interested I am def. not going to do any soon, but getting redundant systems would be great for deeper, advanced dives "just to be especially safe". What is CAGE?

0-24 scuba dives..... I've got at least a hundred or more free-dives. But.... I know that doesn't count.

 

[bleeb]

Not the first time this general topic has come up before.

I'm not an expert, but my opinion is that if you breathe compressed gas, it's a dive. You on-gas nitrogen and have to off-gas it, although the amounts are relatively small. You're at risk of embolism if you ascend incorrectly. (Remember that it only takes 3-6' of water to embolize.) If anything, the chances might actually be slightly higher if you were to go into the situation breathe-hold diving and then starting to breathe off the bottle at the bottom. And as you sort of implied in your OP, with multiple pressure cycles with nitrogen loading, there's the risk of pumping microbubbles from the venous side of your blood system to the more dangerous arterial side, although again, I suspect the risks are low given the small amounts of nitrogen you're talking about.

That being said, to me, multiple short/shallow dives like you described are not necessarily unacceptable. There are additional risks and it's mostly in how you recognize and manage them.

 

[Katamuki]

I set anchors on boats with a pony slung on a front harness all the time. I do wear weights and follow normal ascent rules though as it is still compressed gas I'm breathing. It is still a bounce dive if you think your going to go up and down in the water column taking pictures though and not like an anchor were its once down and up in less than 12 meters of water generally.

 

[Venus]

Hi Frank

I like diving with a pony to the point that I take it overseas with me now if I can not rent one on the liveaboard

I certainly support carrying redundant air as part of a scuba dive

My comment was not about nitrogen loading, not sure if this can happen on these short, shallows dives as you explained above .... can someone more qualified answer this

 

[Venus]

CAGE = cerebral arterial gas embolism

I may get it wrong if I try to summarise it myself, so this is an extract from the London Hyperbaric web site

Pulmonary overpressurisation, for example during a breath holding ascent, can cause large gas embolisation when rupture into the pulmonary veins allows alveolar gas to enter systemic or arterial circulation.

Gas emboli can lodge in coronary, cerebral, and other systemic arterioles. These gas bubbles continue to expand as ascending pressure decreases, thus increasing the severity of clinical signs.

Symptoms and signs depend on where the emboli travel. Coronary artery embolisation can lead to myocardial infarction or abnormal rhythms. Cerebral artery emboli can cause stroke or seizures

There is a lot of very good information on this website

 

[FrankPro1]

If anything, the chances might actually be slightly higher if you were to go into the situation breathe-hold diving and then starting to breathe off the bottle at the bottom.

I wouldn't be trying that... Just a simple down say 15-20ft for 5 or so minutes and then ascend at a safe rate.

I do wear weights and follow normal ascent rules though as it is still compressed gas I'm breathing. It is still a bounce dive if you think your going to go up and down in the water column taking pictures though and not like an anchor were its once down and up in less than 12 meters of water generally.

Would absolutely be wearing weights and follow normal ascent rules. Would generally want to go down, stay at depth and then ascend. No up down, up down in the water column. From there just continuing shallow free-dives "less the 30ft".

 

[ianr33]

. What is CAGE?

Cerebral Arterial Gas Embolism

Guess I need to type faster!

 

[Gary D.]

You can take as much or as little air as you wish on a dive as long as that air is approate for what you are doing. Anytime you ingest air underwater as life support it becomes a dive. There have been many times (mostly training) where I have free dove to a diver, got a breath or two then gone onto another and so on for some extended dives. They knew before hand that was going to happen so I didn't alarm anyone. Keep in mind that I don't recommend this to anyone trained in recreational diving. The point is that it is still a dive gear or no gear and has to be treated as such. It doesn't matter if it's a lot of air or just a little the dive still needs to be within your limits and safely.

Gary D.