What was the most influential development in scuba diving?

[happy-diver]

still happening where I'm at

it's

scary

any wonder I wet the bed again or is that something else

 

[AfterDark]

still happening where I'm at
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it's
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scary
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any wonder I wet the bed again or is that something else

AQUALUNG LIVES!!!

 

[Joris Vd]

I'm very surprised at how few people voted for the octopus.

Before the octopus, if you had a second stage failure you would die basically if you didn't have a buddy near you.

 

[AfterDark]

I'm very surprised at how few people voted for the octopus.

Before the octopus, if you had a second stage failure you would die basically if you didn't have a buddy near you.

I'm not, it's probably the least used piece of gear owned by any diver.
I couldn't put an octopus on my double hose when I started diving. After buying a single hose regulator I dove without an octopus because the concept hadn't become popular yet. When the idea finally came into vogue I decided it wasn't worth the cost since I'd been fine without one for more than a few years already. I didn't add a octopus to my rig until I started diving with those without buddy breathing training and "needed" an octopus in case of a failure. Personally I've never experienced a failure to deliver air from a single hose regulator. There was a failure of a loaned double hose that left me without air @70FSW a CESA was my remedy to that OOA episode. Twenty years later I needed to buddy breath at the last deco stop @10FSW which was excepted because of changes made to the dive plan on the fly. I still live!!
The octopus is the last thing I would pick.

 

[Angelo Farina]

The question is whether or not CCR's are going to become affordable enough to be that widespread. My entire OC dive set up has cost under $2,500 and the cheapest CCR I've ever seen was about twice as much at $5,000 not to mention exposure suits, computers etc.

When I started diving, in the seventies, CCRs were significantly CHEAPER than compressed-air OC scuba systems, at least here in Italy. And that was the reasons for which all diving schools were using CC rebreathers for teaching to new divers. Only after months of training with those cheap and crap rebreathers the few students who did not give up were given air tanks (of course twin tanks, with double valve plus reserve, two complete independent regulators, no SPG and no BCD).
Then the price of air systems started to decrease, and more modern (but expensive) rebreathers were introduced.
I do not see how this tendency can be reversed: I think that also in the future rebreathers will continue to grow even more expensive than OC systems.

 

[Akimbo]

When I started diving, in the seventies, CCRs were significantly CHEAPER than compressed-air OC scuba systems, at least here in Italy.

That is surprising. I don't think pure Oxygen rebreathes were ever cheaper in the US than open circuit. Of course Italy had a manufacturing infrastructure for them and rebreathers were only hand-built for the military in the US (outside of the mine safety market).

Italy was a leading manufacturer of regulators and Scuba cylinder valves by 1970. Were there high tariffs on high pressure cylinders?

 

[Angelo Farina]

That is surprising. I don't think pure Oxygen rebreathes were ever cheaper in the US than open circuit. Of course Italy had a manufacturing infrastructure for them and rebreathers were only hand-built for the military in the US (outside of the mine safety market).

Italy was a leading manufacturer of regulators and Scuba cylinder valves by 1970. Were there high tariffs on high pressure cylinders?

In 1975 the Cressi ARO 57B, the basic pendular CC rebreather used in diving schools, had a list price of 500,000 £, but diving schools could purchase it for 350,000. A standard twin tank (10+10 liters, 200 bars, steel, with double valve, reserve and harness) was ranging between 300,000 and 350,000 £.
You had also to buy two complete regulators, such as a Scucapro MK5+109, which were 200,000 £ each. In some diving schools they did save some money using just one reg, but still the OC system was costing almost twice than an ARO.
Also in terms of operational cost the ARO was cheap. We were using industrial-grade oxygen and soda lyme, so recharging a rebreather did cost around 10,000 £. But it did last for 4 to 6 hours, meaning at least 4 dives (the last one with significant headache if the student did not learn yet to breath properly, due to exhausted scrubber).
Filling the twin tank was typically 5000 £, but it did last 1 h only, and you need to fill again before each dive.
And finally an ARO CC was much smaller and lighter than a twin tank. Rebreathers were very female-friendly...
My wife (at the time she was my girlfriend) did love the rebreather, both outside water and underwater, as it was light and not bulky. And it did allow her to be perfectly neutrally buoyant, swimming with minimal effort.
The switch to OC systems was a big step for her: luckily she was strong enough for being able to fit the twin tank on her shoulders passing it over her head, which was one of the skills required at the final exam of the course. But many other students with tiny body were struggling raising a twin tank weighting more than 25 kg above their head...

 

[Akimbo]

@Angelo Farina

I never doubted the accuracy of your cost estimates, I'm just wondering what factors caused such a difference. Was there a regulator on the Cressi ARO 57B or did you manually open an HP valve to replenish the bag?

For other readers:​

Pure oxygen rebreathers of that era were little more than a rubber bag, harness, absorbent canister, HP Oxygen cylinder, 1-2 courigaged hoses, a mouthpiece, and some mushroom check valves.

From a manufacturing cost perspective, they were a tiny fraction what we think of today as a rebreather. No electronics, diluent, second bag, alarm lights, backup gas, or concern over decompression.

 

[AfterDark]

@Angelo Farina

I never doubted the accuracy of your cost estimates, I'm just wondering what factors caused such a difference. Was there a regulator on the Cressi ARO 57B or did you manually open an HP valve to replenish the bag?

For other readers:​

Pure oxygen rebreathers of that era were little more than a rubber bag, harness, absorbent canister, HP Oxygen cylinder, 1-2 courigaged hoses, a mouthpiece, and some mushroom check valves.

From a manufacturing cost perspective, they were a tiny fraction what we think of today as a rebreather. No electronics, diluent, second bag, alarm lights, backup gas, or concern over decompression.

Just how deep could a diver go with one of these beauties?

All the way to the bottom...once.

 

[Akimbo]

Just how deep could a diver go with one of these beauties?

Many of the world's navies' combat swimmers use pure O2 rebreathers, including US Navy SEALs. Most set a max depth at 20'/6M for a 1.6 PPO2 but most of the dive is shallower.

Of course they are in great physical condition and not working very hard (by their standards).