What was the most influential development in scuba diving?

[AfterDark]

Try diving without a SPG by calculating your planned depth and bottom time knowing you only have a single steel 72 cubic foot tank rated service pressure at 2250.

Dove that way for about 10 years when I started.

 

[AfterDark]

Lots of people saw it:

Electrolung

The GE Mark 10 was operational several years later.

What year was that? Was it 1998 or is that the date of the writing? I ask because 1998 falls short of the 50 years I mentioned. Those don't look microchips to me. More like transistors, chips were still a long way off. Just like the technology that will make CCRs common place someday, a long way off and unknown to us at this time.

 

[tursiops]

What year was that? Was it 1998 or is that the date of the writing? I ask because 1998 falls short of the 50 years I mentioned. Those don't look microchips to me. More like transistors, chips were still a long way off. Just like the technology that will make CCRs common place someday, a long way off and unknown to us at this time.

Pretty interesting history in Wikipedia under Integrated Circuit.
Precursor ideas were proposed in 1957, and a better version in 1958, patent in 1959. The monolithic chip came along in 1959, and NASA's Apollo used many of them in 1961-1965. TTL ICs came along in the early 1960s, and became dominate in the 1970s. The MOS transistor (Bell Labs, 1959) became MOS ICs in 1962.
50 years ago the whole IC technology was well established and well-used.

 

[lowwall]

What year was that? Was it 1998 or is that the date of the writing? I ask because 1998 falls short of the 50 years I mentioned. Those don't look microchips to me. More like transistors, chips were still a long way off. Just like the technology that will make CCRs common place someday, a long way off and unknown to us at this time.

According to Rebreather History: From Conception to the Modern Era (1680-2012) - DIVER magazine

"1969: Walter Stark introduces the ‘ElectroLung’ mixed gas rebreather for $2,500, subsequently bought by Beckman Instruments. Beckman shuts down division in 1970 after a number of fatalities."

Why does it matter that it used discrete transistors (and other electronic components) instead of the integrated transistors (and other electronic components) that are used in microchips?

 

[Akimbo]

What year was that? Was it 1998 or is that the date of the writing?

That was the date it was written. This was written farther down in that article:

Development of the Electrolung came about through the chance meeting of John Kanwisher and I aboard Ed Link's diving research vessel in the Bahamas in early 1968. Ed was trying out his new diver lock-out submarine Deep Diver and had invited along several researchers with relevant interests.

I remember reading about it in the late 1960s in Skin Diver Magazine. Beckman Instruments purchased it, who was a leading manufacturer of CO2 and O2 analyzers at that time. Teledyne eclipsed them in the Oxygen analyzer market within a few years. There is probably more to that story but I don't know the details.

Electrolung: The First Mixed Gas Rebreather Was Available to Sport Divers in 1968

While today mixed gas rebreathers are a standard tool for tech divers, it’s easy to forget that this enabling, underwater life support technology has been more than 50 years in the making. In fact, the first commercially available unit was available to sport divers in the late sixties! Here...

gue.com

It seemed to disappear after Bill De Court, a fairly well known diver, died wearing one in 1970.

FindLaw's California Court of Appeal case and opinions.

FindLaw's searchable database of California Court of Appeal decisions since

caselaw.findlaw.com

 

[Akimbo]

Why does it matter that it used discrete transistors (and other electronic components) instead of the integrated transistors (and other electronic components) that are used in microchips?

Conceptually it is not that big a factor but practically it makes a huge difference in the ability to apply logic and polling to test sensors against each other. The Electrolung was the first functional mixed gas (HeO2) eCCR. Even though it was not a success in the market, it was a true pathfinder.

The rest of the puzzle was required, which includes decompression technology. Navy and commercial bounce mixed gas tables were horrible at best, well into the 1990s. It largely became academic since saturation diving took over military and commercial deep work. It is ironic that deep trimix is primarily used for recreation today.

There has been rumors that US Navy divers locked out of a submarine in the late 1960s with an Electrolung but I doubt that very much. The state of saturation diving technology was pretty primitive at that point. The first Ivy Bells dives weren't until late 1971 using Westinghouse Mark 11 "Abalone" mechanical SCRs.

 

[Angelo Farina]

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.

???
Before the octopus, we were using two full regs (which I continued to use also after the crap idea of using just one first stage for feeding both second stages was developed).
The octopus was the way for reducing costs for training centers working for-profit, saving on the cost of (twin) tanks with double valves, which were the norm before the success of commercial diving agencies.

 

[Angelo Farina]

@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.

The Cressi ARO 57b was even simpler: a rubber bag, a filter, a single corrugate hose and a 1.5-liters oxygen tank with a manual "press to erogate" valve.
Maxiumun depth was 18 meters, but for a very short time.
Below 10m there was a sharp "safety curve", allowing for a max exposure time quickly diminishing with depth.
My first-level certification did not allow for this, max depth with the oxygen rebreather was 10m (and max depth with OC air was 15m).
The following years you had the second and third level certification, allowing you to dive deeper. Only with third-level you did get full recreational certification, allowing to use that "safety curve" down to 18m in pure oxygen and down to 50m with deco in OC air.
Beyond this there was military/technical training ("alto fondale" in Italian).
With the ARO this was meaning to NOT performing the counter-lung evacuation procedure, which ensures to start breathing pure oxygen. Instead, a "proper" amount of air had to be left inside the bag and your lungs. Depending on this amount, diving was "safe" only inside a depth range, say 10m to 30m.
A lot of people did die diving CC rebreathers with such uncontrolled gas mixtures, and this was one of the causes of their abandon.

 

[AfterDark]

According to Rebreather History: From Conception to the Modern Era (1680-2012) - DIVER magazine

"1969: Walter Stark introduces the ‘ElectroLung’ mixed gas rebreather for $2,500, subsequently bought by Beckman Instruments. Beckman shuts down division in 1970 after a number of fatalities."

Why does it matter that it used discrete transistors (and other electronic components) instead of the integrated transistors (and other electronic components) that are used in microchips?

It doesn't matter all. However, what I posted was based on nobody seeing the use of microchips 50 years ago in CCRs not transistors in 1998. A lot of other things we take for granted didn't even register as possible 50 years.

 

[Centrals]

I(open circuit) have dived with CCR divers on few occasions. Things I have noticed:
1. They need at least an hr to get ready before departure for the dive.
2. After waiting for an hr and they might turn up and said there is a problem and his/her dive is cancelled.
3. Post dive washing(sterilizing).
4. Excess luggage payment.
5. Most if not all the units have been modified.
6. Spare part is not readily available and major issue will be shipping it back to the manufacturer.
7. Not many operators that I have came across were CCR friendly.
8. There are few more......

I really cannot see many divers would like to spend extra effort, money and time on a rec sport.