Submersible Pressure Gauge (SPG)

[John C. Ratliff]

Dale,

That diver has a Mk 13 Day/Night flare attached to his knife with masking tape. We did not use duct tape, as we needed to get the flare by breaking the tape, so masking tape worked to keep it is place. I guess it could be used as a shark repellant, but it was mainly for signaling during night jumps, or during day jumps where the conditions were pretty bad. It had an orange smoke for the day, and a bright light for night. I used one just once when we made a dive off an Okinawian flat-bottomed boat, and were swept away by the current in a search attempt for a helicopter that went down into the ocean in 1968. In ten minutes we were almost 1/4 mile away. They saw the smoke and came in to pick us up.

I've been trying to determine through my dive logs when I started using an SPG. I'll post more shortly. I have one photo from the mid-1970s which shows my equipment. I'm pretty sure I was using a SPG by this time. I participated in the Warm Mineral Springs Underwater Archaeological Project with Sonny Cockrell in about 1975. He required both the SPG and an octopus regulator for all divers, and I was a safety diver for the project that summer.

My first entry in a dive log was on June 25, 1973. It stated, "90. Used Dacor Dart reg.--when noticeably low on air (no sea view gauge) have 20 breaths." But I was recording "Air Used" since July 10, 1971. I may have been recording air pressure before and after the dive, however. On July 1, 1974 my log records, "...A pressure gauge is a must for planning these dives, and it should be planned like the astronauts plan EVAs (space "walks"), 'cause that's what we do when diving. The aqualung is not so much a tool as a life-support system for use in a cold & at least somewhat hostile water environment."

SeaRat

 

[danvolker]

"Commonly available" is the key question. I was certified in 1972, back when certification included many hours over several weeks, and I don't recall ever being told about SPGs. We were trained with J valve tanks. K valve tanks were mostly used with unbalanced regulators so moderate breathing restriction signaled low air. Modern SPGs don't seem to have been publicized in diving magazines until well into the 70s, and I never noticed one in any of the dive shops I frequented.

No one ever tried to sell me one, or even show me one, so I have to assume they were not commonly available, at least here in the North East, admittedly far from the epicenters of scuba activity. I bought the first SPG I saw, around 1974, a black face Scubapro in a chrome-plated case that read up to 3500 psi. I still have it and it still works fine, after several rebuilds.

Money was not an issue. I did see various gizmos that used protruding feeler gauges on the first stage, or were simply standard tank pressure gauges that were submersible but virtually unreadable by a submerged diver, but to me these were basically useless and do not constitute what I would consider a real SPG, certainly not a useful reliable SPG like the one I bought 40 years ago. Those items remind me of the late 60s Healthways Airflo regulators and their first stage tank attachment, a flawed somewhat bizarre method that seems in retrospect to have been a movement in the direction of modern DIN attachment.

The unanswered question remains. Why did so many divers remain unaware of SPGs until the early 70s? Is it because there were no really good ones until then? Was there a breakdown in marketing strategy? I know the cost was not a issue for me and for many other divers. We simply did not know they existed because our only sources of information-- magazines, dive shops, and other divers-- seem to also have been unaware of their existence.

I was also certified NAUI in 72, by Great Lakes divers in Buffalo, NY.
Even in 76, when I was diving in Tobago, almost no one had ever seen or used a spg..... And when I did see one, it was one of those--"why would I need that ?" kind of things, since it was so easy diving with the J valve....
A very large percentage of the spearfishing divers I knew back then ( most of my buddies), would always hunt to the last breath, pull the j valve, and then go for that one last fish...but now we would be ready for the air to run out, and for the free exhaling ascent to the surface....which was also incredibly easy. To listen to all the fear mongering today about slow ascents and safety stops, you would think that all of us back in the 70's would have been bent like pretzels with all the free ascending--but in fact, I never even heard of anyone that got DCS that was known to any of us.

We also had an adage back then...."anyone that needs a BC deserves to drown".... of course, you would say that with a smile on your face, and only half mean it l

 

[DaleC]

Ok John, now what is the thing between the tanks in pic #1 of your last post? I want to say something to hold lead?

Dan, how long would those spearo dives last usually? I can't speak to practices of the past but I find there is such an emphasis on pushing NDL's today among my peers, especially with bigger steel tanks. I usually dive a single 72 and don't worry much about ascents because it's pretty hard to get into too much trouble with one... well usually

 

[Bob DBF]

The unanswered question remains. Why did so many divers remain unaware of SPGs until the early 70s? Is it because there were no really good ones until then? Was there a breakdown in marketing strategy? I know the cost was not a issue for me and for many other divers. We simply did not know they existed because our only sources of information-- magazines, dive shops, and other divers-- seem to also have been unaware of their existence.

I think there were a number of factors in play. When I started I didn't even have a dive shop available, the gear came from Sears and I filled the tank a an industrial gas company, I didn't even run across another diver for almost a year, but I was a young kid in rural Massachusetts. I may have seen an ad for one but if it was as expensive as the one shown earlier, I would have dismissed it and forgot about it immediately. Heck, I had a tank checker, depth gauge, and watch, what else did I need?

Over the years I mostly dove solo, but the guys I dove with didn't have SPG's and we didn't need them so it was not an issue. I remember seeing one at a price I could afford in the late '70's, bought it and loved it. Got it before I bought a second second stage because I thought it was a more useful tool.

This was an era before big time marketing came to SCUBA and divers and dive shops alike were looking for good solid equipment that could stand the test of time and give value to the diver. It took more time for the cutting edge to become normal back then, and before people were trained to buy and upgrade to the newest gear available on the advise of ads and salesmen.



Bob
-----------------------------
I may be old, but I'm not dead yet.

 

[danvolker]

Ok John, now what is the thing between the tanks in pic #1 of your last post? I want to say something to hold lead?

Dan, how long would those spearo dives last usually? I can't speak to practices of the past but I find there is such an emphasis on pushing NDL's today among my peers, especially with bigger steel tanks. I usually dive a single 72 and don't worry much about ascents because it's pretty hard to get into too much trouble with one... well usually

These were back when we did 60 for 60.....
Capillary depth gauge and watch with rotating bezel.
There was NO Nitrox....so pushing 60 to 80 foot deep stuff with only air, did not make a larger tank make any sense....I had a bunch of steel 72's through into the late 90's.....one of my doubles rigs from early 90's was double 72's with me using independant regs for each ( though I was using pressure guages on each one for these 280 foot air dives...breath one down to 1500 psi from it's jacked 3000 psi start.....then go to the other......allowed 25 minute bottom times and hour long decos.....But I was not doing the 280 foot stuff in the 70's.....deepest then was 140 ( my first ocean dives

 

[John C. Ratliff]

Dale,

Those were double AL 72 cubic foot tanks at a working pressure of 2475 psig. They were the infamous "floaters" that required lead weights. This center PVC tube took 6 two-pound Mar-Vel Pak weights, and had a quick release at the bottom. With that configuration and weight, they worked well even though they were a bit long.

I have my old NAUI News publications, and will try to figure out when NAUI started talking about the SPG. I took my NAUI Instructor's course (NAUI #2710) in 1972 (SB 72), and do not remember a real emphasis on SPGs at that time. I did find a reference in NAUI NEWS January 1973 to pressure gauges being required, but it did not say "submersible..." This was in respons to a letter I wrote about requiring a life vest, and the long reply did not really specify whether the life vest was required.

By the way, another instructor named "Sam Miller (NAUI A-27) had a letter in the same issue of NAUI NEWS. His were comments on a previous article "Depth Limits," Sept/Oct 72 NAUI NEWS.

SeaRat

PS, David Richie Wilson gave us a link on the VSS website to a You Tube video of British divers in 1956, using double hose regulators with SPGs!
[video=youtube;dzljaFkWyrY]http://www.youtube.com/watch?v=dzljaFkWyrY[/video]

 

[captain]

Other reasons SPG weren't in common use was safety stops were not yet a normal procedure so there was no need to have enough air to do one and boats didn't have the back on with 500 PSI rule. I boarded the boat many times with under 100 PSI.

 

[danvolker]

Other reasons SPG weren't in common use was safety stops were not yet a normal procedure so there was no need to have enough air to do one and boats didn't have the back on with 500 PSI rule. I boarded the boat many times with under 100 PSI.

Exactly. The only real concern was pulling ALL the air out of the steel 72 on the ascent, and then potentially getting some saltwater into the tank...with the attendant rusting this could cause..

 

[Sam Miller III]

Fellows Lets get back on the Subject =="SUBMERSIBLE PRESSURE GAUGES"

If you like begin another thread on price comparison or your personal expereinces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The post was to demonstrate to those who loudly proclaim that "I began diving there was no SPG!" that there were SPGs --The American version was introduced in 1954 and the French (European) introduced in 1930s.


A question for RMBoulder, who has a good handle on published history and others who are internet savvy is:

"What was the design defect of the MarMac SPG that made it so dangerous ?"

I suspect inquiring minds will want to know ...

The Marmac had three design defects they were;
1.
2.
3.

Any guesses before Ryan swoops in with the answers???


SDM

 

[John C. Ratliff]

Fellows Lets get back on the Subject =="SUBMERSIBLE PRESSURE GAUGES"

If you like begin another thread on price comparison or your personal expereinces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The post was to demonstrate to those who loudly proclaim that "I began diving there was no SPG!" that there were SPGs --The American version was introduced in 1954 and the French (European) introduced in 1930s.


A question for RMBoulder, who has a good handle on published history and others who are internet savvy is:

"What was the design defect of the MarMac SPG that made it so dangerous ?"

I suspect inquiring minds will want to know ...

The Marmac had three design defects they were;
1.
2.
3.

Any guesses before Ryan swoops in with the answers???


SDM

Dr. Miller,

Here are my guesses:
I'm going to say that the SPG you are talking about had a problem when pressurized in that it was inflexible and hard to see. It probably also had no O-ring seal to allow it to be rotated so as to be readable.

SeaRat