This subject again…
Here are a few interesting points:
Dacor had double hose regulators well all the way into 79 (I am not sure if that was the last year). Actually one ironic observation is to see the Dacor DH on the same catalog page as their octopus (which the DH could not accommodate).
Other manufacturers that continue to build DH into late 70 and beyond: Nemrod and Spirotechnique. Actually it is possible that the only manufacturer that discontinued making DH and was still in business in the late 70’s might have been USD. Most of the other manufacturers of DH regulators were just out of business or going out of business: Healthways, Sportways, Voit, and many of the Europeans.
So the truth is that a lot is being based on only one manufacturer of DH regulator. It is for sure the most used and IMO the most important of the manufacturers of DH regulators, but I find it funny that many of these discussions tend to forget about the rest of the DH regulators (and the rest of the world).
I know the SPG was around in the 50’s, but I am not sure when it became very popular. I do know that by 1971 it was the standard in the Caribbean (and we were normally behind the times). By the time I started working at DSC in Puerto Rico, no one gave it any thought about diving without an SPG. My buddy and I were the only ones (that I am aware of) that would occasionally dive without an SPG in order to dive our Royal Aqua Master.
Yes, the inflator and octopus didn’t become popular until mid to late 70’s (the inflator became popular before the octopus), but the alternate air source on a pony bottle was actually very popular among wreck diver on the north east in the mid 60’s. Pallets of oxygen bottles were being sold and marketed as pony bottles by a number of dive shops in the NE at the time (the term “pony bottle” was probably not in existence at the time).
Flotation devices are another interesting subject. The discrepancy between the time period of there existence and there popularity make it even more confusing to accept when they were around.
Mae West and other flotation devices were around since the 50’s
The Fenzy was around since 1961 (in the US since about 1968).
Scubapro BC jacket 1971.
Also power inflator 1971.
Watergill At Pack wing BC (with weight integrated, inflator, etc) 1972
I believe that Watergill also had an instrument console around 1972.
Just a few facts (or at least as factual as can easily find) to muddy up the subject.