There are no formal rules, the one I use for myself is that in order for it to be vintage (to me) it must have been made in or before 1975 OR be equipment of the design, method or as used in diving practice prior to 1975. Vintage diving methods must be as practiced on or before 1975. Some types of equipment like jacket BC, split fins etc are never vintage
So, any type of jacket BC does not fit even if it were made in 1974 because it is not of the method or practice of vintage diving--like Mr. DA said, it is not just age but other things as well. Prior to the early 70s there were no BCs and very few SPG or octapus type rigs--we dove with a tank, double hose regulator and masks and fins, some of us still dive that way. On the other hand, a new horsecollar BC, new reproduction UDT fins and such as that are vintage even though brand new because they are of the same type, dsign and style and method. I realize there is room for argument and some items can go both ways. To me a single hose regulator is vintage only when used without an octapus and with a J valve though some few SPGs are vintage such as the SeaVue. So, to me a 1966 Calypso single hose used with no LP inflator, no octapus and maybe a SPG is vintage.
I think we are coming to a time when there maybe need for another catagory. I call that catagory "Transitional". It was transitional between modern diving today and our current equipment and methods and the Vintage era. In this period, roughly 1974 to 1988. I choose 1988 because that is when computers began coming on to the scene and other electronic dive devices. So, roughly, from the advent of jacket BCs up to the use of computers is Transitional. There were many cool regulators, fins, back inflate BCs, consoles, timers that are Transitional as well the addition of all sorts of color to dive gear. In some respects and please don't take this to far--but--Hog and DIR are somewhat Transitional as they eschew the use of computers and use back inflate BC which came into wide spread use in those years. Yes, they were there--I have one. Probably putting way to much thought into all this but those are my catagories. Whether vintage or not, if you like it then dive it and have fun.
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