Not ever having owned one, are there any kinds of certifications on the commercially produced ones?
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I am a certified diver. I have 2 full SCUBA rigs but none onboard at this time. (in the store room)
When I bought my Brownie Third Lung, I told the owner that I was certified.
His reaction was a bit disappointing. Certification/classes are not required to buy one. Sort of like buying a gun, "Here you are, have fun.", instead of,"we offer a lesson on how to use it, safely."
With a hose type dive rig, it should take a couple of hours of instruction.
For now, I have 4 tanks onboard, securely stowed on the upper deck and first and second stage hose rig.
Diving is not for everyone. If you are afraid or uncomfortable diving, dont buy or build a rig. Sadly, I dont think there are any "try before you buy" classes.
I will tell you, dragging that daymned hose behind you can really really get to be old.
My recommendation it to remain tethered to the boat. If you are out in the area where you cannot anchor and the boat drifts off, whatcha gonna do?