hard hat (both the old and the new as in your avatar...both are hard, not necessarily heavy, right?)
True. The “old” hats were spun copper, and displaced a lot more water than they weighed. The weight varies but the US Navy Mark V is 54 Lbs for the hat and breast plate. The navy used an 85 Lb weight belt plus 35 Lb shoes, though the commercial diving industry’s models were around 15-25% lighter.
Modern lightweight hats are pretty close to neutral in the water and in the 20-30 Lb range. Most are fiberglass and a few are Bronze or Stainless. The industry leader is
Kirby Morgan. This is the same Bev Morgan who was an early pioneer in Scuba diving. With few exceptions they have demand regulators, support freeflow, and bailout bottles to backup the primary umbilical supply. Also hard-wire communications is standard.
Kirby Morgan actually started building heavy-gear/spun copper hats with dramatically improved large view ports made from 1" Plexiglas. They soon added fiberglass full face masks and starting building experimental mask/hat hybrids for the Navy. Fiberglass was one of Bev’s many talents picked up from building surf boards.
Those divers with the heavy duty metal helmets and lead boots. WWII Salvage diver.
"....the what?"…
I guess "....the what?" prompted my question. It was called “Deep Sea” or “Hard Hat” gear in the Sea Hunt Days (1950s). Heavy Gear became common in the US commercial diving industry after lightweight FFMs and hats started to dominate. I lost track of what the general population called it. Believe me, I wished it was WWII vintage. In hind sight I don’t regret training in this gear, but I am sure glad I never had to actually work in it.
As much as I hate to say it, being one of the many post-heavy gear evangelists, heavy gear still has its place. Aside from being the least expensive gear to maintain, it is what you want to wear in a cold contaminated harbor running a hack hammer. You can make yourself 50 Lbs heavy on the bottom or wrap your arms around some 200 Lb part, inflate the suit, and walk it over the bottom like you are superman… just don’t let go.