Found a 1980s dive manual at a thrift store with helium tables that looked nothing like what we use now

Picked it up for three bucks out of curiosity and the decompression stops are way shorter than anything I'd trust today. The book even had a section on using pure oxygen at 50 feet which I'm pretty sure would get you fired now. Any old timers here actually dive with those old schedules?

2 comments

2 Comments

bell.taylor1mo ago

Flip through to the section on gas switching, bet it says something wild about just yanking your regulator out and grabbing a new bottle mid water. Those old tables assumed you could bounce between mixes without any transit time, which is nuts. Pure oxygen at 50 feet was basically a seizure waiting to happen, but they thought CNS toxicity was a Navy problem, not a rec diver thing. The lack of any deep stops in there tells me they had way less fear of bubble formation back then, or just didn't know better.

karent751mo ago

And yeah, I've had to talk a buddy out of trying that exact kind of switch on a deep air dive because he read some old manual and thought it was fine. The reality is your body needs time to adjust between mixes, even if the table says you can do it instantly, and skipping that transit is how you end up with a narcosis headache or worse. Honestly, I just plan a slow ascent with a proper hang at 20 feet now, keeps the bubbles quiet and my brain from getting too spicy.