Karl Shreeves

An experienced technical, recreational and science diver, Karl Shreeves has been diving since 1970. He is an instructional designer for PADI, with broad experience that includes cave exploration, mapping and research (Cambrian Foundation), saturation human spaceflight study support (NEEMO), and dozens of underwater media production projects. A frequent participant and contributor at diving science events, he started diving CCRs in 1993 at the first Rebreather Forum, and is presently certified on several units.

How and why do you use checklists?

So there I was, all alone on a night dive, midwater underwater, empty BCD and an SPG pegged on 0. Luckily, I’d gotten a breath of zilch at 5 metres instead at 18 on the bottom below, so I kicked back up, orally inflated, exited and missed the dive – and that was good news. I’d skipped predive BWRAF and it could have killed me.

It’s easy to rationalize skipping checklists because most of the time, you don’t catch anything. In fact, something would be wrong if you did. But as my story shows, most doesn’t mean always. The biggest lie we tell ourselves is that we won’t make a mistake, but we’re human, right? Of course we will.

Since my no-air-midwater-alone-in-the-dark event in 1987, whether it’s BWRAF on a rec dive or more detailed written one for a tec dive, I always use a checklist. I’m not stupid (I don’t think, though some people seem to disagree) and I usually find everything in order, but it’s paid off many times – closed valves, trapped hoses, dead battery computers, you name it – here are just three more notable ones off top of my head:

  • After setting up for an OC gas dive to 65 metres, running my checklist found none of my inflation systems connected (OC tec you’re often very negatively buoyant at dive start, if you didn’t know).
  • Prejump CCR check found an oxygen sensor that was working just fine after initial set up now off kilter presplash an hour later (yes, this one delayed the dive, but considerably less than aborting it after 5 minutes, or worse, things snowballing into hypo/hypoxic gas, bailing out or worse).
  • Test breathing my alternate second during a no stop dive check revealed the adjustment access plug missing (a problem that can continue unnoticed for many dives if you’re not checking it) meaning you’d suck water if you tried to breathe from it. Easily fixed – and what do you know, on that exact dive I had to use it because my primary second stage mouthpiece tore. (Yes, I’d have managed, but glad I didn’t have to — but more importantly I shudder to think what would have happened if I’d given it to an out-of-air diver.)

Experience is the best teacher, and experience using checklists and not using checklists has taught me this: Use checklists because while they are deceptively simple, they work. Even better than learning from experience is learning from someone else’s experience – learn from mine. Use an appropriate checklist, with your teammates, before every dive – I promise that eventually you’ll be glad – maybe very glad – you did.