Doing a more thorough Pre-Dive Check

[lowwall]

When I wrote my course on advanced dive planning, I had a whole section on these kinds of checks, and I based a lot of it on research I did years before working with assessment guides. There is a significant diminished return on a tool or process that is too long or too complicated--the whole thing goes unused.

A lot of this has already been worked out in aviation. They size the checklist to the time and attention available. Where appropriate, they will split a long checklist into two or more. Regardless of the number of checklists, the final list should be very short and just contain critical items.

For example my final check, just before entering the water, is only 3 items:
- deep breath off regulator while looking at SPG to make sure no one has turned off my air
- verify computer is on and O2% correct
- buddy is visible or in known location

 

[yle]

It seems that even for meticulous people, the BCD operation gets little attention in the pre-dive checks. My BCD process:

-- Well before the dive, fully inflate BCD, make sure overpressure valve opens properly
-- Make sure overpressure valve closes properly
-- BCD now fully inflated and holding air, test all dump valves by releasing a small amount of air
-- Confirm dump valves close properly
-- BCD now partially inflated, leave tank valve on

I leave the tank valve on and BCD partially inflated for a couple reasons. One is that the BCD is ready to hit the water in this state. The other is that when I check it later, maybe 10 minutes or so, I can tell if the BCD is "self inflating", i.e. a leak in the inflator. While both are rare, it's been my limited experience that a leaking inflator and dump valves that don't close properly are the two most common BCD problems (i.e. self-inflating or self-dumping.)

 

[MrChen]

It seems that even for meticulous people, the BCD operation gets little attention in the pre-dive checks. My BCD process:

-- Well before the dive, fully inflate BCD, make sure overpressure valve opens properly
-- Make sure overpressure valve closes properly
-- BCD now fully inflated and holding air, test all dump valves by releasing a small amount of air
-- Confirm dump valves close properly
-- BCD now partially inflated, leave tank valve on

I leave the tank valve on and BCD partially inflated for a couple reasons. One is that the BCD is ready to hit the water in this state. The other is that when I check it later, maybe 10 minutes or so, I can tell if the BCD is "self inflating", i.e. a leak in the inflator. While both are rare, it's been my limited experience that a leaking inflator and dump valves that don't close properly are the two most common BCD problems (i.e. self-inflating or self-dumping.)

Have you ever experienced a failure of the over pressure valve? If so, what was the experience and how did you deal with it?

 

[Ulfhedinn]

I do this before each dive... I either touch or examine each item.

Mask/HOOD
All Valves Open
Breath Both Regulators
Drysuit inflator/Exhaust
Wing inflation/Exhaust
Arms Out: Depth Timer/Computer -> Right
Arms Out: Compass -> Left
Backup Lights
Primary Light
Buckle
Crotch Strap
Cutting Device
SPG
Pocket Contents: (SHTF) Mask & Wetnotes -> Right
Pocket Contents: (Working) SMB & Spool -> Left
Fins
Modified S

 

[Wibble]

Have you ever experienced a failure of the over pressure valve? If so, what was the experience and how did you deal with it?

The dump valve fell off on the surface after fully inflating the BCD.

Was lower in the water and I noticed bubbles from he left hand side when inflating, reached down and no dump, just a hole! So inflated the drysuit for the surface swim to shore and kept more upright. Could have inflated a SMB and sat on it if needed.

 

[Fastmarc]

On a conventional BCD, I usually just tug the dump hose to dump air from the dump valve instead of raising the hose and one dive I tugged and it just came off. Luckily it was a shore dive with a slopping bottom, so not stress and I even continued the dive.
Always fully inflate the BCD until it purges and inspect those dump valves since that.

 

[peeweediver]

Added to the inflate/deflate BCD, make sure the inflate button is on correctly. A story on that: In Palau last December, my wife noticed the inflator button on her SS1 seemed loose right before splash in. No big deal, she thought. During the dive with the strongest current, while hooked in, things got interesting. When she went to deflate before unhooking, she noticed the inflator button was gone. She unhooked and started straight to the surface. The DM grabbed her while she dumped with her back valve and covered the opening where the button was thinking she should prevent the flow of sea water into the inflator. I thought by holding her hand on that spot she was inflating and her BCD was, in fact, inflating. We then had a marital spat about whether she should move her hand off that spot while she struggled to keep dumping from the back. Luckily, we came to a buoy line and she held on and we surfaced together. What did we both do wrong? When something isn't quite right, get it fixed before going in...especially when the guy who serviced the BCD is with you on the trip. Second, don't get into a marital spat underwater so that you forget that simply detaching the inflator hose was the right thing to do at that time. Interesting side note, another couple with us on the hook-in noticed a bump head parrot fish suck up something yellow, swim for 15 yards then spit it out. They laughed but didn't realize it was my wife's inflator button. With help from the crew, we were able to swap out everything from extra gear they had on board and continued to dive.
Oh well, we learned a few things.

 

[yle]

Have you ever experienced a failure of the over pressure valve? If so, what was the experience and how did you deal with it?

I've not experienced a failure of the valve, in the sense that it refused to open. But I encourage people (including my students) to inflate the BCD to check the OP valve mostly to ensure that the valve is opening properly and that it closes properly. As others have replied here, it's also a good time to check that the dump valves are screwed on tight.

Doing a lot of beach diving, I've found the two most common problems with dump valves are they loosen slightly or they get a tiny bit of sand in them, which prevents them from closing. Both problems are easy to fix... but much better to fix before entering the water.

 

[yle]

A lot of this has already been worked out in aviation. They size the checklist to the time and attention available. Where appropriate, they will split a long checklist into two or more. Regardless of the number of checklists, the final list should be very short and just contain critical items.

For example my final check, just before entering the water, is only 3 items:
- deep breath off regulator while looking at SPG to make sure no one has turned off my air
- verify computer is on and O2% correct
- buddy is visible or in known location

Oh my goodness... yes. This is how it should be developed and presented in basic OW training. Instead of just "check these things before a dive", which doesn't address when before a dive (many newish divers are caught off guard on a dive boat, because the moments prior to a dive can get a little chaotic... so the checklist gets skipped), a series of short checklists -- before leaving the dock, 20 minutes prior to the dive, immediately before entering the water -- would likely improve participation in pre-dive checks significantly.

 

[Searcaigh]

Check pee valve is connected and functional when wearing a drysuit.