Incident—all well

[SlugLife]

Diving in the Keys. My Buddy and I were in the water at 25ft swimming around the reef near the boat, waiting for the other divers to enter the water. I typically dive with steel tanks. Just as everyone was down and the guide started out, I heard a loud roar. I bumped my Buddy, and pointed to my tank. She immediately gave the thumbs up—and shoved her octo towards me, but I was still getting nitrox so I didn’t take it. She grabbed the first stage of my tank and started pulling me up—and we went up together slowly. As we were going up I started to unbuckle from my BCD in case the steel tank became too heavy—I was going to ditch my gear if necessary and swim to the surface. At the surface she turned off my tank. I swam to the boat, connected up with my second tank while everyone patiently waited at depth, and once back in we had a nice dive. Turns out my O-ring had blown.

Thoughts afterwards:
1. I was happy we were not at 100ft but only 25ft
2. Instead of ditching my gear (which I did not) I could have inflated my BCD before my tank emptied or orally inflated my BCD and ditched my weights.
3. Was proud of my Buddy for her quick action. Neither of us panicked despite all the bubbles and noise…but again, at 25ft the surface is right there.
4. I will inspect my O-rings closer prior to future dives
5. I was happy that the dive op accommodated me and allowed me to switch out quickly and take the dive.

Which o-ring blew?

1. I had a similar story. Lots of bubbles in my face. I started looking for my octo, but then decided it was easier to just surface. On the surface, I discovered the regulator-hose had come loose from my 2nd stage.
2. Agreed. Hindsight is 20/20. Ditching your gear may have been one effective way to not-die-in-case-of-emergency. To that end, an imperfect solution is better than none. The fact that you made a decision, even if imperfect, is a good thing.
3. Good buddy!
4. I'd be curious which o-ring blew. That said, I've gotten into servicing my own gear, and it's probably a good idea to replace o-rings once-per year, at least the ones you can access easily.

edit: You may be over-weighted. Try to adjust your weighting, such that at the end of your dive, you're neutral with an empty BCD at 15ft and 500 psi. Broadly speaking, if you dial in your weighting, you should be able to surface from depth with an empty BCD without excessive amounts of effort. The sidemounting.com instructor shows this with two tanks, and I've done it myself for practice.

 

[chillyinCanada]

Exactly…back inflate wants to face plant me. Not about sinking straight down.

Lay back and relax, instead of fighting the bcd. If it continues to push you forward, let a bit of air out.

 

[SlugLife]

Exactly…back inflate wants to face plant me. Not about sinking straight down.

If you ever have a long swim or wait, and a back-inflate that wants to face-plant you, (aside from deflating your BCD slightly) you can use a SMB or DSMB like a "pool noodle." I've done that on more than a few occasions.

 

[wetb4igetinthewater]

This reminds me of my first night dive on vacation (when I was a recent AOW diver) at Playa Del Carmen. It was a bit of a rush to get onto the boat offshore. We couldn't see too much setting up. My then girlfriend dive buddy told me under the surface that there was a stream of bubbles between the first stage (Yoke) and the valve. This increased in rate, so our dive was a little bit short, but not too short. Shortly after surfacing, the o-ring blew. Glad I wasn't underwater when that happened.

Feathering the valve on a single backmount tank?

Sure, why not? At least you avoid losing gas while you exhale.

 

[Marie13]

Sure, why not? At least you avoid losing gas while you exhale.

Given how low I see many recreational divers wear their tanks, I bet reaching the valve might be an issue. Tanks are often below their butt.

 

[wetb4igetinthewater]

Given how low I see many recreational divers wear their tanks, I bet reaching the valve might be an issue. Tanks are often below their butt.

Why? When the valve is down by your arse, it is easy to reach.

 

[lermontov]

Diving in the Keys. My Buddy and I were in the water at 25ft swimming around the reef near the boat, waiting for the other divers to enter the water. I typically dive with steel tanks. Just as everyone was down and the guide started out, I heard a loud roar. I bumped my Buddy, and pointed to my tank. She immediately gave the thumbs up—and shoved her octo towards me, but I was still getting nitrox so I didn’t take it. She grabbed the first stage of my tank and started pulling me up—and we went up together slowly. As we were going up I started to unbuckle from my BCD in case the steel tank became too heavy—I was going to ditch my gear if necessary and swim to the surface. At the surface she turned off my tank. I swam to the boat, connected up with my second tank while everyone patiently waited at depth, and once back in we had a nice dive. Turns out my O-ring had blown.

Thoughts afterwards:
1. I was happy we were not at 100ft but only 25ft
2. Instead of ditching my gear (which I did not) I could have inflated my BCD before my tank emptied or orally inflated my BCD and ditched my weights.
3. Was proud of my Buddy for her quick action. Neither of us panicked despite all the bubbles and noise…but again, at 25ft the surface is right there.
4. I will inspect my O-rings closer prior to future dives
5. I was happy that the dive op accommodated me and allowed me to switch out quickly and take the dive.

sounds like you and your buddy did well in the situation -improvising and/or making split second decisions -its alway easy on the keyboard to disect what else you could have done so I suggest you take a day out with a competent buddy and go over all the various options people are suggesting and trial them in a shallow and safe spot to see what does and doesnt work

My buddy and a I regularly go out to a nearby lake and practice all sorts of emergency scenarios and have a a list of drill exercises we randomly practice

 

[rongoodman]

I don't get it. The tank is getting lighter as it loses gas, not heavier, and the BC is providing more flotation as you rise, not less, so why would you think you needed to ditch your rig or need assistence from your buddy to reach the surface?

 

[Belzelbub]

One of the reasons I use DIN. I have witnessed several such o'ring extrusions on INT/Yoke valves. Luckily, all of them occurred on the surface or only a couple of meters below surface.

Exactly. I haven’t had any blowouts, but plenty of leaks with yokes. Only problem I had with a DIN was an o-ring that went missing. That’s easily spotted by turning the tank on.

Hmmm. Seems to me that your configuration is too negatively buoyant. I recommend taking the time to do a weight/buoyancy check. (Things change if, for example, you have lost body weight or switched to a thinner wetsuit.)

Agreed. A tank actively dumping gas should not be a buoyancy concern. It’s not going to get less buoyant that’s for sure, and if staying at the surface with a nearly empty tank is a problem, that sounds like too much weight.

Exactly…back inflate wants to face plant me. Not about sinking straight down.

As does this. Overfilling a back inflate can lead to the face plant issue. Less ballast means less gas required to stay buoyant, so you’ll be unlikely to tip forward. Trim weight behind the bladder helps as well.

 

[johndiver999]

I don't get it. The tank is getting lighter as it loses gas, not heavier, and the BC is providing more flotation as you rise, not less, so why would you think you needed to ditch your rig or need assistence from your buddy to reach the surface?

As I mentioned, I think the idea stems from a significant amount of insecurity or lack of confidence in the buoyancy and weighting of the rig.

Sorta like, you loose power in your pick up on the freeway, so you unbuckle the seat belt and start to crawl out the window at 50 mph because you think the truck may explode in flames.

I am curious to hear the list of potential problems or failures that might arise on a shallow dive being conducted by a novice, for which people think turning off the single back mounted tank is a good idea?