Runaway Ascent (Analysis/Lesson Learned)

[Togalive]

First off, thank-you to everyone for the well thought out and thought provoking replies, they have all made me think even more about what happened, why it happened, how it was handled, and how it could have been prevented. Also, I realize now that my being able to hover on our dives without air in my BC is not something I should expect to be able to do once reaching greater depths due to compression, at which point I don't think buoyancy via breath control wouldnt be enough. As per the helicopter analogy, that is a great way of thinking about it! To answer your question Erku, currently when diving I'm keeping a pretty horizontal profile whether im finning or in a stationary position (much more so with the new back inflate BC). Usually if I want to move up, I just breathe in a bit more than a usual breath, and once I've gone up the amount I want, I just keep breathing normally, and vice versa for descending a bit. If its say 10+ ft up or down, id repeat either of thr two one or two additional times. But based on some replies, it looks like I shouldn't expect to be able to do this when diving deeper with no air in my BC lke I am currently.

As far as all the suggestions for my father, I was going to simply reiterate what some of you suggested to him, but I've opted instead for him to hopefully read a printout of the replies, so any element of a son suggesting things to his father will be absent. I'm confident that once he reads it, it will help settle any questions he might have himself about what happened and how we mayh both improve our diving experiences.

Thankyou again!
Toga

P.S: Bubble, thankyou for you well developed reply! It answered all of my questions and gave me a better understanding of just what happened, and what needs to be done to prevent future incidents, thankyou!

 

[Bubbletrubble]

It would be remiss of me not to mention that there are some divers out there (you know who you are!) who dive without a BCD. These people use lung volume to compensate for changes in buoyancy throughout the dive. Something to contemplate is how much buoyancy swing these people are compensating for with their lungs -- tank buoyancy swing + compression/expansion of neoprene. To this end, they weight themselves differently from the method that I described and the method that your instructor taught you. It sounds like a fun thing to try sometime with the proper mentoring. I only mention this as a special case in diving, but it does exist. As I learned in high school anatomy class...there's more than one way to skin a cat.

For what it's worth, it sounds like your buoyancy control is quite good. Sure, you can use breath control to mitigate buoyancy changes. Lots of divers use the method you describe for going over objects, e.g., a mass of coral, and then returning to the same depth. Heck, what's the point of fiddling with the power inflater if the depth change isn't great and you're going to return to the original depth anyway, right?

Enjoy Bonaire!

 

[dumpsterDiver]

The father should learn that the fastest way to correct excess bouyancy is to SCREAM "sheet!" Serously, if the diver begins to feel too bouyant, the first thing to do is to exhale completely. It is very fast and very simple. If after the exhalation the diver is rising, then they need to dump a little air, if not then they can inhale a little and see how it feels. If he learns this trick, he will probably stop the yo-yo diving.

Also he is almost certainly over-weighted as everyone said.

Also, a certified diver needs to be able to dive without a power inflator hooked up and rely only on oral inflation, in case an inflator starts to bleed air (a very, very common scuba failure). If dad practices bouyancy control with the right amount of lead, without the power inflator hooked up, he will probably pick this up pretty quick. He needs to learn this in a very controlled environment. Once he realizes that he does not need to mess with the BC if he is not changing depth and gains the skill and confidence to dive without a power inflator, he will be much better off.

 

[Togalive]

It would be remiss of me not to mention that there are some divers out there (you know who you are!) who dive without a BCD. These people use lung volume to compensate for changes in buoyancy throughout the dive. Something to contemplate is how much buoyancy swing these people are compensating for with their lungs -- tank buoyancy swing + compression/expansion of neoprene. To this end, they weight themselves differently from the method that I described and the method that your instructor taught you. It sounds like a fun thing to try sometime with the proper mentoring. I only mention this as a special case in diving, but it does exist. As I learned in high school anatomy class...there's more than one way to skin a cat.

For what it's worth, it sounds like your buoyancy control is quite good. Sure, you can use breath control to mitigate buoyancy changes. Lots of divers use the method you describe for going over objects, e.g., a mass of coral, and then returning to the same depth. Heck, what's the point of fiddling with the power inflater if the depth change isn't great and you're going to return to the original depth anyway, right?

Enjoy Bonaire!

Thankyou for mentioning that! While I have no intentions of diving without a BC anytime soon, I find the fact that some people dive like that quite interesting in relation to, in retrospect, how I am currently diving. As for what you said at the end of your post, thats exactly what goes through my mind when thinking of how im going to go over some of the large boulders around where we dive

The father should learn that the fastest way to correct excess bouyancy is to SCREAM "sheet!" Serously, if the diver begins to feel too bouyant, the first thing to do is to exhale completely. It is very fast and very simple. If after the exhalation the diver is rising, then they need to dump a little air, if not then they can inhale a little and see how it feels. If he learns this trick, he will probably stop the yo-yo diving.

Also he is almost certainly over-weighted as everyone said.

Also, a certified diver needs to be able to dive without a power inflator hooked up and rely only on oral inflation, in case an inflator starts to bleed air (a very, very common scuba failure). If dad practices bouyancy control with the right amount of lead, without the power inflator hooked up, he will probably pick this up pretty quick. He needs to learn this in a very controlled environment. Once he realizes that he does not need to mess with the BC if he is not changing depth and gains the skill and confidence to dive without a power inflator, he will be much better off.

I've spoken with my father tonight and we are going to make a considerable effort to make sure he is properly weighted before we get into any diving around Bonaire, as for me, I've made numerous notes with my last weight configuration and placed them everywhere just so I cant forget (will have to adjust a bit for salt water in Bonaire though). Your initial suggestion is one which I'm going to bring to his attention before we dive as well, as a kind of "In case you start shooting up again, do this". Besides the weighting issues, I'm confident that the other issues will improve as his breath control does once were in Bonaire and able to see more than 10 ft

Once again, ScubaBoard has proven to supply some excellent replies, which my father has greatly appreciated as have I!

 

[Bubbletrubble]

I've spoken with my father tonight and we are going to make a considerable effort to make sure he is properly weighted before we get into any diving around Bonaire, as for me, I've made numerous notes with my last weight configuration and placed them everywhere just so I cant forget (will have to adjust a bit for salt water in Bonaire though). Your initial suggestion is one which I'm going to bring to his attention before we dive as well, as a kind of "In case you start shooting up again, do this". Besides the weighting issues, I'm confident that the other issues will improve as his breath control does once were in Bonaire and able to see more than 10 ft

It's great that you're keeping track of your weighting needs in various gear configurations.
What kind of exposure protection will you be using in Bonaire?
What kind of exposure protection have you been using on local dives?
Do you know whether the tanks you'll be using in Bonaire will be the same as the ones you use at home?
Do you see where I'm going with this line of questioning?

 

[Togalive]

It's great that you're keeping track of your weighting needs in various gear configurations.
What kind of exposure protection will you be using in Bonaire?
What kind of exposure protection have you been using on local dives?
Do you know whether the tanks you'll be using in Bonaire will be the same as the ones you use at home?
Do you see where I'm going with this line of questioning?

On Bonaire we're both bringing our 3 Mil suits, which we use to snorkel at our local diving area. Usually when diving in the same area though, we both wear 7 mil suits because the thermocline usually is pretty varied. The most I've seen it swing was from 82 on the surface to 64 at about 25 feet and below. One thought I had was whether I might actually end up removing weight on Bonaire considering how thin my suit will be compared to normal diving conditions here, but then again were diving fresh water here too.
I'm pretty sure we'll be using AL80's, so they should be the same. We've considered getting Nitrox certified for the trip, but have opted against complicating things any further, air is perfectly good enough for our lungs for the time being haha

 

[ZenDiver.3D]

Togalive, I have something else to add. Sometimes with new students, I find one who just keeps needing more weight, until he Must be a giant rock, but still can't descend. These folks are holding air. They are breathing with their diaphram expanded all the time. They are not relaxed and this xan happen. Thus they need more weight, and have trouble with buoyancy at depth. Try working on breathing techniques above water too.

In the pool, I establish weighting for my students like this.
In the shallow end, we have no weight in their bc's. We make absolutely sure all air is out of the bc. Then we lay face down on the water and breathe. We try to focus our breathing and see if we can sink at all. Then we spend about 5 minutes breathing and practicing any sink and rise we can without weight. Then we add 1 kilo to each side and do it all again. Most can sink and stay down and rise in a controlled manner by then. Some need an extra kilo divided between sides. Then we go to the standing neck deep area and see if we can sink and use our breathing to rise and fall a bit. At that point, we stand up and discuss the inflator hose. How it is used 1- 3 SMALL pftts to establish neutral buoyancy, and that is All.
Then I have them make laps holding one finger straight down so they can just touch the bottom. They must use their breath to keep from going up or down.
After all that, we use the lines on the wall of the pool to touch with our finger for reference. They must rise up and then across and back down without touching the inflator hose. All breath control. This drill really helps. Give it all a try before your trip. It is worth it.

Then in salt water, start with your pool or fresh water weight and add 1 kilo to each side and do a buoyancy check. Don't let the dm's overweight you or him there. Be able to determine your own. Let us know how these things help.

 

[Bubbletrubble]

OK, the tanks will be the same, but the wetsuits will be different. It doesn't sound to me like you know your weighting requirements while wearing the 3mm suit.

Freshwater to saltwater weighting conversion is to add roughly 2.5% of the entire weight of you + all of your gear. For an average-sized person, that turns out to be an additional 5 or 6 additional pounds, provided that all of your gear is the same.

Taken together, this means that you need to do a weight check when you get to Bonaire. Review your OW manual on how to do this. A "check-out" dive is generally part of the orientation for first-time dive tourists there. Do your weight check at the same time.

 

[Togalive]

OK, the tanks will be the same, but the wetsuits will be different. It doesn't sound to me like you know your weighting requirements while wearing the 3mm suit.

Freshwater to saltwater weighting conversion is to add roughly 2.5% of the entire weight of you + all of your gear. For an average-sized person, that turns out to be an additional 5 or 6 additional pounds, provided that all of your gear is the same.

Taken together, this means that you need to do a weight check when you get to Bonaire. Review your OW manual on how to do this. A "check-out" dive is generally part of the orientation for first-time dive tourists there. Do your weight check at the same time.

You are correct, we have never dived in our 3 mils (I've done some freediving in mine, but generally its just too cold around here to stay at a sustained depth with them), in fact we purchased them exclusively for the Bonaire trip since we got them at a very good price from the LDS. Gotcha on the weighting, your knowledge on the subject is well appreciated and a weight check is the first thing we'll be doing during our checkout dive once on site

Thanks again for all the info!

 

[scobyroo]

This is a great thread. I was browsing around and reading about buoyancy, and this was full of great advice. Being a noob, I'll definitely keep it on my radar.