Feet first ascent

[cdolphin]

I posted this in the Accidents and Incidents in reply to a story about a woman who was rescued in Edmonds WA after she somehow became inverted and needed help. I thought maybe I'd post it as a "Lesson Learned" too.

As an example of what could happen, and hopefully someone can learn from my ignorance......

My first dive in my new gear was also my first dive in an AOW class which for some unknown reason was also the Deep Dive in that class....apparently it isn't supposed to be the first dive in AOW.

That said, it was my first COLD water dive in Puget Sound with a back-inflate BC (with a 5mm shortie over a 7mm semi-dry wetsuit; lots of neoprene, which just adds to the buoyancy issues.) In my case a semi head-down attitude at some point during the dive caused air to get trapped in the lower part of the BC bladder and unbeknownst to me, I didn't have all of the air vented out. As I returned from depth with a lower-on-air tank, that air trapped in the lower portion of the bladder caused me to "stand on my head" and was causing an ascent. I tried to use the inflator hose to dump air, but it wouldn't vent, since I was feet-up. I didn't know enough to simply reorient myself to head-up and completely vertical: but I was trying to swim downward to stop the ascent, so I wouldn't have done that anyway. I remember thinking I was going to bounce to the surface feet first. Not a good plan after a deep dive. I had no idea what was going on. Not until after the dive was I told that the Instructor came behind me and vented some (or all) of the air using the bottom dump valve. I was so new (and, admittedly dumb - I should have become more familiar with the gear first) I didn't even know there was a bottom dump valve. But that air-dump still wasn't enough to keep my feet down. To stay down, I had to kick down for the rest of the ascent, which thankfully was a shore dive/gradual ascent.

An empty BC and more weight in general didn't cure the problem for subsequent dives. I started adding ankle weights and they keep my feet down, but I still haven't figured out how to solve the problem in any other way. I don't have this problem in warm water with this gear - so I keep coming back to the wetsuit, but I don't know any other possible causes or solutions.

 

[MXGratefulDiver]

I posted this in the Accidents and Incidents in reply to a story about a woman who was rescued in Edmonds WA after she somehow became inverted and needed help. I thought maybe I'd post it as a "Lesson Learned" too.

As an example of what could happen, and hopefully someone can learn from my ignorance......

My first dive in my new gear was also my first dive in an AOW class which for some unknown reason was also the Deep Dive in that class....apparently it isn't supposed to be the first dive in AOW.

That said, it was my first COLD water dive in Puget Sound with a back-inflate BC (with a 5mm shortie over a 7mm semi-dry wetsuit; lots of neoprene, which just adds to the buoyancy issues.) In my case a semi head-down attitude at some point during the dive caused air to get trapped in the lower part of the BC bladder and unbeknownst to me, I didn't have all of the air vented out. As I returned from depth with a lower-on-air tank, that air trapped in the lower portion of the bladder caused me to "stand on my head" and was threatening to cause an ascent. I tried to use the inflator hose to dump air, but it wouldn't vent, since I was feet-up. I didn't know enough to simply reorient myself to head-up and completely vertical: but I was trying to swim downward to stop the ascent, so I wouldn't have done that anyway. I remember thinking I was going to bounce to the surface feet first. Not a good plan after a deep dive. I had no idea what was going on. Not until after the dive was I told that the Instructor came behind me and vented some (or all) of the air using the bottom dump valve. I was so new (and, admittedly dumb - I should have become more familiar with the gear first) I didn't even know there was a bottom dump valve. But that air-dump still wasn't enough to keep my feet down. To stay down, I had to kick down for the rest of the ascent, which thankfully was a shore dive/gradual ascent.

An empty BC and more weight in general didn't cure the problem for subsequent dives. I started adding ankle weights and they keep my feet down, but I still haven't figured out how to solve the problem in any other way. I don't have this problem in warm water with this gear - so I keep coming back to the wetsuit, but I don't know any other possible causes or solutions.

What you experienced isn't uncommon among new divers struggling with unfamiliar gear. The solution is to get out and do more dives ... using the same gear all the time (a big advantage to owning your own gear). I would recommend doing those dives relatively shallow, and in fairly benign conditions (no current, reasonable vis, etc). Over the course of a few dives, your body will make the subtle adjustments needed to orient yourself in the way you desire ... and you will discover that those ankle weights are no longer needed.

Although there are rare cases where they are truly needed, I am not a big fan of ankle weights ... they are more often than not simply used to mask a skill deficiency. I tend to view them as "training wheels" for new divers who, in most cases, will either end up using them as trim weights elsewhere on their rig, or ditching them altogether after a dozen or so dives.

Doing a deep dive as your first cold-water dive, and using unfamiliar gear, is not a prudent decision. I am surprised your instructor did that ... for the very reason you described in your post.

... Bob (Grateful Diver)

 

[Bubbletrubble]

I have no idea why an instructor would ever do the deep dive as AOW Dive #1...especially without first evaluating the skills of the students in the class (not sure if your instructor did this).

Did you ask your AOW instructor for some help with trimming out properly?
At 50+ dives, you're at the right experience level to be conquering this issue.

Have you tried doing a shorter dive in the 7mm semi-dry alone (without the shorty)? Just curious whether all that neoprene is making buoyancy control and trim more difficult.

Another thing to consider is that AL80 tanks can get "butt-light" as they are emptied. It's no excuse for an uncontrolled feet-first ascent, though.

An instructor here on SB (ae3753) has posted several wonderful essays that you might find interesting:

• Horizontal Trim 101 - Uses
• Horizontal Trim 101 - Levers
• Scuba 101 - Controlled Ascents

You should come away from that reading understanding that several variables can be changed in order to achieve good horizontal trim.

FWIW, at one time I used a very poorly designed rear-inflate BCD that trapped air in a very annoying way...and I knew where all of the dump valves were and how to operate them. I got rid of that BCD very quickly.

Hope this info helps...

 

[cdolphin]

What you experienced isn't uncommon among new divers struggling with unfamiliar gear. The solution is to get out and do more dives ... using the same gear all the time (a big advantage to owning your own gear). I would recommend doing those dives relatively shallow, and in fairly benign conditions (no current, reasonable vis, etc). Over the course of a few dives, your body will make the subtle adjustments needed to orient yourself in the way you desire ... and you will discover that those ankle weights are no longer needed.

Although there are rare cases where they are truly needed, I am not a big fan of ankle weights ... they are more often than not simply used to mask a skill deficiency. I tend to view them as "training wheels" for new divers who, in most cases, will either end up using them as trim weights elsewhere on their rig, or ditching them altogether after a dozen or so dives.

Doing a deep dive as your first cold-water dive, and using unfamiliar gear, is not a prudent decision. I am surprised your instructor did that ... for the very reason you described in your post.

... Bob (Grateful Diver)

Thanks, Bob. It was a day of comedy-of-errors, to be sure. The Instructor was my OW Instructor, and knew it was my first dive ever on this gear, so it would have been much better to start with some other skill dives rather than the deep one. At least one of the other divers in the group had similar problems that day i.e. peak performance type stuff. It wasn't the first cold dive, just the first with the back-inflate BC. I've done lots of warm water dives with the same BC, of course sans ankle weights, and this isn't a problem.

I've also done about 10 more dives in Puget Sound on this gear since that day: and even though most were at Edmonds, (so - shallow shore dives) I still have been wearing the ankle weights because I don't want that to happen again. I really want to lose the training wheels, hate them....but the fear of the two dives on that day still haunt me many months later. The next dive was Cove Two at night....same day.......same problem.......only at night with swim-throughs and obstacles.......don't get me started.....eek.

Diving should be fun, right?

I appreciate your help!

 

[cdolphin]

I have no idea why an instructor would ever do the deep dive as AOW Dive #1...especially without first evaluating the skills of the students in the class (not sure if your instructor did this).

Did you ask your AOW instructor for some help with trimming out properly?
At 50+ dives, you're at the right experience level to be conquering this issue.

Have you tried doing a shorter dive in the 7mm semi-dry alone (without the shorty)? Just curious whether all that neoprene is making buoyancy control and trim more difficult.

Another thing to consider is that AL80 tanks can get "butt-light" as they are emptied. It's no excuse for an uncontrolled feet-first ascent, though.

An instructor here on SB (ae3753) has posted several wonderful essays that you might find interesting:

• Horizontal Trim 101 - Uses
• Horizontal Trim 101 - Levers
• Scuba 101 - Controlled Ascents

You should come away from that reading understanding that several variables can be changed in order to achieve good horizontal trim.

FWIW, at one time I used a very poorly designed rear-inflate BCD that trapped air in a very annoying way...and I knew where all of the dump valves were and how to operate them. I got rid of that BCD very quickly.

Hope this info helps...

Thanks for the links!

That was my 14th dive, several months ago. My instructor knew me from OW class, knew the gear situation, and the other two students were in rental gear. All three of us that day had problems. One with rapid air consumption and the other with peak performance/overweighted. That diver crawled on knees and fin tips back up the bottom (shore dive). We were all inexperienced, and did no shallow water check outs that day.


I've given thought previously to losing the shortie. I don't get cold, and it just restricts movement that much more. And I truly believe that it is part of the problem, maybe due to my body type.(?) I'm normal BMI, and tall. (female) I say it is part of the problem because I do fine in a 3mm in warm water with no ankle weights.

I hope it's not the BC...is this another LDS trick? No, it works fine in warm water, but it is a little tricky - like you have to get perfectly vertical to get all the air out and then I still can't use the low pressure inflator hose to completely empty it, I have to go to the shoulder dump valve. I learned that one in warm water.

The tanks were 80 Steels. To be honest, I just don't want to dive in Puget Sound anymore at all. Too many bad experiences. And I don't like to say that, because it's beautiful. I need better dives to convince me!

 

[Bubbletrubble]

It should be easy to exhaust air from your BCD. Perhaps your technique needs a little improvement or maybe a different BCD is in order, I don't know. Maybe an experienced diver in the local area would be willing to do a dive with you and help out a little. There appear to be a lot of friendly folks in the area...maybe...someone who might have already posted in this thread? Nudge, nudge, wink, wink. If NWGratefulDiver isn't available, maybe TSandM could help.

I suspect that the HP80 is part of your problem. That's a very short tank for a tall person. I realize it's so cute and light, but you will probably trim out better in an AL80 or HP100. Try a tank swap and see if that helps. You'll be surprised how different the rig feels.

I'd also try losing the shorty. Do a solid weight check before your next dive, though.

Good luck and let us know what ends up working!

 

[cdolphin]

Thx so much for your help Bubbletrubble. You're probably right about the tank, too.

There are many nice folks. I'm a bit jumpy after past experiences.....I know, I need to get over it, and get under!

TSandM's husband was my EAN class instructor.....I was looking for a new instructor after AOW, and just got lucky with finding Peter! But we didn't do any dives.

 

[TSandM]

cdolphin, would you be willing to come out and dive with me a time or two? I'd love to help you past the issues, if I can, and at least let you make a decision about diving here based on something better than gear problems.

One of the things that amazes me when I dive with novices (which I try to do when I can) is that most of the time, they have NO idea what dump valves they have on their BC, other than the inflator hose. As you learned, it's extremely important to know all the places where you can let air out of the bladder, because sometimes you just can't make the inflator hose work. Everybody should practice using all the dump options they have, until they can find them and make them work without having to think overmuch about it.

 

[cdolphin]

TSandM,

Thanks for that offer! I'll send you a PM. I'm not a cold water diver for the time being....

 

[Bubbletrubble]

cdolphin, would you be willing to come out and dive with me a time or two? I'd love to help you past the issues, if I can, and at least let you make a decision about diving here based on something better than gear problems.

TSandM,

Thanks for that offer! I'll send you a PM. I'm not a cold water diver for the time being....

Y'all are just too nice up there.
This is the Near Misses and Lessons Learned forum. Only strong opinions conveyed in a condescending tone are allowed.
Have fun, guys...
(I bet cdolphin is going to start enjoying cold water diving.)