Not only do AL 80s get floaty, they especially get floaty at the tail end (towards your feet). This likely contributes to your problem. Here are a couple of solutions. Consider putting a band on the bottom of your tank with a couple of weight pockets and then move 2-4 lbs of weight those pockets at the bottom of the tank. You could also try a heavier set of fins.
Trouble w/ inversion at Safety Stop
- Thread starter Kyle0692
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This is not the same as equalizing your ears or clearing your mask, where any of multiple acceptable methods are fine as long as they work.
A buoyant ascent is NOT a controlled ascent. Even though you are successfully controlling it anyway so far, you can too easily slip over into an uncontrolled rapid ascent. This is even more pronounced in the shallower portion of the water column, where the pressure differential per foot (and the expansion of air, and the associated risk) increases as you ascend. And in your case, since you are using air to ascend, I now suspect it is more likely that you might still have air remaining in your BCD that you could access with a lower dump valve, rather than the inflator hose or a shoulder dump. You also mention "less work." If swimming to the surface is difficult, you are too negatively buoyant. That may mean too much weight, or it may just mean you need more air in your BCD. But don't swing to the other extreme, with too much air as the remedy for too little.
So I am not a tech diver, nor do I dive BPW, so maybe there is another school of thought when training in those contexts. But the only place we learn/practice a buoyant ascent in PADI recreational courses is a very specific scenario for Rescue Diver.
Do you use a dive computer? If you download the logs, I am curious what is says your buoyant ascent rates are. Most computers will redline at 30 ft/min, either for the whole ascent, or at least for the shallower portion.
OP
Kyle0692
Contributor
Yes, I have a computer and it does alarm at > 30 FPM. I watch the computer while I ascend and it doesn't go in to alarm on me. Looking at my log from my last dive, I went from 80 ft to 15 ft in about 7 mins. My buddy I was diving with I had not been diving with before and he was having problems ascending. He would make a little progress and then sink back down so it took awhile to get up to safety stop depth. I probably confused you with the positive buoyant part. I'm more neutral than anything. I had just meant by the positive that when I start ascending quicker (slightly positive) I dump air to be neutral again. When I'm going up I keep my lungs slightly fuller and watch my computer, as my ascent rate rises I can dump air from the BC in short bursts as needed to stay in control so if I need to stop at a given depth I can, easily. Basically I am doing the reverse of when I descend, adding air in short bursts to my BC so by the time I'm on the bottom I'm very close, if not already neutral.
OP
Kyle0692
Contributor
Found a YouTube video that basically shows how I ascend. Starts at 0:38
Okay, I just watched the video, and now I know that there is at least source out there preaching a buoyant ascent. I have never heard of UCPA before, and don't find much with a Google search. So now I wonder if they are an outlier on this one issue, or if this method is more common than I think. I also don't see them listed on the WRSTC/Europe page.
European Council - WRSTC
I will also point out that my understanding of your ascent is not quite the same as what is shown in this video. I believe you have described your ascent as being oriented relatively flat and level, whereas this video shows heads up and feet down. If so, we are still back to the possibility that you are trapping air in the lower corners of your BCD, and allowing those corners to rise higher than your shoulders as you ascend, and then increase in volume/lift under reduced pressure.
UCPA is not a diving association. It is a non profit French organisation, which makes sports holidays of all types, that includes diving as well.
UCPA - Wikipedia
Yes, sort of. You are after all ascending, and breathing as you ascend, so your buoyancy is constantly changing. Ascent should involve some gently finning, along with management of air in the BCD.
Every reference in the PADI OW course is to slowly swim up, nothing about drifting up. I tell my students they need to take the stairs - no elevator rides.
There are two common obstacles teaching proper ascents: first is to get students to NOT inflate on the way up - there is always at least one in every group. The second is to get students to NOT dump ALL their air on the way up and struggle to swim up. Especially those who have not yet developed good fin technique and look like they are trying to climb a ladder...
One question I have is what exposure protection are you wearing? If you are wearing a thin wetsuit and have to add air to your BC you may be over weighted also an aluminum cylinder is more buoyant on the bottom so moving it up may help or distribute more weight to the hips not adding weight just distribute it different. Ankle eights could help depending on what type of fins you are using "negative or positive".
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