A lesson demonstrated

[spectrum]

I stumbled upon the demonstration of an important concept that I'd like to share with new divers.

You should know that changes in buoyancy do not have an immediate result. As you rise or fall in the water column you have momentum and a minor change in buoyancy will need time to alter your movement.

I was at the pool, I had finished my laps and was winding down before doing some bottom swim runs. I was hanging on the edge in the deep end with fins, mask and snorkel. While holding the edge just enough to have a positional reference I exhaled, nothing happend for a VERY noticable time periods (2+ seconds) then I dropped. Took a deep breath, nothing for a spell and then up I came. I have known and understood this for along time but doing the test with a solid reference really drove home how palpable the delay is.

So if you find yourself chasing back and forth with your inflator buttons try this exercise, it will give you a real sense of how slow you need to go in making adjustments.

Pete

 

[H2Andy]

yup, you're exactly right

make a small change, wait, see the result

adjust as necessary

which is why thinking ahead and knowing what you're gonna have to do
in a few seconds bouyancy-wise is so important! you need that time
for your changes to take effect

 

[Mike Newman]

Ah - the lightbulb moment! Delighted to see that the theory is coming good for you. Isn't SCUBA just the greatest thing?

 

[TSandM]

The corollary is, of course, that the time to make the correction is before the unwanted movement has begun. It takes some time to relax enough to feel the changes in your gear and/or your drysuit that precede the movement itself; even better, notice that you have unconsciously changed your breathing pattern to compensate for what's going on with your buoyancy otherwise. Then you can add air, or vent, early enough so that you never leave the depth you want to maintain.

 

[Cacia]

Lynne, thats why I like to see people dive and orally inflate a BC. They really get this "feel" quickly with this little exercise. Gets them off the up/down elevator thing, with the minute effective volumes.

 

[ScubyDoo]

Reminds me of the old fin pivot exercise, which everyone should still practice today regardless of certification level... I was taught (as I hope all were)..to inhale while descending...and exhale while ascending (due to time delay). Its always worked well for me..

 

[H2Andy]

Reminds me of the old fin pivot exercise, which everyone
should still practice today regardless of certification level..

why? i've never needed to fin pivot in any of my dives... why not practice
breath control and bouyancy while off the bottom, which is how we spend
(hopefully) our entire dive?

 

[TSandM]

Yes, I'd have to say that the downside of the fin pivot is the foot low position -- building a proprioceptive memory of NOT being horizontal. The same exercise can be done horizontal, and simply inhale and rise off the bottom; exhale and your torso should touch first. Hmmm . . . based on the problems with my trim, maybe I ought to practice that myself!

 

[drglnc]

fin pivot is taught as a beggining to bouoncy control it is continued with a hovering skill. but you got the point slow and deep breaths make the difference but take a min to respond.