The Art of Descent

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mccabejc

Contributor
Messages
1,326
Reaction score
3
Location
Upland, CA
# of dives
100 - 199
New guy, working on my buoyancy skills. Did an ocean dive today, 7mm wetsuit, AL80 tank, hood, booties, gloves, etc. I'm using 23 pounds total (20 integrated BCD, 3 on ankles).

I can descend, but only if, after deflating the BCD, I COMPLETELY exhale as much as I can from my lungs and hold it until I get down 5 or 10 feet. And if I then make a big inhale I tend to stop descending or even starting going up. If I do a shallow inhale I'm fine, but it just doesn't seem right to have to hold an exhale that long. And I'm pretty certain I'm not moving my fins at all.

Does that sound right, or should I add a couple more pounds?
 
At the beginning of the 1st dive of the day your wetsuit and gear won't be fully wetted and will have a bit of extra buoyancy. What you describe is pretty much what happens to me at the very beginning of the 1st dive of the day --- my wetsuit's extra buoyancy almost equals the extra 6 pounds of air in the tank.

What counts is how you are weighted towards the end of the dive when your tank is near empty.

If you can hold a safety stop, and make a controlled ascent to the surface with a near empty tank then you are weighted correctly.
 
I agree with charlie99. Also keep working on it and as you gain experience you will relax more and probaly won't need to add weight, instead you may find that you need to subtract weight.

I take it you have done a check and found that 23 is the correct amount for you in that gear.
 
Yep, that makes three, you are normal. Enjoyed having you with the group today. When I dive, I have to float verticle in the water for a bit to allow trapped air in my suit to work its way out. The titanum (knock of of the gold suit) liner does make a good tight seal. But what you describe is my normal dive.
 
But if I punch a hole in the top of my head, all the brains and stuff will come out...
 
I dive without weights! I'm wieghted perfectly in salt water. But fresh water I'm always negative. Not by much though. My BCD will still keep me neutral or positive. But only just. Hence I hardly dive in fresh water and for when I do, I'm having to get a new BCD which is a size bigger than my normal one (no I'm not growing before I get any smart replys) with the straps legthend so it fits properly! Does anyone no why I'm like this?
 
Mc,
That's pretty typical with a setup such as you are diving. I'm very cold natured and dive in a lake that, in the summer, ranges from 84-85 degrees at the surface to 52-54 degrees at 40 feet. One heck of a thermocline !!!!
I dive a 2 piece (farmer john/jacket) 6.5 mm wet suit. I dive a BP/W setup and with 12 pounds ditchable weight I actucall have to fin down just a little bit to about 13 feet before I get enough wetsuit compression to make a normal descent. This 12 pounds of weight is perfect at a 15 foot safety stop with 500 psi at the end of a dive.
I'd rather have the slight irritation of initiating the descent than having that of an uncontrolled ascent.
Play around with your weight just a bit, perhaps putting just a couple of pounds in trim weight on your tank. Might just make that wee bit of difference.
 
mccabejc:
New guy, working on my buoyancy skills. Did an ocean dive today, 7mm wetsuit, AL80 tank, hood, booties, gloves, etc. I'm using 23 pounds total (20 integrated BCD, 3 on ankles).

I can descend, but only if, after deflating the BCD, I COMPLETELY exhale as much as I can from my lungs and hold it until I get down 5 or 10 feet. And if I then make a big inhale I tend to stop descending or even starting going up. If I do a shallow inhale I'm fine, but it just doesn't seem right to have to hold an exhale that long. And I'm pretty certain I'm not moving my fins at all.

Does that sound right, or should I add a couple more pounds?

How are you at the end of the dive? Can you hold your safety stop depth and make a controlled ascent to the surface from 5 meters?

R..
 
jbd:
I agree with charlie99. Also keep working on it and as you gain experience you will relax more and probaly won't need to add weight, instead you may find that you need to subtract weight.

I take it you have done a check and found that 23 is the correct amount for you in that gear.

What jbd says, and then some!!!! As your experience increases and you feel calmer and more confident you will find that you need less weight! been through this myself ;)
 

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