Weight issue

[skywalk]

Hi folks,

i would like some opinion on how you all deal with buoyancy changes with a full tank vs empty tank.

Here's the thing: With a full tank and 2 weights, i sink like a rock. have to inflate my BCD quite significantly, but when i'm on 50bar, i have perfect buoyancy with pretty much zero air in the bladder, at around 3-5m.

with 1 weight, i can still sink quite easily with a full tank, but when i'm on my safety stop and at 50bar on an empty bladder, I am so positively buoyant that I have to constantly either keep totally exhaling to stay neutral, or fin downwards.

i hate being overweighted. with either 1 or 2 weights, i always have a "window" of perfect weighting, but as I drain my tank of air, I am faced with this choice...
1) be overweighted at the start and perfect at the end, or
2) be perfectly weighted at the start but slightly too buoyant at the end.

would love your input. thanks.

 

[DiveMaven]

How much does each weight weigh?

 

[Noviz]

Hi... If you are neutral at the start of the dive and can still be neutral at the end by "totally exhaling to stay neutral, or fin downwards", there ain't a darn thing you can do to "fix" it. Air weighs what it weighs. You're looking at what, a 4 lb swing? (Unless you have the world's biggest lungs). Unless you dive neutral and pick up 4 pounds of rocks before you start up, you seem to be out of options. (BTW - it's been done.)

 

[The Kraken]

You need to be neutrally buoyant at the end of your dive, regardless of the weight swing during the dive.

Diving a thick farmer john/jacket can be particularly problematic due to the loss of buoyancy from the compression of the neoprene when the diver hits about 10-15'.

the K

 

[Sideband]

If you are properly weighted you will be heavy at the beginning by about 4 to 6 pounds and will end the dive neutral. If you are sinking like a rock, don't let out so much air from the BC. Only vent enough that you start to sink when you exhale.

Joe

 

[donacheson]

Hi folks,

i would like some opinion on how you all deal with buoyancy changes with a full tank vs empty tank.

Here's the thing: With a full tank and 2 weights, i sink like a rock. have to inflate my BCD quite significantly, but when i'm on 50bar, i have perfect buoyancy with pretty much zero air in the bladder, at around 3-5m.

with 1 weight, i can still sink quite easily with a full tank, but when i'm on my safety stop and at 50bar on an empty bladder, I am so positively buoyant that I have to constantly either keep totally exhaling to stay neutral, or fin downwards.

i hate being overweighted. with either 1 or 2 weights, i always have a "window" of perfect weighting, but as I drain my tank of air, I am faced with this choice...
1) be overweighted at the start and perfect at the end, or
2) be perfectly weighted at the start but slightly too buoyant at the end.

would love your input. thanks.

The correct answer is (1). In a bit more detail, minimum weight is that which you need to be neutral just below the surface with an empty BC, near-empty tank, and breathing normally. Then you can do a safety hang in comfort and ascend to the surface under control.

 

[spectrum]

The defining moment of the dive is at the end with a near ampty cylinder (500 PSI+-) If you have just enough weight to stay down at that point then whatever is needed at the start of the dive is not excesssive. The loss of air mass combined with neoprene compresion is why you have a Buoyancy Compensator, just use it.

Pete

 

[Midnight Star]

To help us understand your bouyancy problem more, can you tell us what type of wetsuit or dive skin your using? The type and thickness will greatly effect your buoyancy.

-----

Mike.

 

[Dive 'N' Dolphin]

Hi folks,

i would like some opinion on how you all deal with buoyancy changes with a full tank vs empty tank.

Here's the thing: With a full tank and 2 weights, i sink like a rock. have to inflate my BCD quite significantly, but when i'm on 50bar, i have perfect buoyancy with pretty much zero air in the bladder, at around 3-5m.

with 1 weight, i can still sink quite easily with a full tank, but when i'm on my safety stop and at 50bar on an empty bladder, I am so positively buoyant that I have to constantly either keep totally exhaling to stay neutral, or fin downwards.

i hate being overweighted. with either 1 or 2 weights, i always have a "window" of perfect weighting, but as I drain my tank of air, I am faced with this choice...
1) be overweighted at the start and perfect at the end, or
2) be perfectly weighted at the start but slightly too buoyant at the end.

would love your input. thanks.

I have a problem with being to Buoyant so I usually start out a little over weighted but at my safety stop I am not struggling to hold it. I would rather be a little over then risk being sucked up and unable to do a proper safety stop. Last thing I want to do is get hurt.
My 2c
Stacy

 

[jeffrey-c]

DAN has a good article on buoyancy control and weighting:

http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=28