Something's wrong with my bouyancy?

[Degenerate]

There were times where I jumped off the boat with completely deflated BCD + 14lbs, I still float back up without even kicking.

If you are positively buoyant at the start of the dive with 14lbs you would be even more positively buoyant at the end of your dive.
Don't be too bothered about the people telling you that 14lbs is too much weight, all of us are built different and two people with the exact same gear will most likely need different amounts of lead.
I'm gonna go against all the people you dive with who say 14lbs it too much and say that I think it might not be enough.

 

[Eric Sedletzky]

Pick some heavier fins.
Your weighting should be such that at the end of the dive with a near empty tank you should be able to hold a 15’ stop with no air in your BC and control your buoyancy with your breathing alone.
Whatever combo of weight you need to achieve this is what is required. Whatever that turns out to be at the beginning of the dive doesn’t matter.
Where you choose to place the weight is up to you.
I personally like weightbelts and I like to break up my weighting between my BC and my body.
I don’t like the idea of having all my weights on the rig, and I especially don’t like the idea of no ditchable weight.
FYI, I dive in 49 degree water in a full 7mm wetsuit with a hooded vest, booties, gloves, the works.
Also, use the heaviest steel tank you can find appropriate for your body size.

 

[alex_can_dive]

This is what you can do the next time you dive:
- be sure that, before descending, you completely empty your lungs
- be sure that you do not move any muscle when you descend
If you don't manage to descend by doing so, you probably need more weights

Thanks! I'll try these tomorrow!

One question about empty lung. How do I equalize if I keep my lung empty? (I have this irrational fears of ear pains, so I always equalize as soon as I feel any pressure change, even if it doesn't hurt yet)

 

[alex_can_dive]

Pick some heavier fins..

Anything I could do to make my legs/fins heavier? I love these fins and don't want to return them because they're the only pair I found comfortable and efficient to swim with. (after testing out 10 different pairs)

 

[JohnN]

Anything I could do to make my legs/fins heavier? I love these fins and don't want to return them because they're the only pair I found comfortable and efficient to swim with. (after testing out 10 different pairs)

I'm surprised no one has mentioned ankle weights. . .

Maybe your instructor friends have some you can borrow

 

[ginti]

Thanks! I'll try these tomorrow!

One question about empty lung. How do I equalize if I keep my lung empty? (I have this irrational fears of ear pains, so I always equalize as soon as I feel any pressure change, even if it doesn't hurt yet)

I don't think it is actually possible to empty your lungs at 100%.

Anyway, the most difficult part of the descent is the very beginning. Take a breath as soon as you are one/one and a half meters underwater, just pay attention to avoid filling your lungs to their maximum.

I don't like ankle weights, but my fins are quite heavy. If you don't find anything better, go for them, but I recommend first move your weights closer to your centre of buoyancy if they are far (that is, try a belt or something that brings your weight down).

Anyway, first, be sure that your weight is appropriate (e.g. that you can descend)
Then, think about weighting distribution (e.g. use a belt, ankle weights or whatever you want)

 

[JohnN]

I don't think it is actually possible to empty your lungs at 100%.

Anyway, the most difficult part of the descent is the very beginning. Take a breath as soon as you are one/one and a half meters underwater, just pay attention to avoid filling your lungs to their maximum.

I don't like ankle weights, but my fins are quite heavy. If you don't find anything better, go for them, but I recommend first move your weights closer to your centre of buoyancy if they are far (that is, try a belt or something that brings your weight down).

Anyway, first, be sure that your weight is appropriate (e.g. that you can descend)
Then, think about weighting distribution (e.g. use a belt, ankle weights or whatever you want)

Absolutely agree about ankle weights, and this is yet another reason why a BP/W is superior to a poodle jacket. The BP/W gives you the flexibility to adjust where the tank rides vs. your center of buoyancy

 

[johndiver999]

I use a high-pressure steel tank (100 cf) - from their spec:
Buoyancy Full: From -2.64 lbs. to -9.41 lbs.
Buoyancy Empty: From -0.66 lbs. to +2.35 lbs.

then 14 lbs sounds about right. Especially, if you are a female, women are often less dense than men, especially 120-lb ones. They also tend to have more buoyant legs and butt than men.

If you need 14 (or 16 lbs) that is what you need. To be honest, wearing 2 or 4 lbs extra above the absolute minimum amount you need is really not a big deal; at all. Before you spend a bunch of money on fins, ankle weights etc. I would start with a borrowed weight belt worn on your hips as low as possible with maybe 8 or 10 lbs on it.

 

[SlugLife]

Trim is influenced by where the weight is placed, and is your angle/tilt in the water. Amount weight determines how positively or negatively buoyant (float or sink) you are.

While 14lbs seems high at first glance but it could actually be correct. There are no hard rules or easy calculations for the right amount of weight for a person. The buoyancy check gives you a starting point, but you may still need to add or subtract weight based on how buoyant you are at the end of a dive. Your wetsuit is rather thick, and probably adding a lot of buoyancy, especially if there is air trapped. You might also have a little bit of air trapped in your BC. Factors that can reduce extra weight needed are things like having a steel backplate or heavy equipment.

IMO, the most accurate buoyancy check is at the end of a dive, when you're doing a safety stop with close to 500psi. If you are positively buoyant at 15ft (5-meters) with no air in your BC, that's a little dangerous and harder to control. However, if you're at 15ft, 500psi, and dump all your air, and sink easily or quickly, you might be able to dump some weight. If you do find you're light at your safety stop, go down a little closer to 20ft.

You could try taking a deep breath, then exhaling, and maintaining about 20% lung capacity. Make sure you aren't moving your fins at all, perhaps place your ankles together. See if there's more air in your BC that is trapped, that you could be dumping.

 

[rick00001967]

are you sure the tank you are using is a high pressure 100 ? cuz if you are, something doesn't seem right here. those are very heavy tanks. and they do not become positive at any time.

you said you are wearing a 8/7mm suit ? is it a one peice, or are you wearing two layers ? what exactly are you wearing ?

at home i dive a low pressure 77. so it would be lighter in the water than the HP100. if i wore a full 7mm wet suit with hood and gloves, i would be adding about 14 lbs of lead. and i am about 180 lbs.i add about 18lbs with my dry suit and cold water undies.