Dropping weight as you improve...

[herman]

The more over weight a diver is the more skill they need actually. In an over weight scenario staying down is easier, but a diver will generally have more air in the bladder throughout the dive. This means each time a divers depth rises a bit and the air expands that diver will have a larger depth swing. Same can be said for compression. When ascending the same problem presents itself as the additional air expands as the diver nears the surface so they tend to shoot up since they have to vent more. Venting evenly is a skill that few posses out of the box so the less air a diver has the easier it is to ascend and maintain buoyancy in the water column.

Depending on several factors ideally you want to have zero air in your bladder at the end of a warm water dive. Couple quick pumps into the BC should be all a diver needs to slowly ascend.
The less air in the bladder, the easier to maintain a given depth and the easier to ascend. It is also a fairly easy process to get properly weighted for a given exposure suit/tank combination.

If you are neutral you should not add any air to your BC to accend. Remember, any air in your BC is going to expand as you accend and must be vented, otherwise you
may end up with an uncontrolled accent. Any wetsuit you are wearing will add to your problems on accent if you are doing a positive accent. Either start your accent with breath control or better yet, dump most of the air in your BC and accend using a gentle swim up, venting as needed on the accent. Swimming up a few pounds negative is a lot easier to control than a dead on neutral breath controlled accent. If you need to add a little back to get neutral for a safety stop fine but odds are you will need to vent even more is you are wearing much of a wetsuit.

Sounds like everyone has given some good advice. I would offer a general recap which is this:

1. Don't rush the process...if you drop too much too fast, you'll only complicate things and burn through air faster trying to stay down.
2. Remember that when you do your buoyancy check at surface that you have to exhale completely to drop below the water...that means that when you want to descend, you will need to exhale the air to drop down...many people tend to weight themselves so they can drop without exhaling...this could save you from some extra weight.
3. Remember that with alum tanks, they tend to get real buoyant the lower the psi...so remember to be safe and not deduct too much weight so you can't stay down with 1000 or less psi in your tank.4. Wetsuit thickness, drysuit type and or thickness all influence the amount of weight you might need to obtain the happy number. Add hood, gloves, boots and that too can influence the weight amount.

Bottom line is stick with comfort over bragging rights...I can dive with 10lbs and my 7mm suit and boots, but I won't. I don't want to struggle and burn through air fighting to stay down if a surge picks me up. So i tend to dive with more lbs for comfort. How much more...doesn't matter...it's what makes me comfortable.

Al's only get a couple of pounds positive when empty but when properly weighted, it is a mute point. The shift in buoyancy as air is used is what you have to compensate and weight for. That shift will be exactly the same for a given volume tank reguardless of material. The shift in an 80 cf tank is around 4 lbs. After doing a good weight check with a full 80 cf tank, adding 4 lbs to your weight will put you perfectly weighted at the end of a dive.

 

[victor]

Eric
My weighting will change over a vacation. I will start with 12 lbs,and I might struggle feeling a littlelight at the end of my first couple of dives.
By the middle of the week I will be very comfortable with 12 lbs and might drop to 10. After 2weeks diving I will be comfortable at 10 and could drop to 8.
I wear a dive skin, so no neoprene. When I switch to BP/Wing then I expect to drop a couple of pounds, my BC is buoyant,too much padding etc.

 

[cool_hardware52]

Wetsuits "gain experience" too.

Nothing is more buoyant than the new wetsuit the newly minted diver buys.

Squash it a few dozen times and it will be less buoyant.

Squash it a few hundred times and a 7 mm suit is now a 5mm, and a 5mm is now a 3mm etc.

Tobin

 

[boulderjohn]

Depending on several factors ideally you want to have zero air in your bladder at the end of a warm water dive. Couple quick pumps into the BC should be all a diver needs to slowly ascend.

Herman already pointed this out, but you should never have to add air to your BCD to ascend. If you do, then you are negatively buoyant. You should be able to begin an ascent either by gently kicking toward the surface or by inhaling deeply to start rising. Once you start to rise, you will continue to rise because of expanding air in the BCD, etc.

I am using this to illustrate something I tell my students to do. If you are neutrally buoyant in water with no real current, swimming should feel effortless. I tell them that at times they should just stop kicking, relax, and see what happens. In most cases, they will feel themselves sinking, meaning that their kicking efforts are going toward maintaining depth. They should add air to their BCD to become neutral. They should be able to hover in place with relaxed breathing at any time during the dive.

If they have to add air and already have a fair amount of air in their BCDs, then they are over-weighted. If you are diving in warm water with a relatively thin wetsuit, neutral buoyancy should require very little air in the BCD.

So, I recommend that process while you dive. If you find yourself needing to add air such as I describe, try dropping some weight on the next dive.

 

[warmwaterturner]

When I first began training I was in a 3mm Henderson and when all geared up (fresh water) was at about 12#'s. Now (in fresh) I use 4# with an AL80. Not really sure why because my SAC has always been very low. Perhaps there is some other metabolic explanation to boyance than holding ones breath or breathing rapidly. I like to think it might also have something to do with the amount of oxygen being carried in the blood stream when nervious - body preparing for fight of flight....you know.

 

[TSandM]

In most cases, they will feel themselves sinking, meaning that their kicking efforts are going toward maintaining depth. They should add air to their BCD to become neutral. They should be able to hover in place with relaxed breathing at any time during the dive.

This is definitely ideal. The caveat is that, if the diver is maintaining a posture in the water that is significantly feet-down/head-up, the minute they kick, they'll drive themselves upward. I believe this is a large part of the reason that novice divers often dive negative. On the other hand, it's a double whammy, because I know from experience that it can feel much more secure to be negative and swimming up, because neutral buoyancy can seem awfully tenuous when you are new . . .

 

[Dhboner]

I went from 29lbs to 17 lbs in around 20 dives (full 7mm with hood and gloves and AL80). The key was fully understanding the buoyancy of my lungs. Once I learned to fully exhale at the start of a dive to initiate the descent I found I could start to drop lead. The other key factor was realizing that the size of the "bubble" in my BC was making the task of achieving decent trim a total pain. So less weight meant less air in the BC..less air in the BC meant less dramatic buoyancy shifts as I ascend/descend.

The other day I was having a little fun at the end of a dive with around 450 psi...I was hovering stretched out on the surface near shore (as if I was snorkeling) and I was exhaling to slowly descend and inhaling to begin a slow ascent. After a few tries I was stopping the descent with an inhale before reaching bottom and then descending in small increments with short exhales. I know it sounds stupid but I was getting really "tuned in" to my control over my buoyancy.

Bob

 

[RJP]

Any comments on this subject would be appreciated. When did you all start removing some weight from your BCD/belt? Do you notice a big difference with 2 lbs less; 4 lbs less, etc? Did your air consumption improve noticeably with less weight?

Thanks!

-Eric

Spend a lot of time at the end of a dive in shallow water. I mean REALLY shallow. Like 5-10ft on a shore dive. Swim around and check stuff out, while removing a pound or two here and there.

This will give you four benefits, that are all related

1. Getting your buoyancy control dialed in
2. Getting your trim dialed in
3. Getting your weighting dialed in
4. Getting yourself comfortable with 1-3 above

Most new divers don't realize how inter-related all these things are. Most overweight themselves because the can't control their buoyancy themselves, so they look to lead to do it. Classic "gear solution to a skill problem."

As Lynn points out, being out of trim will cause you to either swim up or swim down. Get your trim worked out and you will eliminate those two factors

THEN you can get your weighting dialed in.

Lastly, doing these things in a narrow window (5' to 10' of depth) will give you the comfort and confidence that you CAN do it. Being horizontal and being neutral are not things that humans are used to. We spend our lives vertical and firmly on the ground. Being neutral feels very unnatural at first, and therefore somewhat scary. When you are not planted on the ground, you feel like you are floating up. Once you "recalibrate" yourself to no longer believe you are floating up, you'll be much more comfortable and then really be able to shed the lead.

Ray

 

[Reef Tank]

Wetsuits "gain experience" too.

Nothing is more buoyant than the new wetsuit the newly minted diver buys.

Tobin

And, not every 3mil full is the same. My super stretch is not totally closed cell and it soaks up water after a little time under water so it obviously will not be as buoyant at the end of the day.

 

[Scuba.com]

The biggest thing I like to tell students I work with when it comes to this is practice, practice, practice. If it is a possibility for you to dive frequently, that is an easy thing to do. For instance here in Southern California, and when I originally learned to dive in Puget Sound access to a dive was simple. Drive to the dive site and walk into the water. Several friends and myself used to work Swing shift, so we'd often dive before work, get a tank fill on the way to work, then make a night dive again before heading home to bed. We were young and single with little else to do. With that type of access to scuba, it's easy to experiment. Basically keep note of what you are diving with in terms of the type of cylinder and gear, when you felt you were negatively or positively buoyant and the next time making an adjustment on your weight belt of a couple pounds, then doing it all over again. We'd make notes on a small dive slate and compare later on.

With a little bit of practice we found it didn't take a lot of time to have ourselves all trimmed out in the water and at the same time had continued working on the skills that make diving fun.