Noob neutral buoyancy and trim ponderings

[rfwoodvt]

Morning all,

Got myself (finally) some gear I am confident in: Zeagle Ranger BC, a Bare step through shortie (7mm) to wear under my Quicksilver 4/3 full suit.

Took it to the local pond this weekend to work on by Neutral buoyancy and trim. Hopped in with 800psi in my al80 tank and 26 pounds of lead, 12# in the trim pouches at lower end of tank and the remainder in the ripcord pouches in the front.

Anyhow, here are my questions:

1. 26 pounds put me eyeballs level with the water in an empty BC (850 psi in tank) and full lungs. Empty lungs had me slip below the surface but didn't seem to let me descend much more than a foot or two. Should I add more weight or is this the right relative bouyancy?
2. 26 pounds seems like a lot, but with the near 12mm of wetsuit on my torso maybe not?
3. Hovering at 10 feet seemed very tenuous, as there was a very fine line, indeed sometimes no line, between enough air in the BC and an elevator ride to the top. I'd add a puff of air and all would be fine, then perhaps take a deep breath, let it out and it was a one way trip topside, even when dumping all the air from my BC. Is this a function of the shallow depth or might I be doing something wrong?
4. The Ranger trim weight pockets appear to be intended for mounting only to the bottom tank strap on the Ranger. Can they be mounted on the upper tank strap and if so, what's the best way to do that? (the manual doesn't show that as an option btw)
   
5. no matter how I trim out (so far) my feet and knees always hang down. I'm guessing that I need to move more of the weight to shoulder height or above, is that correct? If so, can I add trim pouches to the top tank band in addition to the lower trim pouches?
6. what percentage of my lead should be in the quick-ditch pouches?

I appreciate any and all insight!

Rick

 

[formernuke]

The only part I'll comment on is the weighting part.

The eye level test is supposed to be done with a FULL tank, not empty. Remember there is a swing between full and empty and you weight yourself for empty.

Try the test with a full tank then dive the empty test is 500psi at 15 feet with no air in BC.

As for where to place the weight you have to experiment around and see what works for you

 

[Scuba-74]

Just some thoughts, in no particular order.

Quicksilver makes surf suits, not dive suits. I've never seen a person diving in a Quicksilver suit. It doesn't mean that you can't dive in one, but most likely the characteristics of the neoprene (ability to withstand pressure) are less than ideal for diving. It may be alright for the pond, but may become an issue for deeper dives from both temperature and weighting perspective.

26lb sounds like a lot, but for a newer diver it may not be a gross overweighting. I just happened to do a lake dive with al80 a week ago, and I used 16lb with 7mm, hood, and gloves. But I do also have heavy fins, with lighter fins I could have used more. So, same ballpark, more or less.

It is very strange that your descend stops at 1-2 ft. As we all understand, the deeper you are, the easier the descend should be with all other things being equal.

I tend to keep 1/2 to 2/3 in the front pouches. It is both convenient and safe, as trim pouches aren't easily ditchable on Zeagle. You can place weights on the upper strap, but I've never heard of anyone placing weights at "shoulder height" and certainly not above it.

 

[Raphus]

if you can descent for 1 feet you can descent for 1000 feet.

If you did descent, you were negatively buoyant. And this won't change. If you go deeper, you suit compresses and you will be even more negatively.

I see a lot of beginners with this problem.
Sometimes they inhale, which makes them positive again and they stop the descent, or even ascent to the surface.
But more often, they move their fins and fight against their descent. This is most of the times not intended.

Exhale. Don't move and dont/slowly inhale when you descent,so you lungs are not that full. After 3ft you can start to breath normally, because usually the suit is compressed enough to make you more negatively buoyant.

26lb is a lot of weigth. Try to make the descent happen and then lower your weigth until it does not longer work.

 

[inquis]

I'd add a puff of air and all would be fine, then perhaps take a deep breath, let it out and it was a one way trip topside, even when dumping all the air from my BC. Is this a function of the shallow depth or might I be doing something wrong?

Buoyancy changes more quickly at shallow depths. Your trim issues may be complicating buoyancy, as a slight kick for stability will direct you upward. Try hovering with ankles crossed to isolate the two effects. (If that puts you vertical, so be it.)

Work out the trim issue after buoyancy is fixed. Yes, you can put trim pouches on the upper tank band where they have more of an effect.

 

[Kupu]

Got myself (finally) some gear I am confident in: Zeagle Ranger BC, a Bare step through shortie (7mm) to wear under my Quicksilver 4/3 full suit.

Are you using brand new wetsuits? If so, you will likely be needing to extra weight during the first few dives, as factory new wetsuits tend to be extra buoyant. The extra weight can be removed bit by bit over the course of the first 10 or so dives as the wetsuit compresses from use.

When using a new 5/4 I start out with an extra 6lbs to compensate.

 

[inquis]

what percentage of my lead should be in the quick-ditch pouches?

Enough to enable you to ditch and swim up if your BC fails. Worst case is at the beginning of the dive (still carrying the weight of the air you haven't yet breathed) on the bottom (where wetsuit buoyancy is lowest). Non-reserve air in an AL80 tank weighs 5 lbs. You can measure your wetsuit's buoyancy in a pool or hot tub, and the conservative approach is to assume you lose it all. I would guess most people can swim up while 10 lbs negative. So if suit is 23 lbs, worst case is 28 negative, IF properly weighted. You would therefore want 18 lbs ditchable.

Ditching weight at depth is controversial, however. The issue is you will then be 18 lbs positive at 15 ft (in this example) and unable to halt your ascent, increasing the risk of DCS. (You would be swimming DOWN at that point, trying to slow the ascent; but with only 10 lbs of thrust, that's still a net 8 lbs positive.) While bent is better than drowned, redundant flotation (e.g., a DSMB) may allow you to make a controlled ascent with safety stop, without dropping any weight.

 

[Moerae]

Morning all,

Got myself (finally) some gear I am confident in: Zeagle Ranger BC, a Bare step through shortie (7mm) to wear under my Quicksilver 4/3 full suit.

Took it to the local pond this weekend to work on by Neutral buoyancy and trim. Hopped in with 800psi in my al80 tank and 26 pounds of lead, 12# in the trim pouches at lower end of tank and the remainder in the ripcord pouches in the front.

Anyhow, here are my questions:

1. 26 pounds put me eyeballs level with the water in an empty BC (850 psi in tank) and full lungs. Empty lungs had me slip below the surface but didn't seem to let me descend much more than a foot or two. Should I add more weight or is this the right relative bouyancy?
2. 26 pounds seems like a lot, but with the near 12mm of wetsuit on my torso maybe not?
3. Hovering at 10 feet seemed very tenuous, as there was a very fine line, indeed sometimes no line, between enough air in the BC and an elevator ride to the top. I'd add a puff of air and all would be fine, then perhaps take a deep breath, let it out and it was a one way trip topside, even when dumping all the air from my BC. Is this a function of the shallow depth or might I be doing something wrong?
4. The Ranger trim weight pockets appear to be intended for mounting only to the bottom tank strap on the Ranger. Can they be mounted on the upper tank strap and if so, what's the best way to do that? (the manual doesn't show that as an option btw)
   
5. no matter how I trim out (so far) my feet and knees always hang down. I'm guessing that I need to move more of the weight to shoulder height or above, is that correct? If so, can I add trim pouches to the top tank band in addition to the lower trim pouches?
6. what percentage of my lead should be in the quick-ditch pouches?

I appreciate any and all insight!

Rick

Overall you have the right idea and are taking the right approach. I'll copy something I wrote in another thread as I think it might be helpful for you.

I'd give this a shot or two before assuming you're doing things wrong. This stuff takes practice and it's expected and OK if things seem hard at first or "don't work". Focus more on weight and buoyancy before figuring out trim.

• Over weighted
  • Common issue for new divers
  • Amplifies other problems (e.g. you'll troubleshoot a problem but the root cause is still being over-weighted)
    
  • Can be one of the causes for your issue for a few reasons
    • You fully deflate and sink like crazy since you are very negatively buoyant (vs only a little negative when weighted properly)
    • The gas in your BCD compresses as you descend. The more gas you need just to stay neutral, the more dramatic the effect of that compression/expansion has on your buoyancy. So even if you're neutral at some point, after a few feet you'll start to sink/rise faster and faster as the gas compresses or expands. This can cause runaway ascents/descents that can be hard to manage.
  • Solution (fixing this first will make practicing everything else easier):
    • Do this in an easy location where you can take your time. I find easy shore dives (protected cove or lake) are good for this (not a lot of surge, current, etc)
      
    • To get the minimum weight you need to dive, go to a place that has a 12-18ft bottom (15ft is ideal). You can do it off a boat with a good buddy but I prefer a shore dive since you aren't in a rush or anything, and it's easier IMO.
    • At the end of the dive, with around 500 psi, empty all the air our of your BCD. Get it totally empty.
    • If you're in a drysuit dump air until you've got the minimum air to be comfortable and warm.
    • Start removing a little bit of weight at a time (easier if you do this exercise with pouches)
    • After removing weight, wait a second, and see if you can go up and down with your breathing alone
    • If you can't control your buoyancy comfortably (without excessive inhalation), remove more weight
    • Once you hit the point where you feel too light, meaning even slight inhales start to cause you to rise up, add back 1lb at a time until you can breath comfortably while gently rising and falling. That's "neutral".
    • Repeat this exercise every once in a while as your breathing and buoyancy control gets better (you'll likely need less weight).
    • Repeat this exercise when you make big gear changes (drysuit, different mm wetsuit, different tank size/type, etc).
• Over-relying on your BCD for buoyancy
  • Common issue for new divers
  • Compounds with being overweighed, but still an issue if you're not overweighted
  • Are you frequently are adding and removing air from your BCD during your dive? Do you end your dive by adding air, and begin your descent by rapidly releasing air until you start descending?
  • Solution (easier to practice if you're not overweighted):
    • Do this in an easy location where you can take your time. I find easy shore dives (protected cove or lake) are good for this (not a lot of surge, current, etc)
      
    • Step 1
    • Descend to 10-15 feet normally, however you do it now.
    • At the bottom, get neutral and practice hovering a few feet of the bottom. If staying still is hard, that's ok. Lightly moving forward/in a circle is Ok. Eventually try to do this staying still.
    • "Play" with the air in your lungs and how it impacts your buoyancy. Take a deep full breath and feel yourself rise. Exhale fully and feel yourself sink. Try breathing "full", keeping lungs 40-80% full (don't do this for long, full exhales are important to get rid of CO2). Try breathing "shallow", keeping lungs 20%-60% "full". In both cases you should gently move up and down, but a little more up over time or a little more down over time depending on full/shallow.
    • Once you're comfortable with this, and can manage your buoyancy with a 5ft swing up and down without using your BCD, go to step 2.
    • Step 2
    • Get positively buoyant at the surface.
    • Test your regulators at the surface with five good, full breaths, and watch your SPG (if it drops dramatically or wiggles when breathing check your valve is open all the way). You'll be descending with empty lungs so you don't want a surprise when you try to inhale.
    • At the surface, over a 10-15 foot bottom, release only a little air at a time from your BCD. If you start to sink, add a tiny bit more back in.
    • Each time you release a bit of air, wait a second, and then completely and forcefully exhale air out of your lungs. If you start descending, then don't release any more air from your BCD. And don't take any deep breaths. Leave your lungs empty for a few seconds as you descend. Make sure you aren't kicking sub consciously.
      • Let yourself descend a few feet and then take a slow, shallow breath. If this makes you shoot back up to the surface that's OK. That's why you're practicing.
      • Try again a few times, see if you can descend down to 10-15 ft without releasing any more air from the BCD.
      • Try again, but this time, control your breathing like you did in step 1 and see if you can descend down to 10-15 feet, and then hover, without using your BCD, only your lungs. .
      • When you go deeper, do the same thing for your initial descent from the surface (Just enough air in BCD that you can exhale to descend), only this time add tiny shots of air to the BCD as you descend. But only add enough air so that you can control your buoyancy primarily with your lungs. Exhaling at any time should make you descend, inhaling should make you ascend.
      • At any time you should be able to stop going down by breathing in deeply, or stop rising by exhaling fully.

 

[Diverlady13]

Regarding your trim, you'll likely need to experiment a bit. I have very muscular legs without much fat on them (so they aren't buoyant). Plus my fins are heavy so my legs tend to want to hang down in the water. It doesn't help that my chest is pretty buoyant. I have a Zeagle Zena BC which has 2 tank straps rather than just one. To compensate for the extra buoyancy in my upper body, I moved my trim pockets to the top strap and put a couple of pounds in those (and decrease the weight in my pockets. It definitely helps me stay more flat having a bit of weight moved upwards. When we dive again in a few weeks, I'm going to try reducing my overall weighting by 2 lbs and try putting 4 pounds on my back and then the rest in my pockets. I've been diving with 16 lbs of lead, but I think I can move down to 14 lbs total now that my buoyancy is substantially better. I had to use 18 lbs when I first bought the wetsuit because it added so much buoyancy. Now wetsuit has enough dives that I should be able to drop a couple more pounds and be just right.

 

[NorCalDM]

Moving weight around will help your trim depending on where you place the weight. Also a standard aluminum cylinder is light in the bottom so moving it down can help get your legs up but if it is an aluminum neutral this won't help. The amount of weight you carry is very dependent on your body and how much you weigh and if that weight is muscle or not. The amount of weight you carry will also increase in salt water as I'm assuming the pond is fresh water for me this is a 4 pound difference.