Let's discuss peoples over-reliance on BC's and over-weighting.

[Kevrumbo]

The Pedagogy of Neutral Buoyancy: How to properly teach and develop controlled horizontal trim & propulsion techniques in only 3 hours.
UTD Extreme Scuba Makeover (ESM)

 

[Nasser Beloush]

Please excuse my ignorance but how can you compensate for buoyancy loss due to wetsuit compression underwater if you aren't using a BC or a drysuit, wetsuit only? If the diver who isn't using a BC starts as neutrally buoyant at the beginning of the dive, how do they stay neutrally buoyant at depth without a BC?

 

[BRT]

Please excuse my ignorance but how can you compensate for buoyancy loss due to wetsuit compression underwater if you aren't using a BC or a drysuit, wetsuit only? If the diver who isn't using a BC starts as neutrally buoyant at the beginning of the dive, how do they stay neutrally buoyant at depth without a BC?

You just have to be a really good diver.

 

[Killerflyingbugs]

That would be slight adjustments at depth.

 

[Kevrumbo]

Please excuse my ignorance but how can you compensate for buoyancy loss due to wetsuit compression underwater if you aren't using a BC or a drysuit, wetsuit only? If the diver who isn't using a BC starts as neutrally buoyant at the beginning of the dive, how do they stay neutrally buoyant at depth without a BC?

Staying above that depth where wetsuit compression becomes a problem, or physically continuous kicking and/or holding breath (which obviously is never a good practice when breathing compressed gas). The development of the BCD/Wing helped to prevent excessive physical exertion in holding neutral buoyancy at depth, but even this advantage can be inadvertently defeated if the wetsuit diver improperly uses too much lead weight along with poor hydrodynamic trim & propulsion techniques.

 

[scubafanatic]

True story, if you are using your drysuit as a BCD. I dive every year with a very accomplished diver who uses no BCD and usually no wetsuit. He still has to swim to maintain depth with a full tank. I suppose a person has enough lung capacity to offset the air in the tank and the wetsuit compression but it would be uncomfortable to change my lung level that far over the course of a dive. Especially with the tank sizes that we use today. 100 cf is 8lb and we use that much out of a 120 or 130cf tank. Add a little wetsuit compression to that early in the dive and you will have a 10-12 pound swing between the start of a dive at 100 feet and the safety stop at 15 feet. That's more or less a gallon and a half of lung capacity. I'd like to dive with someone who can drop down with a 120 and a wetsuit to 100 feet and hold still and hold off the bottom and then use up the tank and hold a safety stop without swimming downward.

well, if you were a 'real man' you'd be able to do that while also running VPlanner on your abacus!

 

[dumpsterDiver]

If you have a small tank and very little wetsuit, then you don't need to put much air in your BC and you can dive without one without too much trouble. However, it is not really safe, especially if you dive with a buddy. In an emergency, a BC will be invaluable. I would hate to have a bad outcome in an accident and know that I could have done more (in a rescue scenario) -if I were wearing a BC.

If you are solo, shallow, warm water (and probably carrying some ditchable lead) then it's not a big deal.

What many warm water people fail to realize is the magnitude of the huge shifts in buoyancy associated with a double layer 7 mm suit, and say maybe a 120 cu-ft or more capacity tank(s). If you are going to pull yourself down and up an anchor line, or crawl up and down a slope, it can be done, but it is not safe, it is not efficient and not something I would choose to do. The swings in buoyancy can be over 25 lbs! This is not something you can swim up or deal with using lung volume manipulation.

I agree that many people wear more lead than they should, however I worry much more about people who carry a lot of non-ditchable ballast and a wetsuit - rather than someone who simply chooses to be over-weighted and wears an extra 8 or 10 lbs in order to deal with a strong current or something (assuming they can ditch all or some of it in an emergency).

Sometimes, I dive without a BC

 

[scubafanatic]

As someone who does most of my dives without a BC or wing and just ether a plate or plastic backpack, proper weighting is almost as important to me as air in my tanks. So when I am watching other people dive (buddies) or reading on the forum, it seems to me that a lot of people over-weight themselves and rely solely on adding air to their BC to achieve neutral buoyancy. I was taught not to rely on my BC but proper weighting and the BC for slight adjustments at depth. That way, if your BC goes tits up you can still swim up with minimal effort.

Why isn't more time spent on proper buoyancy?

Why is proper buoyancy control a separate cert? (To me thats like getting a drivers licence and then having to get a separate endorsement to use the brakes.)

Or am I out of my head? (DON'T answer that question!)

An experienced/seasoned diver thinks/dives as you were taught, inexperienced/infrequent divers tend to rely on the brute-force approach (over weight and use BC to correct the over weighting) because it's takes a bit of effort to record/remember the proper weighting to use, especially if one uses different size/type tanks and different thickness wetsuits over different dives.

 

[BoltSnap]

You just have to be a really good diver.

How does being a "really good diver" help in this scenario? Is fighting to stay above bottom and working hard on breathing, etc. to overcome the added negative buoyancy a sign of a "really good diver"?

It maybe "doable" and the diver can make it through the dive without a BC, but this isn't fun diving and it takes away from the enjoyment of the dive. Old divers did it in the past when they didn't have BC's doesn't mean that it was a good thing, not more so than cave man not having wheels or modern medical care, they survived it but it wasn't good fun.

 

[BRT]

How does being a "really good diver" help in this scenario? Is fighting to stay above bottom and working hard on breathing, etc. to overcome the added negative buoyancy a sign of a "really good diver"?

It maybe "doable" and the diver can make it through the dive without a BC, but this isn't fun diving and it takes away from the enjoyment of the dive. Old divers did it in the past when they didn't have BC's doesn't mean that it was a good thing, not more so than cave man not having wheels or modern medical care, they survived it but it wasn't good fun.

Check back in the posts. I'm just laughing at those who think "good divers" somehow magically defeat physics. Sillyness.