how to achieve better buoyancy control?

[IndigoBlue]

I gotta wonder where this stuff comes from.

I put new divers in back plates and it's a monster improvement over a bc. All our classes are done wearing 1/4 inch suits so divers need a significant amount of weight.

When all that weight is piled on the hips it just stands the divers up in the water. You can watch hundreds of students around here on a summer weekend and not a single one will be anywhere near horizontal. They need some of that weight higher up.

The back plate is a big help in developing trim although I'll admit it's possible without. The plate puts 6 pounds of that weight close to the body and up with the bc...exactly where many need the weight to be.

As far as ditchable weight, there's no reason that a recreational diver with a light rig and a buoyant suit needs all their weight to be ditchable. In fact judging by the number of students I've seen pop to the surface, the number of weight pouches I find on the bottom and the number of students without hips that I've seen have weightbelts slide off, I'd even say it's dangerous.

In addition a plate and harness provide a very stable platform for the tank which is what it's really there for.

I am not doubting your ability as an instructor to gauge a students proper weighting, Mike. With or without a backplate on a new diver, and I know few new divers who go into a backplate from the get-go, you have to address the same weighting issues.

What I take exception to is Snowbears rude personal attacks, which seem really inappropriate for her being one of the mods.

The relevant weighting issues are, first, adjusting the total weighting (ditchable and nonditchable) to neutralize the diver with an almost empty tank.

The second issue is dividing that total weighting between ditchable and nonditchable. Normally a minimum ditchable amount would be equal to the weight of the consumable gas, usually 6 lbs for a single tank or 12 lbs for a double tank. And even more, if diving in a thick wetsuit, which compresses with depth and thereby loses buoyancy.

The third issue is then whether you have enough remaining weighing in order to go into a nonditchable rigging, such as trim weights, a backplate, steel tanks, etc.

Somewhere along the line Snowbear misunderstood the issues, and took my reply to Spectre's interjection as an attack on backplates. And maybe you too.

We were talking about adjusting the weighting to improve buoyancy.

Wear a backplate if you want. Just do the math right, first.

 

[H2Andy]

"What I take exception to is Snowbears rude personal attacks, which seem really inappropriate for her being one of the mods."

huh? Snowbear has made no rude comments whatsoever. And what does
she being a moderator have to do with her disagreeing with you?

 

[MXGratefulDiver]

Hmmm ... I didn't read Snowbear's comments as a personal attack either. Perhaps a PM would've been more appropriate than a retort if you took it that way.

FWIW - as I was reminded recently, mods are barred from moderating threads in which they are active participants. In that manner, mods shouldn't have to show any more restraint in presenting their views than anyone else.

... Bob (Grateful Diver)

 

[RiverRat]

Hey Rufous,
I'll give you some insight from a new diver. For me "building" my own BP/W rig helped immensely as it "forced" me to do weight calcs, look at tank specs empty and full etc. etc. etc. I suppose it would have been about the same trying to tune a weight integrated BC as well. The BP/W is a little different as you have to take into consideration the weight of the plate, tank adaptors (sta's), rings etc. and also losing some positive buoyancy by eliminating the padding associated the jacket style BC's.
A document written by FredT here on the board helped greatly as well. Basically how and why to dive neutrally buoyant and how to get there. Of course after taking in all this info as others have stated you need to go out and dive your gear and make adjustments where required. When I first dove my setup I was WAY overweighted by 12#. Even then my trim was flat and I was doing a MILLION times better than what I was doing in my OW dives. I underestimated how streamlined the BP/W setup was and how much positive buoyancy I had from the "old" BC I was using. You mentioned you were diving either "neutral" or "near neutral" before. You need to stay on track there.
I think what really helped me was to make DETAILED logs of each dive while tuning my weighting etc. I now know exactly what gear I had on, water conditions, tank style etc. As I get in more dives in more environments and with different gear configurations I can use this info as sort of a "baseline" for an initial weighting.

 

[Snowbear]

What I take exception to is Snowbears rude personal attacks...

Wow! Disagreed maybe, but there was no attack, personal or otherwise. I've tried to find the rudeness as well and though it's true that I'm a bit biased - can't find that either. You are welcome to PM me with further comments if you'd like.

 

[Uncle Pug]

What I take exception to is Snowbears rude personal attacks, which seem really inappropriate for her being one of the mods.

Karl you were the only who was rude. Here in this post where you say, "...there really are a lot of divers on Scubaboard with a lot of good advice, and then there is you, Snowbear,..."

Now perhaps you were a little persnippity because at the end of her previous post replying to you she included a note to rufous to, "use discretion when it comes to filtering through and putting to use the information you receive."

Perhaps you felt that she was infering that it was your advice in particular that could use filtering.

Perhaps that is what you are calling a "rude personal attack."

Well, you are wrong. That isn't being rude... that is just giving good generalized advice.

Yours was the only rude personal attack.

 

[Taucher]

Here's my tips, not that I know anything, but it helped my wife:

It takes time for things to happen. In other words, if you put a tap of air into your BC you will not immediately rise, especially if you are exhalling at the time. Allow a few seconds to feel the effects of adding air. Same with your breathing. As you take a deep breath, you will rise, just not instantly. When coming up, you'll probably need to dump air faster than you think, especially if you have a thicker wet suit, which will also be decompressing. What really helped my wife, and brought everything into perspective was, believe it or not, a night dive. Seems without the 'big picture", or less visual clues as it may be, she could suddenly "feel" the concept of neutral bouyancy. Weird, but it really improved her control.