Dropping a weight pocket on a line—dumb idea?

[Storker]

What I had in my mind would be that, for example, the BC has failed and the diver is having difficulty maintaining a 15 foot safety stop and is finning furiously and takes out the lift bag and fills it just to the point that it provides enough lift to be neutral or very close to that.

When I've been out of the water for a too long time, and my buoyancy control is... let's say "suboptimal", I've shot a bag from my safety stop. And being a mite negative, it's very easy to keep my depth just holding on to the line up to the bag that's sticking up from the surface.

So if I were moderately negative due to a BCD failure, that method would be pretty obvious to control my buoyancy.

 

[boulderjohn]

I assume this is done at the beginning of the dive, with a single tank, right? If so, is this assuming a five pound shift in buoyancy (i.e. AL80)? Presumably this will make a diver neutral, or very slightly negative, at 15 feet at the end of the dive with 500 psi left in the tank?

It is frequently done at the beginning of the dive, and some people advocate adding additional weight to compensate for expected loss of air during the dive. Some don't agree, saying that at the beginning of a dive, there is enough trapped air in the gear to take care of that.

But let's talk about 5-6 pounds of extra air.

When I instruct an OW pool session, I am usually about 6 pounds overweighted so that I can drop more quickly if needed. When we first go to the deep end of the pool, I do the following demonstration for the students. I dump all air and settle on my knees at the bottom. I add a random shot of air--not a lot. I inhale deeply enough to rise off the bottom, then exhale enough to stop. I inhale and exhale my way to the surface, using only my breathing to ascend--no kicking or adding air. Once my head breaks the surface, I exhale forcefully and begin to sink, using only my breathing to work my way slowly down to the bottom,

I can do that easily while 6 pounds overweighted, so I think mosst divers can get to the surface kicking while 6 pounds overweighted.

 

[aquacat8]

Did you get certified at the Pinnacles? owned by Joe Ford.
He closed that shop down. John his long time employee and right hand man left to buy Marin Diving Center.
I got certified through the Pinnacles in Novato in 1998. I sat in that classroom and used that same pool, small world.

I was a huge ab diver for years. The last few years I tapered off though. I never was able to get a 10”, biggest I ever found was a 9-7/8”.
Ab diving is closed this year, and we figure it will be closed for quite sometime if not indefinitely. The kelp is way down, almost non existent. I do fun dives with Seals Water Sports in Santa Rosa now. It also used to be a Pinnacles owned by Joe. Joe sold it to Scott and Scott renamed it Seal’s. We do abalone feeding and urchin harvest and relocation dives. We’re trying to do what we can to save what abs are left and to give the kelp a fighting chance against voracious grazing urchins.

Yes! I got certified at Pinacles and went Snorking with the North Coast Ab divers before I was certified. My ex boyfriend took abalone, but I mostly went sightseeing. I am so sorry to hear if the decline of the Kelp Forest... heartbreaking! It is fast growing though, unlike coral, so if conditions improve it could come back. Thanks for doing what you can to help.

 

[JamesBon92007]

It is frequently done at the beginning of the dive, and some people advocate adding additional weight to compensate for expected loss of air during the dive. Some don't agree, saying that at the beginning of a dive, there is enough trapped air in the gear to take care of that.

But let's talk about 5-6 pounds of extra air.

When I instruct an OW pool session, I am usually about 6 pounds overweighted so that I can drop more quickly if needed. When we first go to the deep end of the pool, I do the following demonstration for the students. I dump all air and settle on my knees at the bottom. I add a random shot of air--not a lot. I inhale deeply enough to rise off the bottom, then exhale enough to stop. I inhale and exhale my way to the surface, using only my breathing to ascend--no kicking or adding air. Once my head breaks the surface, I exhale forcefully and begin to sink, using only my breathing to work my way slowly down to the bottom,

I can do that easily while 6 pounds overweighted, so I think mosst divers can get to the surface kicking while 6 pounds overweighted.

So, with that "random shot of air" would you say that is perhaps one or two pounds of lift? That sounds like it ends up being very close to how I adjust my weights for diving without a BC--with a new wetsuit or other new buoyancy change I'll make a calculated guess and go diving. During the dive I'll decide if I need a little more or a little less weight and make the adjustment for the next dive. So far that has always been close enough so as long as I don't make any new gear changes then I'm good-to-go. All-in-all, while holding a medium breath, I am about 4-5 pounds negative at the beginning. Since we know that we can also control our buoyancy using or lungs then being a bit negative at the beginning of the dive is not usually an issue, especially diving is such places as Southern California. However, I have not tried diving without a BC is places with delicate reefs and sandy-bottom swim-throughs (or caves) so I'm not absolutely certain that diving without a BC would be a good idea. Around here I don't think anyone cares if you rest a fin top on the sand or a rock and it's very unlikely that anyone's watching. Contrary to what some have stated concerning wetsuit compression I've never experienced a situation where my 1/4" Farmer John lost enough buoyancy that I felt uncomfortable with the situation, or, for that matter, even noticed. Perhaps it's because I dive with an old Rubatex suit and it doesn't compress as much as the more modern, super-stretch suits.

Getting back to the "eye-level" buoyancy check, I was not taught that in my course way-back-when however I do something along the same lines whenever I jump off a dive boat where someone else set up my weights for me. I immediately can tell if I'm too buoyant and I probably am just emptying my lungs to see if I submerge. If not, I usually say something like "necesito mas peso." I may be in trouble if I go to Indonesia.

 

[JamesBon92007]

Yup, I'm in for that one !! (with pics, please! )

That's seems to be a stretch as far as staying "on-topic" goes. I'll take some pics and send them via PM a little later today.

 

[aquacat8]

I just want to thank everyone for all the thoughtful and thought provoking answers to my “dumb idea”... I learned a lot and had some fun, this is what I love about Scubaboard

That's seems to be a stretch as far as staying "on-topic" goes. I'll take some pics and send them via PM a little later today.

I want to see too!

 

[Eric Sedletzky]

Yes! I got certified at Pinacles and went Snorking with the North Coast Ab divers before I was certified. My ex boyfriend took abalone, but I mostly went sightseeing. I am so sorry to hear if the decline of the Kelp Forest... heartbreaking! It is fast growing though, unlike coral, so if conditions improve it could come back. Thanks for doing what you can to help.

You went diving with the North Coast Divers? I started that club, that was my dive club. Holy cow! Really small world.
I can’t tell you if I was there that day, but if you happen to have a group photo I can see.

 

[JamesBon92007]

That's seems to be a stretch as far as staying "on-topic" goes. I'll take some pics and send them via PM a little later today.

@Mark IV Here are some pics and stuff:

$10 Backwing Pictures

 

[JamesBon92007]

I just want to thank everyone for all the thoughtful and thought provoking answers to my “dumb idea”... I learned a lot and had some fun, this is what I love about Scubaboard

I want to see too!

Here ya go!

$10 Backwing Pictures

 

[aquacat8]

You went diving with the North Coast Divers? I started that club, that was my dive club. Holy cow! Really small world.
I can’t tell you if I was there that day, but if you happen to have a group photo I can see.

Oh I’m not sure about a club... Jon from pinnacles invited us. A bunch of his friends would show up. All weather dependent. There were also camp outs and cook outs but I never made it to those... sorry I didn’t now.