Neutral with No Weight

[sambolino44]

I recently posted in the BC and Weights forum, asking about different weight harnesses. My belt is not making me happy, and I had been looking at the possibility of adding weight pockets to my BP/W harness, essentially making it an integrated rig. I already have a lot of my weight on my rig, with a steel cylinder and a weighted steel backplate. I have 4 lbs on my ankles (neoprene drysuit), and 12 lbs on my belt.

Ever since I switched from a jacket-style BC to a BP/W, I have not practiced "doff and don", or taking the rig off at depth. Not that I ever did it that much before, but I have practiced it, and when I accompanied my wife during her cert course my curiosity about it was piqued while they practiced it.

I'm trying to remember exactly what the circumstances were, whether it was with my old wetsuit, my old BC, or what, nor do I remember the depth (I think it was pretty shallow), but I do remember doing a "doff and don" once, and was so positive that I was just hanging vertically straight up after I took my rig off. I was able to get it back on, but what a hassle! I think if I take the weight off my belt and add it to my rig that situation would only get worse, thus the interest in a weight harness.

It occurred to me today, though, that if I let all the air out of my suit (I've never experienced much squeeze discomfort in my stretchy neoprene suit, even at depth, at least no like the shell suit I tried), that I might be able to approach neutral buoyancy with only my ankle weights if I'm deep enough. It would seem that, for every suit, there would be a depth where the suit would be compressed enough to be neutral. Whether that depth is survivable, I don't know.

What do you think? Anybody with experience that my shed some light on this?

 

[nereas]

I think you should always wear a weight belt equal at least to the back gas you will consume.

For a single 80 cu ft tank, this equals 6 lbs.

For twin 105s this equals 12 lbs.

That way you can easily ditch this quickly if you need to, early in your dive, when your tanks are still heavy.

Wearing the rest of your weighting as nonditchable on your backplate is fine. Deep Sea Supply makes weight plates of up to 4 lbs each. I have four of them mounted on my single-tank BPW with an STA.

For my twin tanks, I use a plain 6 lb SS BPW.

I also do not believe you should be practicing ditch and don in the open water. Too dangerous.

 

[LIVES4SHARKS]

Is your weightbelt moving or are your weights moving during your dive? I cinch up my weight belt really tight before getting in the water and I also do one final cinch as I descend if needed. I also have triglides between my weights so they don't move. I only wear a weightbelt if I am diving in SW since I dive a steel BP and steel 120 tank.

Good luck!
Carolyn:shark2:

 

[BlueDevil]

If all you want to do is add some non-ditchable weight to your rig you could consider Brightweights - they have 1.5kg weights that attach to the tank with a weight harness. I have been using them for many years.
BRIGHTWEIGHTS - Swim Like A Fish

 

[String]

Im curious about what the problem is with a belt ? Is it the bulk? Is it the fact it moves or is it unstable?

Obviously wearing it under your crotch strap is a good idea as it'll stop it accidentally jettisoning.

Failing that, have you considered a weight harness as opposed to a belt?

 

[sambolino44]

I think you should always wear a weight belt equal at least to the back gas you will consume.

Sounds good to me.

For a single 80 cu ft tank, this equals 6 lbs.

For twin 105s this equals 12 lbs.

I'm curious how you came up with those numbers. The way I understand it, the American system of identifying tanks uses a number which would be the volume of air at one atmosphere which, when compressed to the working pressure of the tank, will fill it. In other words, if you took a full 80 cu ft tank and used it to fill a balloon, the balloon's volume would be 80 cu ft. I know the numbers are approximate. But since 2 X 105 is 210, and 210 is way more that twice 80, I wonder why the weight for twin 105s is so much less than twice the weight for one 80. At any rate, I'm not really concerned here with how much of my weight is ditchable, nor am I looking to change that. For the record, I use a single HP100 Steel cylinder, so I think, according to your calculations, my ditchable weight is more than the weight of the air I'll consume. But that's not really the point of my post.

That way you can easily ditch this quickly if you need to, early in your dive, when your tanks are still heavy.

Wearing the rest of your weighting as nonditchable on your backplate is fine. Deep Sea Supply makes weight plates of up to 4 lbs each. I have four of them mounted on my single-tank BPW with an STA.

Yeah, I'm pretty sure the ones I have are the 8.1 lb set. I have a DSS rig.

For my twin tanks, I use a plain 6 lb SS BPW.

I also do not believe you should be practicing ditch and don in the open water. Too dangerous.

This bring up an interesting point. Many of the skills which are taught in the classes expose us to an increased risk of injury. Ditch and Don, CESA, Buoyant Ascent, even air sharing practice are all more dangerous than just diving. We are encouraged to practice life-saving skills, but not in open water. My local public pool does not allow SCUBA skills practice except for official SCUBA classes with a certified instructor. It seems like we're between a rock and hard place; either don't practice skills, or sign up for a class every time we want to practice skills. But once again, not really to the point of my post.

Is your weightbelt moving or are your weights moving during your dive? Not really. I cinch up my weight belt really tight before getting in the water and I also do one final cinch as I descend if needed. Yes, that's what I do, too. I also have triglides between my weights so they don't move. Me, too. I only wear a weightbelt if I am diving in SW since I dive a steel BP and steel 120 tank. I enjoy warm water, but I live near cooler water, so I use a drysuit, thus more weight than that.

Good luck!

Thanks for your advice, but it's not really to the point of my post.
Carolyn:shark2:

If all you want to do is add some non-ditchable weight to your rig you could consider Brightweights - they have 1.5kg weights that attach to the tank with a weight harness. I have been using them for many years. Thanks for the suggestion, but I don't know how you got the idea that I want to add non-ditchable weight to my rig.
BRIGHTWEIGHTS - Swim Like A Fish

Im curious about what the problem is with a belt ? Is it the bulk? Is it the fact it moves or is it unstable?

Not really any of those, well maybe the bulk. The belt on my harness fits right above my hips, so there isn't enough room between the bottom of my harness and the top of my hips. If I don't put the belt above my hips it falls off no matter how tight it is. And the tighter it is, the more uncomfortable it is, especially on long beach hikes and long surface swims.

Obviously wearing it under your crotch strap is a good idea as it'll stop it accidentally jettisoning.

I've encountered a lot of experienced divers and instructors who strongly discouraged me from wearing the ditchable weight belt under anything, like the crotch strap. It seems they're more concerned with not being able to ditch easily than the unintended ditch. So I usually put the belt on over the crotch strap. I've tried it both over and under, and it's a real PITA either way. Once again, not really the point of my post.

Failing that, have you considered a weight harness as opposed to a belt?
Well, I mentioned that two times in my post, so the answer is yes.

Well, first I want to thank everyone for the advice and help, but it's a bit frustrating when it seems that nobody understood the point I was trying to make, or the question I was asking. Now that I read my post again, I see that I didn't make it very clear what, exactly, was my point, so I guess I shouldn't complain about the responses.

Since I first posted, I have practiced a Ditch and Don in about 25 FSW with my normal rig and weight. I was pleasantly surprised to learn that I was not nearly as buoyant as I thought I would be. I was floating a little bit, but only just so. I think if I had been only 5 or 10 feet deeper I may have been neutral or negative. That was the whole question: at what depth do you achieve neutral buoyancy, independent of your rig, BC, tank, etc? Obviously this depends on your suit. I was just wondering if anybody would like to share their experiences. I have done a search on "Ditch and Don", but I didn't find much that way.

Thanks again, everybody.

 

[selytch]

I just posted a thread with a problem similar to yours.
And shortly after I used a tool from another thread.
This may be helpful to you too!

http://www.scubaboard.com/forums/ba...y-exercise-troubles-after-switching-rigs.html