Adjusting Weights

[Splitlip]

It still amazes me how much difficulty divers, especially new divers, have with weights and buoyancy. The certifying agencies seem to be doing a poor job of training.

The BC, in my opinion has become the great enabler and instructors I guess don't spend the time here they should.
I did my BOW without a BC in 1973. By default you had to have your ballast right so you could dive and return to the surface.
When I did my AOW 25 plus years later with a BC, my instuctor over loaded me by almost 100% of what I needed, I presume now to keep me on the bottom when he needed me there. He never offered that I should shed the weight. Did that on my own.

 

[spectrum]

I did my BOW without a BC in 1973. By default you had to have your ballast right so you could dive and return to the surface.

Few divers of that period were diving cylinders with such a mass range through the dive as most do today. Using 50 CF out of a 65 CF cylinder only swings you 4 pounds. Also divers of that era seldom made such dives wearing 14mm of neoprene on their core. As you said getting the weight just right let you return to the surface at the end of the dive. Divers of that era had to be strong swimmers in case they needed to surface early and to manage the rig on the surface. Then came the horsecollar and the BC began to evolve. It is a fun way to dive. Some would even carry a stone to keep them down for the dive and release it in order to become positive.

Here is an intersting thread on the topic:
http://www.scubaboard.com/showthread.php?t=76043&highlight=vintage

Pete

 

[Splitlip]

Dead onn Spectrum. I used a steel 72 and beaver tail jacket most of the time. Sometimes used a the pants too, but ended up with a snorkle vest too to help at the surface.
My point though. I am in South Florida. Most over weighted students are diving with shorties, skins or nothing.

 

[spectrum]

My point though. I am in South Florida. Most over weighted students are diving with shorties, skins or nothing.

That is sad, and way too common.

 

[Green_Manelishi]

Determining correct weighting takes time and effort.
It also takes being comfortable and relaxed in the water or you might "need" more weight than you actually do need.
I use a 4# weightbelt in salt water and could probably shed another pound or so but I don't own any 1# weights. Love it.

 

[jbd]

Proper weighting assumes even more importance as the desirability of slower ascent rates, especially in the last 20 feet before surfacing, becomes a more common practice. It is at this point in the dive when a diver and gear weigh the least while the force of bouayncy is greatest; underweighting makes ascent control difficult and potentially exhausting, overweighting simply more difficult.

I've probably said this a dozen times on this board, but a diver with all gear must be at least minimally weighted - neutral just beneath the surface, with a near-empty tank and empty BC, and breathing normally.

Overweighting requires air in the diver's BC to compensate for the excess lead weight and leads to difficulty in dumping air from a BC while trying to control an ascent. 10 pounds of unnecessary lead causes a diver neutral at 10 feet to be 3 pounds positive at the surface. While 3 pounds doesn't sound like a lot and a skilled diver diver knows how to compensate quickly for this with his lungs, it's a substantial push toward the surface for the novice.

I know you have been saying this for a few years now Don. I wonder why so many people, and most importantly instructors, have so much difficulty grasping this concept?

 

[phhappy]

http://www.scubadiving.com/training/specialty_and_advanced/perfect_buoyancy_on_every_dive/

http://www.divernet.com/technique/0604buoyancy.shtml

Here are a couple articles on buoyancy, and you can find some other related articles from the above two sites too. I am a newly certified OW in June and AOW in Sept. I used to have the same problem. Everytime when I wanted to go down to follow my buddy, I would go up instead. Later I found that it was because I was too anxious, eager, and worried that I might loss him. I would unintentionally taking in more air to make myself more buoyant. So I went up instead. Maybe after you have properly weighted yourself at the decompression depth 5 meter with 500 psi in your tank as suggested, you can try to become more aware of your own breathing control. It makes a big difference in buoyancy. May be you can take on of those Peaking Buoyancy Courses. As a newbie myself, if you really going to keep diving as one of your lifetime hobby and sport. Please consider getting your own equipments. It makes a big difference and will give you more confidence. Before you buy any equipement, do a lot of research and test it out ( if possible) before buying. I made quite a few mistakes myself. A fin that gives me cramp and a computer watch that is too small that I can bearly read (due to my old age). Don't worry too much. Do more dives in swallow water with a reliable buddy. Improve your skill and confident before moving into deeper water. I am sure things will turn for the better in times.

Happy and Safe Diving.

 

[Jeff Toorish]

Just in case no one has mentioned it, there are specialty courses on Buoyancy that can be helpful. SSI and PADI both offer peak performance buoyancy specialties. A peak course may be required for AOW by some agencies. And while a lot of specialty courses are really pretty worthless, a course focusing strictly on buoyancy with a good instructor does have merit.

I skimmed through this thread, but I read most of what Pete was saying and I agree with him completely. On the tank issue, I purchased several 'neutral AL 80s.' They aren't realy neutral when low, but they are certainly closer that the standard 80s and they also allow for a bit more pressure, 3300 psi.

The other thing that is good to remember is buoyancy can change from dive to dive for no apparent reason. It is something that eventually becomes, if not second nature, at least a bit easier.

Jeff

 

[Mark_J]

There seems to be a trend I've noticed where some folks continually look for blame to be assigned in situations like this one and like to point the finger at Instructors. Why is there this mindset that says a newly certified diver must be able to dive like Cousteau himself and the inability to do so is the Instructor's fault?

I remember when I first got my Drivers License, it was a written test followed by a drive around the block and one shot at parallel parking. That was all there was too it and I was a licensed driver. While I knew the fundamentals from the test I had no clue what I was doing so I took an old pick up truck out to the local gravel pit and proceeded to really learn how to drive. The first hand experiences I learned behind the wheel out there were invaluable. Now certainly if I had Dale Earnhardt Jr. sitting next to me in that pickup truck the lessons I learned would have come much easier, however I still was able to develop my driving skills without him.

The same principal applies to diving, while each one of us could develop and learn new techniques by hiring instructors, we could also develop our skills by putting the time in under the water with a capable partner. There were quite a few replies in this thread offering some sound advice to the thread starter on the weighting issue. My advice would be to read up on the topic of weighting as well as some of the suggestions here and then get to the closest dive location you have available for the sole purpose of refining your weighting techniques and skills. Taking a few dives with a specific purpose such as weighting will go a long way in your enjoyment of diving.

 

[riffdiver]

Hello,
As everyone here can see, I'm new around here. I started to take a diving course at my LDC. SSI course that is. Three sessions in the pool. 5 hours so far. Still have no concept of proper weighing procedure.

I read about Aluminum tanks and Steel tanks. I can understand the concept of being positive at the end of the dive and the need to compensate for that in the beginning of dive. But how do you calculate, or establish you buoyancy in the first place.

Where can I read about it??? Or, can someone give me an advise.

Maybe I chose wrong LDC.