I dropped 6 lbs. yesterday!!

[jeanne001]

Of lead weight that is. I normally wear 12 lbs. with a 7 mm wet suit, dive skin, 7 mm hooded vest and a steel 80 tank (I weight 140 lbs.). I had mentioned this fact to a group I was talking with and I thought they were going to pop a blood vessel. We were getting ready for our next dive and they told me to drop 6 lbs, right now. Four of them came over and started examining my weight dispersment. After 5 min. we were on our way and I was a little nervous. I did a weight check and I couldn't believe it, I was right on!

I had tried this a week ago (although then I tried to go to 10 #) and I thought I was too light. I don't know what happened between then and now but I am really happy about it. Wow, it is so freeing not having to carry around all that weight. I wonder what I will be able to get to when I can shed the skin and hooded vest?

Jeanne

 

[Charlie99]

If you have a loss of BCD buoyancy again, you will find it much easier to stay on the surface. http://www.scubaboard.com/forums/basic-scuba-discussions/239364-i-am-disappointed-myself.html

I normally wear 12 lbs. with a 7 mm wet suit, dive skin, 7 mm hooded vest and a steel 80 tank ..they told me to drop 6 lbs...... I did a weight check and I couldn't believe it, I was right on!

I had tried this a week ago (although then I tried to go to 10 #) and I thought I was too light. I don't know what happened between then and now but I am really happy about it.

The most common reasons for a diver thinking they need more weight than they really do is 1) unconsciously finning upward or treading water, and 2) sucking in a big breath of air before trying to descend (Unlike when swimming, in scuba you should strongly exhale when you want to submerge).

I wonder what I will be able to get to when I can shed the skin and hooded vest?

At some point you will be overweighted without any lead. At that point you need to change tanks to something that doesn't have as much negative buoyancy as the particular type of steel 80 you are using. Some steel 80's are 13 pounds negative when full, 7 pounds negative when empty.

 

[jeanne001]

At some point you will be overweighted without any lead. At that point you need to change tanks to something that doesn't have as much negative buoyancy as the particular type of steel 80 you are using. Some steel 80's are 13 pounds negative when full, 7 pounds negative when empty.

Does this mean at some point I may have to go to an aluminum tank?

 

[Charlie99]

Does this mean at some point I may have to go to an aluminum tank?

If you get rid of enough neoprene to lose 6 pounds of bouyancy, then to keep from being overweighted, you will need to use a tank with less negative buoyancy. It could simply mean moving from a faber steel 80 with -7.22 pounds of empty buoyancy to a PST tank that is less negatively buoyant. The key tank specification that affects weighting is the "Buoyancy Empty, lbs (w/valve)" column in a table of tank specs such as Scuba Cylinder Specification Chart . Some of the PST steel 80's have only 1 pound of negative buoyancy when empty.


Getting rid of the dive skin has negligible affect on your buoyancy, and getting rid of the hooded vest is probably only a couple of pounds at most. Using no wetsuit at all, or going to a 3mm wetsuit would have a much bigger difference and then you might need to look at other tanks. Conveniently, if you head off to some tropical resort where you'll be wearing a lot less neoprene, your rental tank will most likely be an AL80, with 4 pounds of positive buoyancy when empty.

 

[spectrum]

jeanne001

First off I am asuming that you did not crossover from salt to fresh water, since that would have a similar effect.

Other than that you probably just crossed a line in comfort and technique and down you went!

It's hard to say if you will run out of buoyancy margin with that cylinder. Did you get to challenge that new found weighting with a near empty (500 PSI) tank in the shallows? Do you know what brand/model the cylinder is? It would be intersting to know if it'a one of the ultra-negative ones.

My Bare chicken vest, 3mm torso & 5mm hood is abut 3.5 buoyant in an XL.

Pete

 

[charlesml3]

Wow, if you were six pounds over that must have been some miserable diving. You must have been keeping a lot of air in your BC to maintain neutral. I bet that was a pain on a multi-level dive.

Every time I think "OK that's it. I can't drop any more weight and stay neutral" I wind up being wrong. This past week in Belize I dropped another pound. I'm only taking 4 pounds of lead now.

-Charles

 

[jeanne001]

How do I find what brand/model of tank I have? Is it stamped on the tank somewhere? I bought it as part of a package. It makes no difference buoyancy wise if I'm at 3800 or 500 PSI. It is the same.

 

[hudson]

Jeanne,

I would make absolutely sure you are ok with 6lbs. Buoyancy is not the same at 3800 or 500 psi. You should test your buoyancy with 500psi or less in the tank, and when you are comfortably neutral just below surface, add 1lbs for good measure & safety.

The reason is, 6lbs is a very low number with 7mm wetsuit + vest, unless they are really old and lost most insulation. I'm not saying it's impossible, but it's probably the minimum anyone can ever get away with. With a very similar configuration and I would need 11lbs. And that's in fresh water. I'm also negatively buoyant - without a full breath and no equipment on, I sink.

 

[jeanne001]

I found out that I have an XS Scuba HP Steel 80 tank. the spec sheet says that the tank is buoyancy full is -9 lbs.; buoyancy empty is -3 lbs.; and the empty weight is 27.7 lbs.. so how does this info change things for me?

I never have a problem at 20' maintaining my buoyancy. It has always been hard for me about the 10' mark up to the surface. I'm never sure if this is a weighting issue or if it is just me getting my buoyancy down. I DO NOT have buoyancy issues at any other time either. I did add 2 lbs. this past weekend because I got nervous about it. My last dive was for 47 min. (60'/30 min. & 20'/17 min.) and PSI was 3660/1540, again 10' and up it is hard for me. My wet suit was new last sept. I am in fresh water. I am 5' 1" tall and 140 lbs. (Yeah, I know I know.)

What do ya think?

 

[MauiScubaSteve]

The important parts you mentioned are -3 lbs. empty and fresh water. An important part you didn't mention is how tall you are. If you were 5', 140 lbs, you would not sink as easily as if you are 6', 140 lbs.

If you go on an ocean diving trip, where temps are similar so you wear the same rubber, your likely AL 80 rental tank and salt water buoyancy will bring the weight required up significantly.