Weight distribution with changing gear configurations

[boulderjohn]

As I read your post, you are diving in fresh water using a 3/2 wetsuit and using steel 95 or aluminum 80 tanks, and you are wondering hot to distribute your 20 pounds of lead. If I have that right, then I am going to concur strongly with those suggesting you are overweighted.

If I were diving in freshwater with that kind of wetsuit and carrying no weight whatsoever, I would be overweighted with a steel 95, and I might need a couple pounds with an AL 80.

Teaching classes in a freshwater pool and wearing a 3mm full suit and using an AL80, I wore 8 pounds because I wanted to be able to descend quickly in case of a problem. I think 2 pounds would have been perfect weighting.

 

[lowwall]

I find it difficult to get weighting right as you get in the water. My trick is to get close and at the end of the dive, dive again. Just as you are getting out of the water get neutral just below the surface. Don't add any air and get out of the water. Now look at the wing/BC and see how much air is actually in it. There should be very little. If there is a lot of air, you have too much lead. A pint's a pound. How many pints of excess air are in there.

It's simpler and more accurate to fully dump during your safety stop. You should be just slightly negative after a moderate inhale assuming you haven't breathed the tank dry. If not, adjust the weighting on your next dive and try again.

More accurate because not everyone can get all of the air out of their BCD/wing underwater either because of the bladder design or the divers' technique. Even if you can squeeze it out on the boat, you still need to account for it while under.

 

[Nemrod]

Interesting setup with the octo on a breakaway necklace bungee. Does it normally run under your arm? Also, why the crossed straps on the VDH plate - is that set up for an actual double hose reg?


This is the key. Even if all our equipment matches, we won't have the same weight needs. The buoyancy of naked people can easily vary 10 pounds, more for the really obese.

FWIW, the density of fatty tissues is around .9 g/cc and non-fatty tissues (primarily muscle and bone) is 1.1. It looks like you'd sink unless you were 50% fat, but you need to add in the approximately 5 pounds lift from the air left in our lungs even after an exhale.

Side bar 1 . My wife uses a conventional set up and her Legend octo is routed under her arm on a 36 inch hose with a 90 degree swivel. It is over her arm in that photo because we had just done a drill for the first dive of the trip and she had not yet stowed it away. The fisherman knot in the necklace does not go under the mouthpiece retainer and easily pulls free for deployment and does place the octo in the so called Golden Triangle ( I had just taken her octo and now she is about to take my primary). And sometimes I have to remind her to stow her equipment, I cannot do everything, lol. And that photo I was just testing my exposure settings and strobes.

Side bar 2 . The VDH plate is universal style and equally suitable for sh or dh regulators. The straps cross because it helps to center and stabilize the plate on the body and helps to keep the straps from falling off the shoulders in use. It has long been acceptable to cross straps even on standard doubles plates, especially for women and smaller divers. Some copies of the VDH plate and similar plates like the Freedom Plate do not cross straps though I guess one could if wanted.

James

 

[lowwall]

As I read your post, you are diving in fresh water using a 3/2 wetsuit and using steel 95 or aluminum 80 tanks, and you are wondering hot to distribute your 20 pounds of lead. If I have that right, then I am going to concur strongly with those suggesting you are overweighted.

I suspect 20 is a bit much, but it's possible he's not that far off. He posted his youtube channel before and we can see that (like a lot of us) he's not exactly svelte:

 

[lowwall]

Side bar 1 . My wife uses a conventional set up and her Legend octo is routed under her arm on a 36 inch hose. It is over her arm in that photo because we had just done a drill for the first dive of the trip and she had not yet stowed it away. The fisherman knot in the necklace does not go under the mouthpiece retainer and easily pulls free for deployment and does place the octo in the so called Golden Triangle ( I had just taken her octo and now she is about to take my primary). And sometimes I have to remind her to stow her equipment, I cannot do everything, lol. And that photo I was just testing my exposure settings and strobes.

Side bar 2 . The VDH plate is universal style and equally suitable for sh or dh regulators. The straps cross because it helps to center and stabilize the plate on the body and helps to keep the straps from falling off the shoulders in use. It has long been acceptable to cross straps even on standard doubles plates, especially for women and smaller divers. Some copies of the VDH plate and similar plates like the Freedom Plate do not cross straps though I guess one could if wanted.

James

Thanks for the info. Since I'm asking, the bolt snap on the octo hose is to keep things in order topside? I'm also wondering why her compass and dive computers are facing opposite directions. Not enough room to work the buttons? Magnetic interference?

 

[Nemrod]

Thanks for the info. Since I'm asking, the bolt snap on the octo hose is to keep things in order topside? I'm also wondering why her compass and dive computers are facing opposite directions. Not enough room to work the buttons? Magnetic interference?

Side bar 3 . Yes, the bolt snap on her octo is so that she does not drag it through sand, across the deck, bang it on the seat/rack and otherwise destroy her pretty regulator.

The blue band goes to a watch, we are old fashioned. The two computers are flipped, one is primary and the other is back up. She does not need to see but the primary computer unless it fails, so she normally flips the backup under (her arms are kinda little). She only has a tiny watch band compass because she has me and I never, ever, never, get lost, ha!

James

 

[broncobowsher]

It's simpler and more accurate to fully dump during your safety stop. You should be just slightly negative after a moderate inhale assuming you haven't breathed the tank dry. If not, adjust the weighting on your next dive and try again.

More accurate because not everyone can get all of the air out of their BCD/wing underwater either because of the bladder design or the divers' technique. Even if you can squeeze it out on the boat, you still need to account for it while under.

I was working on getting rid of that excess air from poor venting. Improving the venting technique will reduce the amount of lead you dive with. If you exit the water in a neutral/negative condition but there is a large amount of air still in the wing, why is there so much air in there? If you have a 32 pound wing, but always keep 12 pounds of air lift in there to be neutral, you only have a 20 pound wing left. And if something happens and you loose that 12 pounds of always there lift, you are now suddenly 12 pounds more negative than you thought you ever would be.

 

[Cthippo]

Thank you for the feedback, everyone.

My actual configuration right now is the 3/2 wetsuit with a steel 72, and occasionally just an AL80 for short dives where mobility is paramount. If my "permanent" regs ever come back from being serviced (over a month waiting on parts now) I will be diving with both tanks in a full redundant configuration.

I've got an AL80 I was given, but it needs a hydro and eddy current inspection and the valve replaced, and so far I just haven't convinced myself that is a worthwhile expenditure. I'd rather wait and spend the money on a pair of steel 120s than an AL tank that offers minimal improvement over what i have now and may introduce buoyancy problems.

I'll keep playing with weight and see how low I can go and still be able to sink

 

[Nemrod]

I've got an AL80 I was given, but it needs a hydro and eddy current inspection and the valve replaced, and so far I just haven't convinced myself that is a worthwhile expenditure.

It is not worth the effort if the cylinder is 6351 alloy and if it is 6061 it does not require Eddy current inspection. Many shops will not fill cylinders that are older than 20 years much less a 6351 alloy cylinder regardless of what inspection was completed. I know, I know, just saying.

James

 

[tursiops]

I've got an AL80 I was given, but it needs a hydro and eddy current inspection and the valve replaced

If it actually "needs" an eddy current inspection, that means it is a 6051 tank and it is only scrap metal. If it is just old and some dive shop told you it needs an eddy current test because it is old, find a new dive shop.