Weighting for Stages/Deco Bottles

[PfcAJ]

Learn to side mount! No weights required and your cylinders will be in trim either full or empty. I spend the time to learn good setup. I dive BM doubles and sidemount my stages/deco cylinders. With a good setup your cylinders should look like these (just add BM doubles).

I added a butt plate to provide attachement points further back and I also make use of a "ring bungees" as hard attachement points under my armpits.

What do you think will happen when your tanks are empty?

 

[victorzamora]

And as far as being overweight, I'm cutting down on the cheeseburgers so give me a break.

I said overweighted......but, lol.

Just to clarify, I'm not adding weight to sink, but am considering the scenario where the tanks are almost empty and I need to hold a shallow stop. SM or BM makes no difference.

Jokes aside, how many tanks are you carrying such that at the end of the dive you're positively buoyant but afraid of being excessively overweighted at the end? Air is about 0.075 pounds per cubic foot, so a 10# swing is like 135ft3 of gas. I've very comfortably taken just over 500ft3 of gas on a dive (two mains, two stages, and an AL40 of O2) and have never needed to worry about adding lead or anything else.

You should be neutral at 15ft with all of your tanks as empty as you're willing to dive them with no air in your drysuit or wing(s). Are you adding lead to achieve that?

 

[Michael Guerrero]

Yes. The numbers are above. It is very tank dependent. Some big tanks like the Fabers are very buoyant when empty, some like PST are not.

I think this thread has run its course, probably a dozen posts ago. Thanks for the inputs everyone. Glad to know I was on the right track as to how to weight myself.

Mike

 

[PfcAJ]

Is this really news to so many people?

Light tanks are light. Surprise!

 

[Michael Guerrero]

People often think that "heavy" steel tanks require no weight. I can't tell you how many times I've been asked how nice it is to not wear any lead with my LP85s. I always laugh and tell them that in addition to my SS backplate, I still need 9lbs of lead in my drysuit. Shock is typical.

 

[ajduplessis]

What do you think will happen when your tanks are empty?

They stay in trim as the top cylinders pulls down on the bottom one, that how the setup works. But if you took the time to try and understand things before you just jump in, the "lights" might come on eventualy.

 

[victorzamora]

They stay in trim as the top cylinders pulls down on the bottom one, that how the setup works. But if you took the time to try and understand things before you just jump in, the "lights" might come on eventualy.

I think there's some confusion regarding what "light" means. I think this thread isn't referring to the tanks being in bad trim but creating such positive buoyancy that it prevents a diver from maintaining neutral buoyancy.

My question still remains: if you have to add lead to be properly weighted, then the only thing you have to compensate for is loss of breathing mix weight. How is that a problem?

 

[PfcAJ]

They stay in trim as the top cylinders pulls down on the bottom one, that how the setup works. But if you took the time to try and understand things before you just jump in, the "lights" might come on eventualy.

This thread is about your total overall buoyancy.

If you drain your main tanks, they're going to be lighter than they were when they were full. It doesn't matter if they're on your back or under your armpits. People in this thread are noting that sometimes you need weight to compensate, even with 'heavy steels'.

The he second theme of the thread is if you need additional weight to compensate for the positive buoyancy of stage bottles. I contend that you do not unless you're planning on moving some distance with a bunch (>3 or 4) of stages in a cave.

Get with the program

 

[rjack321]

Intuitively, I feel like the proper thing to do is to weight myself for that occasion. But that means I'll be pushing 60lbs negative at the start of the dive if I'm using a couple stages/deco bottles.

You are carrying almost 800cf of nitrox? 1cf "weighs" 0.0779 lb. Helium is less but that doesn't change your end weighting. So the only way to "60lbs" heavy at the start of the dive is to have 770 cf on you. (60/0.779 = 770)

I would not buy lp120s, forget those water heaters. 95s are plenty big to start and with 1 or MAYBE 2 stages is ample gas for reasonable cave dives for a long time. Get some experience before concluding that you need "more" gas.

---------- Post added October 15th, 2014 at 10:47 PM ----------

People often think that "heavy" steel tanks require no weight. I can't tell you how many times I've been asked how nice it is to not wear any lead with my LP85s. I always laugh and tell them that in addition to my SS backplate, I still need 9lbs of lead in my drysuit. Shock is typical.

I need 20lbs in saltwater and 10lbs in freshwater to be neutral in my cold water suit and lp85s...