Worthington tanks, weighting etc

[Scott M]

Thanks for the reply's. I will start with the baseline the charts give me and work it both ways to try and get to an ideal weight. I think the best we can do is get close because so many factors can change how much we need at any given time. The D.S. adds another dimension. I am still working on just how much air I need or want in the suit and trying to maintain as little air in the B/C as possible. I think once I come up with a good handle on how much I need to keep me warm with the undergarments I am using i will have a better handle on how much weight to use. Thanks for the guide lines.

 

[ronbeau]

With that in mind, How does someone do the math to determine a starting point when switching to steels.

The best way is to do a weight check in the water. Assuming you are doing the check with a full tank the process is the same.

Change weights until you float at eye level with an empty BC and a full set of lungs and sink when you exhale.

Once you have done that you just need to account for the gas that will be used. Air is .08 pounds/foot³.

As a worst case scenario where you drained the Aluminum 80 to empty the difference would be 77.4 x .08 = 6.192 pounds.

Bringing the cylinder down to 500 PSI would result in a difference of 5.15 pounds (2500 PSI used/3000) = 83.3% used.
.833 x 77.4 = 64.49 feet³ used
64.49 x .08 = 5.15 pounds.

Doing the same calculation for an HP 100

If you drained the HP 100 to empty

99 feet³ x .08 = 7.92 pounds

Leaving 500 PSI in the tank
3442 PSI - 500 PSI = 2942 PSI used
2942/3442 = 85.4% used
.854 x 99 feet³ = 84.6 feet³ used
84.6 x .08 = 6.76 pound difference

Hopefully this helps (as opposed to making it more confusing )

 

[Scott M]

Hopefully this helps (as opposed to making it more confusing )

It could not be any clearer now. I appreciate the effort you put into that. I think what I will do when I get the tanks is go out on the boat with all of my different undergarment combinations and spend some time getting the weighting for each dialed in with the steels. I might dive a tank down to 500 also to compare each combo also.

With a D.S. while floating at eye level should I have any air in the suit? How would I compensate for the air I will add to my suit?

Best Regards

 

[John_B]

jbd once showed me a fairly foolproof method for weighting.

In a pool or other confined water, if you gear up normally with 400-500 psi in a tank and thread a series of hard weights in intervals on a long weight belt or 2" webbing, when you exhale holding onto the weight belt you'll see how much weight comes off the bottom. Formula not required.

You can do something similar in calm open water with a good float and some hard weights individually ziptied to boltsnaps at safety stop depth. I've done this with my own 36# line boltsnapped to a mooring ball with a d-ring tied off at 15' to hold the weightclips. If you put a little thought into it you can rig something up that is surprisingly portable.