Doubles weighing?

[smorneau]

38 lbs of ballast + a LP 95 (~2 lbs )and regulator (~2 lbs) implies your exposure suit 42 lbs positive. That is quite a bit.

Determine how buoyant your suit is and adjust your ballast so you are negative by the weight of your gas (~10 lbs) +2-3 lbs. i.e. a total of about 12 to 13 lbs negative.

If your Kydex plate is appropriate for your ballast requirements there is no need to switch to an aluminum plate. If your suit is even +30 lbs use your SS plate without the weight plates.

Tobin

You had me do a weight check prior to purchasing my single tank rig from you. I was using just my suit with my winter insulation, hood and I needed 40lbs.

Sent from my Nexus S using Tapatalk

 

[Colliam7]

My guess is drop 9 for the tanks (12 for the doubles -3 for 95 you used) And add 5 for the SS plate you were useing, assuming the Kydex (plastic) plate is neutral. May be drop another # or 2 for the extra reg you will be packing. I'd go for 32# total, and be at 15' ahead of time for the check.

I agree - this is a good start. My only (minor) adjustments would be:

1. I would drop a total of 3 pounds for the combined weight of the second reg plus the manifold plus the tank bands.
2. Rather than adding 5 lbs to your waist / weight harness, why not use you SS BP?

Doppler's recommendation of a fish scale is also a good one. If you weigh your single tank rig, then weigh you doubles rig, you would have a good idea of where to start with the weight adjustment.

 

[cool_hardware52]

You had me do a weight check prior to purchasing my single tank rig from you. I was using just my suit with my winter insulation, hood and I needed 40lbs.

Sent from my Nexus S using Tapatalk

If your suit is +40 you need about 42 lbs of thing that don't float.

Tobin

 

[TSandM]

I'm confused about the tanks . . . TDL's cylinder spec chart lists a PST MP72 with a working pressure of 3300, and those are viciously negative (-6 empty). The LP 72s I've come in contact with, that have a psi working pressure, are not like that -- they are actually close to neutral when empty. I think Steve's idea of the fish scale is a really good one, because unless you know how negative your rig really is, you're going to be WAY off on weighting.

 

[ajduplessis]

There is really only one way to calc/dail-in your weight requirement for a setup. Get in the water (with correct gas pressure, is ali are used) and get someone that can help add/remove weights. I do undertsand that you just want to get a feel, but the best feel is in the water!!

This process should not take more than a couple of min and you need no more 5 or 6ft of water. Once you have the weight required dailed in can you start to move it around to optimise your trim. It is extremely easy and very effective.

There is no magic calculation IMO!!! I believe the biggest problem today is that to many divers try and make use of calculations to determine their buoyancy and this is why they struggle with holding stops, high SAC, bad ascent control, kicking reefs and silt to name but a few.