Thought I knew, but

[coldwaterdufus]

now, I'm wondering. I have read the other threads wrs weighting between tanks. They generally talk Al wrs steel. I normally dive cold, drysuit, steel 100's XS 7, lead at 34lbs in salt. Buoyancy empty ( 500 psi ? ) is -2.5 lbs compared to Al 80. ( +4.0 lbs ) I drop 6 lbs compared to Al 80. I get that, I understand the difference. It's all about buoyancy at the end.

I borrowed my buddy's X8 119 steel. I haven't dove it yet. Buoyancy empty is essentially the same as my steel 100, -2.0 lbs. This says I don't drop any weight.

I stood on the scale with each tank. Body weight = 154.9 lbs ( I'm a little guy ). Steel 100 total weight = 197.8 lbs Steel 119 total weight = 210 lbs, a difference of 12.2 lbs more with the 119.

Question is this. Buoyancy says I don't drop any weight, but I'm 12.2 lbs heavier going in. This seems to be very heavy going in and I still can't drop any weight ???? I think I'm missing something somewhere.

Thanks ahead of time for any explanations. I copied the following info. to show basically no difference between the steel 100 and the 120 on the chart . (essentially the same 119 vs 120)

3. Estimating weights changes due to tank/cylinder type:

We can choose to dive with tanks made of Aluminum (AL) OR Steel (ST), and in various volumes. Different tank types float differently. We want to be able to stay neutrally buoyant especially at the end of the dive, when our tanks are emptied and lighter.​

Cylinder type and volume	Weight change
AL80	+ 4.4lbs/ 2kg
AL100	+3.0lbs/1.4kg
St HP80	-2.5lbs/1.1kg
St HP100	-1.0lbs/0.5kg
St HP120	0

 

[The Chairman]

Some tanks are just stinking heavy out of the water, but their in water characteristics aren't all that bad. The actual volume of the tank plays a huge part in this.

 

[GillScales]

Think volume and density, not weight.

 

[Linedog]

I had the same issue when I switched from steel HP100's to steel HP130's. The 130's weigh more on land but have close to the same buoyancy as the 100's in the water.

 

[Shftrdog]

The volume is greater in the 119