My Twin Pst E Series 130s Are Here!

[triton94949]

...how would compensate with those babies on? Bigger wing (if BP/Wing are used)?

The only realistic issue on the wing size is regarding how high out of the water do you want to float when you are on the surface? Underwater, the wing size is not an issue (with a drysuit).

Your weight belt underwater will be significantly lighter with twin tanks, because there is more non-ditchable weight attached to your backplate in the form of the two steel tanks, the manifold, the bands, and the double regulators. My own weight belt consists of 16 lbs for cold salt water deco diving (with my twin 72s -- probably less with these twin 130s).

The gas in the twin tanks is about 16 lbs negatively buoyant (260 cu ft / 80 cu ft x 5 lbs per 80 cu ft = 16 lbs), by coincidence.

Therefore if I ditched my weight belt within the first few minutes of a dive, when the twin tanks were almost completely full, then I would be neutrally buoyant at that moment in time, WITHOUT having to inflate my B/C. That is one indicator of perfect weighting, meaning no extra weight on my weight belt.

At the end of my dive, when my twin tanks are practically empty (rule of thirds of course), then I would be about neutrally buoyant with the weight belt on. This is the absolute definition of perfect weighting. You can tell if you are perfectly weighted at the end of your dive, if your wing is empty, and you are neutrally buoyant still.

Therefore my wing only needs to be able to support 16 lbs underwater near the beginning of the dive, and less as the dive progresses and the compressed gas is exhaled (open circuit) into the open water. Even thought these are huge twin 130 cu ft tanks, underwater, it is not an issue. The trade-off is between ditchable and nonditchable weight, not about wing size.

On the surface, it just depends on how high you want to float out of the water with the wing inflated all the way. 50 lbs should be fine. Some people are more comfortable with 75 lbs or more. That is why there is a market for bigger wings.

With a drysuit, the wing only needs to be able to support the weight belt.

If I were diving warm water and with a 3mm wetsuit, I probalby would not be wearing any weight belt at all. And the wing obviously would not need to be any larger either. Everyone is different, however. Physiology is unique.