The VDH plate was designed out of aluminum to be intentionally light weight for traveling. A stainless plate would actually be heavier. All those cut outs would be for weight mitigation, but it adds to the production cost, and would not be as light
The 16 gauge stainless is approximately 0.062inches thick. That is a fairly flexible plate. They are adding a lot of stiffness in the vertical axis (to support the shoulder straps) with the bends (contour) on the plate.
In the “technical details” it says:
• 10.5″ (26.7cm)(widest point) x 15″ (39.4cm)
• 1.25″ (3.2cm) depth (with contour)
That 1.25” of depth due to the contour would translate into an extra 1.25 inches of water column increase in cracking effort.
The VDH plate is intentionally flat to keep the cylinder (and regulator) as close to the diver as possible.
As Bryan mentions, the plate itself is only about 1.3 pounds. My complete backplate kit is about 5 pounds, but that includes the harness, the wing, the SS waist buckle, and all the hardware (including SS sliders and D rings).
The VDH plate is thicker, but that is part of the advantage of designing with aluminum. I have designed many structures out of steel and aluminum. When it comes to weight reduction, aluminum will outperform steel. And yes, I have done structural comparisons with some exotic alloys (of steel, aluminum, etc.). There are many other tradeoffs were steels and stainless steels are better, but not for weight.
Buceador con escafandra autónoma clásica.