I haven't seen this discussed before and started thinking about this as I'm getting ready to go dive somewhere warm next week. I got a pair of Dive Rite Stainless Steel XT Lite backplates for our upcoming trip for my wife and me. Our last time diving in warm water we either needed no weight, or in my wife's case, was overweighted with our usual steel backplates. Old backplates just under 6 lbs, lite backplates 2.5 lbs, same material (316 stainless). The lite backplate is thinner and has lots of cutouts. The old Dive Rite aluminum backplates weighed essentially the same as the new stainless ones, but are thicker and don't have all the cutouts and obviously are made of a less dense metal
On dry land, 2.5 lbs of lead, 2.5 lbs of stainless steel and 2.5 lbs of aluminum weigh the same amount. In the water, it's all about displacement, and an aluminum backplate will displace slightly more water than a steel backplate of the same weight. I'm guessing it's pretty insignificant. My question - if I take 3.5 lbs off my steel backplate (going from a 6 lb steel backplate to a 2.5 lb steel backplate), will 3.5 lbs more lead keep me at the same buoyancy? Or do I need a little more lead? And would need even a little more lead if I had gone with an aluminum backplate weighing the same as the lightweight steel backplate?
On dry land, 2.5 lbs of lead, 2.5 lbs of stainless steel and 2.5 lbs of aluminum weigh the same amount. In the water, it's all about displacement, and an aluminum backplate will displace slightly more water than a steel backplate of the same weight. I'm guessing it's pretty insignificant. My question - if I take 3.5 lbs off my steel backplate (going from a 6 lb steel backplate to a 2.5 lb steel backplate), will 3.5 lbs more lead keep me at the same buoyancy? Or do I need a little more lead? And would need even a little more lead if I had gone with an aluminum backplate weighing the same as the lightweight steel backplate?