NOR-CAL DIVE EMT:
Hey Everyone. I am looking at getting my first bp/w setup. I am been looking at a few different brands and I am have seen some minor variances such as angle and height (I'm 6ft 3in). Certain companies offer more than one size (DSS) and others do not. If someone could point me in the correct direction, it would be appreciated. Thanks
Hi Nor-Cal,
To realy understand backplates one needs a historical perspective. Backplates originally developed to mount heavy double steel tanks, and then adapted for use with singles.
What is little understood or recognized is that backplates fit you differently when using singles vs doubles. With double tanks, the tanks are very close to the divers back, essentially seperated from the diver by the thickness of the plate.
In many cases the lower corners of the plate don't even touch the divers back because the tanks first hit you in the butt.
This is not the case when using a backplate with a single tank. Singles are spaced away from the divers back, and the lower corners of the plate will contact the divers back. That's why you see the "extra bends" on the lower corners of many plates.
A flatter overall bend, and large radius corners keeps a plate from digging into the divers back, that the approach we take. In addition a flatter plate with a shallower center channel will move a single tank closer to the diver.
The practical limit to how flat one can make a plate, and how shallow the center channel can be is the need to be to accomodate double tanks, which mount via bolts though the center channel. Our plates accomodate doubles, and our low profile delrin thumbwheels reduce interference wih exposure suits.
Most backplates are stamped. Stamping dies are vey expensive, and each size requires at least two dies, a blanking die and a piercing die. This makes offering multiple sizes very expensive for most. The typical "one size fits all" plate is usually just under 16" tall, because the material is most often purchased in 48" widths.
We don't stamp our plates, we cut them with a programmable abrasive waterjet. That means different size plates are a program change, not a pair of new dies. Waterjet cutting is much slower and more expensive than stamping, but the flexibility it offers is worth the trade off to us.
Having said that, I'd guess that most "one size fits all plates" would be fine height wise for you at 6'3". If your plate is too long it can land on your hips (ouch) and limit your ability to arch your back. If your plate is too short the waist strap will be too high, riding across your rib cage, instead of just below it.
Regards,
Tobin
