FrankT:
OK -HH
Please give me a lesson on how to adjust the SP straps.
Thanks
Frank
The common complaint that people have is that the SP strap has a "too high" camming force. This then makes the SP strap into a nasty bear-trap that bashes knuckles, pinches fingers, causes cursing, etc.
The "lesson" is deceivingly simple, and it is to understand that the SP strap/buckle doesn't have to be anywhere nearly as bear-trap tight as you think it needs to be in order for it to securely hold a tank for a dive.
In other words, if its tight enough to complain about, you probably have it overtightened (overkill).
For me, it was just trial-and-error until I develop a feel for just how "loose" it could be before it might slip. If you're looking for a rule of thumb, I'd say that if you need a strong support to close the buckle (like support in a tank rack), then your strap is "way, way too tight".
What I do is to set the band length and try to close it. If its above, say ~30lbs (a typical tank weight), then its probably too much...I'll stop before I've passed over the top of the camming action. If I can close it but it took a "noticable" effort, then its still probably too tight, so I'll loosen it up and try it again.
After I get the closing force to something "acceptable" (sorry that I'm being vague here), I then pick up the entire rig by the BC handle and give it a couple of shakes.
(BTW, if your BC has one of those loops that go around your tank yoke, use it, because if its going to slip, the loop will show it so).
After you get this "acceptable" strap closing force, try loosening the strap a little bit more, and then pick up the rig and give it another test shake. Keep working it down to see where it finally slips...you'll probably be surprised. Pick some value in the middle (between "accepable" and "slips") that you're comfortable with, and then go try a test dive.
Naturally, what matters is that nothing slips loose, including at the end of a dive, so a dive is always the final, no-BS test. And if you frequently use different diameter tanks, whenever you get to whatever closure force works for you (both above and below), consider marking the belt's D-ring location if you want to minimize the amount of time it takes to adjust it.
FWIW, my strap is now "loose enough" now such that I usually don't need to do anything more than put my heel next to the tank base and my right hand on the tank yoke, reach down and push shut the cam with my left hand on my first try, and I'm not a muscle man...I'm just your typical "office desk job" fitness/strength kinda middle-of-the-road guy.
Finally, a caveat: I only use hard backpack/plate BC's, so I don't know if or how well this applies for soft backpack BC's.
-hh
