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Very interesting discussion, but it brings to mind the old saying "Measure with a micrometer, and cut with an ax." The concept of super accurate and precise weighting for a SS at 15' or some other depth might come into play if you are diving at your local spot and using all of your own gear, including weights. However, that degree of precision has little to do with the reality of doing dives across the world with a wide variety of different dive ops, as well as the variance in available weights and accuracy of the weights themselves. For example, I have commercially purchased 2, 3, 4, and 5 pound weights, plus a bunch of homemade ones, none of which weigh exactly as stamped. So, if I grab four 4# weights on the dive boat, depending on the variations in actual weight, I could easily be a pound or so over or under what I actually think I have. And then the dive boat may not have the exact poundage I really want, so wind up using a couple pounds more than I think is ideal. Personally, I have never had a problem carrying an extra 2-3 pounds, and far prefer that than to risk corking to the surface at a time and place that is not of my choosing.
*Most of the time I surface with more than 1,000 PSI on a dive (aluminum 80), so I need to take that into consideration about how I felt about the weighting on a particular dive. That's what, 2 pounds in an AL80? It's a small amount, but if I've diving with 4 pounds of lead (plus whatever weight from my regulator, fins, camera, etc.) and I felt fine in terms of buoyancy, should I actually be adding 2 pounds of lead to account for a lighter tank?
If you are at 15' at 1000# with an empty BC, then adding 2# for the rest of the air would work. This should be done using your basic kit. Then you should check the buoyancy of the camera, or any other dive specific gear that could be lost on a dive, a couple of pounds could be made up by breathing technique, but larger amounts cannot. So don't subtract the 10# hammer and chisel to liberate a porthole from your weightbelt because you might lose it and blow through the safety stop or worse yet, if needed, a deco stop. Bob
I'm inclined to add up the total amount of the kit because it represents the total weight I need. I'm simply viewing it as, of the total weight I need for proper buoyancy, X amount comes from lead weights.
Btw, how would you define being overweighted? Is it a number (absolute or percentage) or it is the impact it has on the diving?
I weight my self for the bottom because that's where you are the longest. I swim down so being light at the surface is NBD to me and I don't have problems at the safety stop. I also dive steel tanks to the weight swing to positive is less with an empty tank. The biggest thing is being comfortable on your dive, because it's your dive.
I don't know where this talk about weighting for the safety stop at the end of the dive comes from. This means that the last 15 ft of every dive involve an uncontrolled ascent, which is something you want to avoid.
Of COURSE you want to be weighted right for the 15 ft stop but also at 10ft and 5ft or even 2ft. Cutting back on the couple of pounds of weight it takes to maintain control throughout the *entire* dive from surface to surface is like having breaks on your car that stop at some point AFTER the stop sign. Someone said above that the perfect weight was with 500# in the tank. What if the diver gets delayed and he has 300# in the tank? Cutting the margin so thin will mean that he will not be able to hold his safety stop if he has to use any of the reserve air he has...... think about what you're saying here.
Anyway, I think this is wrong thinking. Obviously we are dealing here with two different paradigms but I think the difference in how much weight you need to be in control all the way to the surface isn't worth the potential issues involved in making an uncontrolled ascent through the last 15ft of every dive. Seriously.
If you think about it, no technical diver on the planet would weight themselves to make an uncontrolled ascent over the last 15ft of every dive for obvious safety reasons so why are you recommending for recreational divers to do just that? It's bad advice if you ask me.
R..