paulwlee once bubbled...
It seems to me that in the context of recreational diving they are similar. The backplate-harness-wings seems to be the best solution for diving doubles and hanging two AL80 stage bottles etc, and this is where they are 'proven'.
But in single tank recreational diving, the claim that they bring many benefits over conventionally used (and thus widely tested) BC's makes it similar to the claim that split fins are better, etc.
Just my 2 cents' worth.
Just back from 2 weeks of diving...
Yes, this is basically my point. If I had to refine it further, I'd say that it consists of two basic elements:
The first element is to what degree any benefit is Real. Most Engineers will tell you that if you can't measure it, it doesn't exist, and if you don't have objective performance data, all you have is an opinion.
When I've commented on "Snake Oil" products, its because these marketeers either don't have any data whatsoever, or the data that they have is invalid because it is profoundly flawed (specific examples upon request).
The problem here with BP/Wings is that nobody has the objective engineering data to prove it...at best, we have anecdotal experience. This doesn't mean that the claim is wrong: its simply unquantified.
BTW, I do agree that dragging a set of gear alone through the water is the wrong test: you need to test the gear's streamlining with it configured onto a "person".
The second element is even if the benefit is real, we need to test it further: is it also significant?
(Edit: this is the "so what?" factor: a changel not of sufficient significance is not worth the effort of its adoption).
As this applies here, what may be significant enough to justify it for technical diving may not necessarily still be significant when applied to recreational diving.
For an analogy, a good comparison to dive gear streamlining might be a car's fuel efficiency (MPG). Good fuel economy is definitely important under some circumstances (such as some NASCAR races), but for most of us, we don't get excited if we found a way to get 27.5mpg instead of 27.0mpg(*), if we track our automobile's MPG at all. Because gas is cheap and there's usually a gas station every ~25 miles, we would tend to say that for "average drivers" such a small difference in MPG is not considered significant.
(* - such as through low rolling resistance tires)
BTW, a car's MPG is an interesting analogy because like diving, there are sources of performance variation that aren't strictly the hardware alone. Factors such as the product's "Driver" (habits like jackrabbit starts, junk in trunk) as well as their operating environment (City driving vs. Highway; plains vs. mountains, speeding, etc) can each have a measurable impact on MPG, and these may be greater in magnitude than discrete hardware changes, which would tend to deemphasize the significance of the hardware if through no other means than adding more variance.
- - -
Bringing this back to diving, let's say that improved streamlining from a BC style change works out to, say, a 50psi savings on an AL80 on a single tank dive. This hypothetical 50psi savings on an AL80 is ~2%, which is mathmatically equivalent to one extra minute per hour of bottom time. Or you could reduce your air consumption by this same 2% by choosing to dive at a depth of 58fsw instead of 60fsw.
Based on this hypothetical example value, the follow-on question is then: is that significant enough to be worth pursuing?
For some divers, this difference is going to be significant for their needs. For others, it is not. The answer depends on their diving needs, as well what the "costs" are to capture that gain, what other alternatives and trade-offs can be considered, and also if it is really a "need" (versus a desirous "want").
Sure, we all want more available Bottom Time, but every time we come up with more than 500psi (proverbially) is firsthand proof that there was some other factor that was ultimately more important.
-hh