As soon as you indicated you were already at some depth on a dive, and needed to be begin descending and turning, and that this required a 2nd dump valve to be optimal, it pretty well laid the foundation for this interpretation
Upward currents by a wall are rarely experienced by most divers....same with down currents. For the discussion, we will assume you were in a place where there is such a thing--and if so, fin power is much easier to regulate speed up or down with....but----if fin power is not enough, then the BC may be required in such an unlikely emergency scenario. Also, this would be a good reason to use freediving fins, in a place where up or down currents, are a "norm" to be dealt with.....and doing bicycle training like a racer of 100 to 200 miles per week, including interval days, to ensure that you have the fitness to
easily swim against such currents. ( usually when I start my "you need freediving fins" rants, the first thing I hear are whines about how divers should not need to have a high speed pair of fins......If you found a great dive site that had the added challenges of up and down currents on a regular basis, suddenly freediving fins would be
HOT! )
So that this is not all useless speculation, WHERE was this "up current"? And how likely is it that you will ever experience another?
The part about descending and turning was to give an example of how air can get trapped in the right side of your wing, not about needing to use your wing to do that. I completely agree that your BC should not be used to ascend or descend in a normal situation like that.
And then after trapping air there, in the event of a need to vent while facing downwards (because of an upward current), how a right side vent is useful.
And I have been in upward currents in the Maldives and the Philippines, usually when there is a current blowing towards a wall, then going up over the wall and going horizontal across a pinnacle. At the other side of the pinnacle, there is often a down current. I don't believe it to be a rare situation at all, although the intensity of the current is not always super strong. This seems to be quite common with a slightly angled wall (not fully vertical, maybe 60-70 degrees vertical), and when I am nearer the top of the wall.
Basically, on a wall, having no right dump turns me into a little bit of a mono-turner (a la Zoolander). From vertical I have to remember not to rotate left. Which sucks when we are moving leftwards along the wall. Maybe a poodle jacket really is the thing for me, although I do love the even weighting of a backplate, the non-squeezing nature of a wing and the simplicity of a hog harness.
So, assuming I do run into upward currents, and that I like diving walls, are we agreeing that a right side dump is useful? That a diver who happens to do such types of dives would be served better by a wing with different design?
Tobin makes a reasonably good point about donating air with my right hand, which I had not thought about. Although I do tend to have a torch in my right hand anyway, and generally assume if my buddy if going out of air (I ALWAYS check my buddy's air multiple times a dive), he/she is going to just rip mine off, and I'm obviously going to then automatically drop the dump valve and use my hand to pop my octo into my mouth.
Also, I don't disagree with the need for good fins, but you are bringing your own pet topic/agenda of freediving fins into the question. I use Avanti Quattro's, which are rated pretty decently here, and I have not felt like I was lacking power (except when chasing the shadow of a whale shark, but everyone else was slower than me anyway, so there was no point going faster and breaking off from the group). Plus, I fly to where I dive, and freediving fins aren't exactly travel friendly. And, whadaya know, I do bike and do intervals - big fan of Sufferfest videos here!
