mxracer19:
"but on the surface have more of a tendancy to push you over face down"
Quite sorry to disagree...but I do.
Sorry Matt, I'm going to have to 'disagree with your disagreement' here.
The simple facts of the matter is that if you're trying to rest vertically on the surface, having your source of lift located behind your spine will always rotate you face-down if your center of mass is located in front of it, even if you're not overinflated.
In engineering terms, this is because of a Moment force (think "torque"), and the only way to reduce it is to either get rid of the BC & weights (not possible), or to decrease the distance ("Moment Arm") between the two by moving the two forces closer together.
The common techniques to minimize this Moment Arm with a Wing include:
- use the heavier SS backplate
- add a lead keel weight
- use steel tanks
- & with a STA (since this displaces your St tank rearward another inch or so)
- add a lead weight onto your BC's tank strap
- locate your weightbelt weights along the small of your back instead of in front.
What you'll notice is that all of these remedies involve moving weight backwards. This is because you can't move the BC bladder forwards without the BC...by literal definition...ceasing to be a Wing and becoming a Jacket BCD. Yup, that's the other way to skin this cat
The reason most people are pushed forward with a (!)BACKPLATE AND WING(!) is beacause they are overweighted towards the front or they have WAY TOO much air in their wing.
Not necessarily.
First, surface conditions can sometimes dictate "over" inflation as the appropriate thing to do. For example, a windy day in a chop can often cause breaking seas (especially near a depth change), so if you want to get your chin up out of the water to prevent drinking the entire ocean, since your head physically weighs roughly 8lbs, you're going to need an extra 8lbs of lift in your BC. FYI, if you try the "just roll onto your back" advice in this sea state, you're may get even more water in your face, as well as burn a lot more energy to try to remain in this position...hardly what any sensible person would consider to be a good idea from a "drownproofing" perspective.
Next, there can things other than just your BC/suit/etc that influence your overall trim, both on the dive and on the surface. For example, a Nikonos UW camera is going to be held in front of you because that's where your hands are
And with a good set of strobes, such a camera can easily be 3-4lbs negatively buoyant. Since the average human's roughly 10" thick and the camera's a couple of inches, you have -4lbs on a one foot long Moment Arm that's going to be hard to counteract. Similarly, if you're doing NJ wreck diving, bringing up a catch bag with a bunch of scallops will weigh you down as well, so your BC's going to have to be inflated more than otherwise.
You dont usually get this with a bp/w because your plate assuming it is stainless steel is actually ~6 lbs, and its right up against your main flotation...so they balance out.
Yes, you've balanced out one rig. But since your 3mm suit is a tropical suit, so from NJ, you're going to be getting on an airplane to go someplace warmer, and the airlines have cut their baggage weight limits from 70bs per bag to 55lbs/bag, so if you switch to an Aluminum backplate to pack light enough to avoid the rediculous overweight fees, you've lost that ~6lbs that balanced your rig, so this revised configuration's going to have you face-dunking.
Get a bp/w....you'll never go back.
I'm ready to go back to a jacket. I've been diving in my tropical setup with a wing for the past two seasons (with a Nikonos) and saying this on Scubaboard tends to tick people off when they realize that I'm not a newbie diver.
Thought Id miss the pockets that I originally wanted if I didnt get a regular bcd, but that was before I discovered D-rings. Theyre sweet.
Putting a couple of small items tucked into a pocket results in slightly better streamlining than hanging everything in the world off of D-rings.
Sure, they're more easily accessible on a D-ring...until you clutter things up with six hundred different items hanging off a pretty small piece of real estate. From a work taskloading perspective, having infrequently needed items stowed away so that there's only a couple of important & frequently used items on the D's is IMO a superior approach. Fortunately, you can fiture out ways to add pockets to many wing systems.
My current bp is the first bcd Ive ever bought, but ive tried jacket styles, back inflation, and the bp/w.
There's a difference between 'trying' something and really diving with it for awhile.
In my experience and opinion, you need at least a dozen real dives on any new piece of gear to get settled in on the equipment change and to then tune it up to be well dialed in exactly how it responds in order to get a good feel on its performance, from which one can then generate a reasonably informed opinion.
And this assumes that there aren't other learning curves interacting to disguise one factor for another...in general, the wrong time to try A-vs-B comparisons is when there's change present from other factors, such as still being a learning novice (of course), encountering a significantly new diving environment, and lastly, at the beginning of a new diving season when you're a bit rusty and are just shaking out the cobwebs. For example of the last one, I got wet last month after a ~6 month layoff and my surace equivalent air consumption (SAC) was a disappointing 0.6 ft^3/minute on the first dive, but was a more respectable 0.5 on the second. Had I had made a gear change between these two dives, I could have easily erroniously attributed the "17% improvement" in air consumption to the gear instead of to myself being out of practice.
-hh
