medcop:
I have a ScubaPro Glide Plus and I am okay with it. I, however, do not like the wrap around design and feel that I am "contained" too much in it.
What I want to do is get into a bp/w (wish I would have done this from the start.) The local shop I use sells DiveRite.
What should I look for / what should I most likely get in a first bp/w setup?
I am only doing single tanks now (doubles is most likely a couple years away) so I will mostly likely be using hp100's and on occasion maybe a 133....but want to be able to use an al80 if I don't take my own tanks on a trip.
Thanks
Medcop,
A backplate and wing is a modular BC. You can select the plate (heavy or lightweight) and wing (singles or doubles, lots of lift, or very little or inbetween) based on the conditions you dive in.
The single most important factor is the buoyancy of your exposure suit. Tank size and type play a part, but you really need to know how buoyant your suit is.
Any BC need to meet two criteria; enough lift to float your rig at the surface without you in it, and be able to compensate for the change in buoyancy of your exposure suit.
Here's a couple of examples, remember these may not apply to your condititons.
I'll assume your are using a 5 mm wetsuit with a HP 100. Further I'll assume your wetsuit alone is 16 lbs positive. By that I mean if you took just your wetsuit and rolled it up and threw it in the water you would need to add 16 lbs of lead to just sink it.
Your tank is about -2 empty and about -10 full. Your reg is about -2. A medium Stainless plate and harness is about -6 lbs.
You need at least 16 lbs of ballast to overcome the buoyancy of your suit. The plate and harness provide ~6, reg ~2, and empty tank ~2. Your rig provides a total of about 10 lbs of ballast. That leaves about 6 in a weight belt. If you need a weight belt there is no reason to use a lightweight back plate, as that just adds more ballast to your belt.
Your rig will be 10 lbs + 8 lbs (weight of the gas in a full 100 cuft cylinder) or about -18 with a full bottle. That means you need a wing with greater than 18 lbs of lift to float your rig. A 20 would be just enough and a 26 would be a good choice.
Either the 20 or 26 is enough to allow you to compensate for a fully compressed wetsuit. Your wetsuit cannot loose more buoyancy than it starts with.
Now lets assume 3mm suit, and an al80 tank. I'll assume the 3mm suit is +6 lbs.
Your rig will be at most -10 lbs with a full tank, 6 lbs for the plate and harness, 2 for the reg, and 2 for a full al 80. Your rig can provide about 4 lbs of ballast with an empty al 80. That leaves about 2 lbs in belt etc.
In this warm water scenario you could use a tiny wing like a 17 lbs lift, but that would not be enough for your heavier suit / steel tanks. Note that in both applications the weight of the SS back plate is a benefit.
Whatever you decide I would not recommend trying to buy one wing for singles and doubles. The shape and lift capacity is different for these two applications. If you try to use a doubles sing on a single tank you will negate many of the advantages of a BP&W.
Keep in mind that the more from singles to doubles is very expensive, couple sets of doubles, drysuit, lots of regulators, tarining, can light etc. Trying to save ~$300 now might seem attractive, but it's a drop in the bucket when you really decide to transition.
If you can provide the buoyancy numbers for your heaviest suit I can make a recommendation. If you don't know how buoyant your suit is I can estimate it pretty closely if you can tell me with a Specific tank, how much lead you use.
Tobin
