Less weight with a BP/W?

[ifukuda]

I'm in the process of putting together my first BP and Wing BC (it'll be complete in a few days, as soon as the Wing arrives via UPS):
1) BP: FredT SS 6lbs
2) Wing: Dive Rite Venture
3) Harness: Dive Rite TransPlate
4) Generic Tank Bands x2
5) XS Scuba Weight Pockets x2

I dive in So Cal in a 7mm Wetsuit with single AL63 and AL80 tanks. I currently use 18~20lbs of lead with the SQProQD+ (it's taken me quite some time to get my trim just right so I can dive with 18~20lbs of lead). I've seen several posts from various divers that claim they've dropped significant amounts of lead after switching to a BP+Wing BC.

Is this just a matter of the BP replacing 6 lbs of lead? Or, do people actually need less ballast to be neutral in a BP+Wing setup? This information would be very useful to me during the set up of my BC. Currently, the BP (-6lbs.) and the 2 XS Scuba pockets (-5lbs. max x 2) would give me a total of 16lbs of negative buoyancy. It would be ideal if I only need <= 16lbs or lead.

Otherwise, I was thinking of threading additional 2lbs block weights onto the waist strap, over the shoulder strap base plates (item [8] in the TransPlate manual).

I'd really appreciate if the experienced BP+Wing users on this board would advise how much ballast you are using, and how you are distributing it.

Thanks!

 

[The Kraken]

ifukida,
I was diving a 6.5 farmer john/jacket using 22# in fresh water with my BC. When I went to the BP/W I was able to drop 10# of weight. I'm 5'8" and weigh 165#. I don't know your physical characteristics, but you can expect a similar weight reduction.

Try 12# and see how it goes. You'll be in the ball park with this amount.

 

[Spectre]

Is this just a matter of the BP replacing 6 lbs of lead? Or, do people actually need less ballast to be neutral in a BP+Wing setup?

No. Yes.

It's basically the difference in inherit bouyancy of a BC vs. a wing. BCs have more air pockets and just floaty stuff, a wing is much less positive.

 

[The Kraken]

The 12# that I do use are placed 6# per side in ditchable weight pockets located on my waist band between my side d-rings and the back plate.

 

[FreeFloat]

I went from a jacket BC to a backplate around New Year's. I remember thinking much the same - I had been using 19# with the jacket, and knowing the backplate was "worth" at least 6 lb, I dropped my weight to 13lb on the belt.

I was unbelievably negative, that first dive. Fortunately, one of the local GUE guys, knowing I was new to the backplate, pointed this rather obvious fact out to me.

On subsequent dives I dropped 2 pounds each until I was able to maintain a horizontal hover at 15' with an empty (~500psi) tank. I don't hold much faith in those vertical weight checks as I'm seldom anywhere near vertical.

I finally ended up with 6lb on the belt when diving my steel tank, and 10lb under an aluminum tank. I know this weight is perfect for the wetsuit I dive, and in fact on my recent DIR-F these weightings were confirmed as "just right."

So you see, 19lb = 6lb + 6lb (bp). That's Halcyon math

 

[Rick Murchison]

Why all the guesswork?
Take your old kit and put it in a mesh bag and see how much weight it takes to sink it.
Take your new kit and do the same.
Subtract.
Rick

 

[Wristshot]

Rick,

As the people I work with often say; "there you go again, thinking logically!".

They mean it as an insult, but I take it the other way. Your response was the best chuckle I have had to day. Thanks for that.

Wristshot

 

[ifukuda]

Thanks for the data, it's very helpful. I'm glad that I probably won't need to thread additional block weights to the waist strap webbing.

Why all the guesswork?
Take your old kit and put it in a mesh bag and see how much weight it takes to sink it.
Take your new kit and do the same.
Subtract.

No pool access. My apartment gave me a really hard time last time I did a weight check in the pool. If pool access wasn't a problem, I'd just suit up and jump into the pool with the new BC. Unfortunately, I'm stuck doing my weight/trim adjustments in open water.

FYI: It's possible to get the same results, by just figuring out how much weight it takes to sink the ProQD+.

 

[jagfish]

I dropped 8 pounds in my switch.

However, I think it might be hard to attribute the drop in weight to the equipment change only. It may be that many divers also take their diving to a new level in making the switch, and fine tune their bouyancy/weighting in the process.

JAG

 

[Mar Scuba]

You need to look up Terry Lee May or Mike Kane. They will set you straight.

Too bad you couldn't dive with me on the Spectre last month...