Please evaluate my weight calculation, Buoyancy

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

rnln

Contributor
Messages
211
Reaction score
37
Location
SoCal
Previously, I went with back inflate BCD, and the jacket BCD before. Now, I am ready with my BP/W. This will be the first dive with BP/W for me. Can experienced help evaluate my plan on weight below?

I am 5'9", 200lbs on average day.

I used back inflate BCD, 7mm farmer John wetsuit, AL80 tank, 30lbs weight. I could get down ok.

With jacket BCD, 7mm farmer John wetsuit, AL80 tank, 32lbs weight. I really had hard time to get down. The dive master had to help pulling me down a bit to initiate the descenting. Still, I had hard time staying down there.

Now, I have BP/W. Base on the back inflate with 30lbs of weights:
OMS stainless steal back plate, DSS single wing: - 7lbs
5mm wetsuit, non-farmer John: - 4lbs

30 - 7 - 4 = 19lbs. Should I try 19lbs? Or should I start with 20lbs to make sure can get down, rather a little heavier than lighter?

Thank in advance.
 
Nothing beats the weight check at your SS and the slow, controlled ascent to the surface. I dive a back inflate, with an AL80, I use 14 pounds with a full 5 mm +/- a 5/3 mm hooded vest. You did not give your size, I'm about 5'10". 185 pounds. 20 pounds sounds like it may be a place to start. Really, 7 pounds from a back inflate to a BP&W? I dive a SP Knighthawk. Better to be a little heavy than too light
 
If you can't get down with a full tank, you won't be able to hold a safety stop.

Add 5lbs at least first or to your buoyancy check with a bear empty tank.
 
Nothing beats the weight check at your SS and the slow, controlled ascent to the surface. I dive a back inflate, with an AL80, I use 14 pounds with a full 5 mm +/- a 5/3 mm hooded vest. You did not give your size, I'm about 5'10". 185 pounds. 20 pounds sounds like it may be a place to start. Really, 7 pounds from a back inflate to a BP&W? I dive a SP Knighthawk. Better to be a little heavy than too light

Sorry, I missed my size. I just added it.
I took 7lbs off for the DSS SS back plate, and 4lbs to go from 7mm farmer john to 5mm 2 pieces.
 
Sorry, I may have missed it, is your BP&W with a steel or AL backplate? That may have been my problem.
 
Sorry, I may have missed it, is your BP&W with a steel or AL backplate? That may have been my problem.

I never wear a BP/W. This will be my first time, it will be SS, DSS. I have worn jacket and back inflate BCD.
 
Its too important to "think" you have it right. Test it!
  1. Get a tank with 500 PSI and test your buoyancy. Can you hold a safety stop?
  2. Yes, great you passed your buoyancy test.
  3. No, adjust and repeat until you do.
Its too simple of a task to risk not getting it right. And the potential complications of an uncontrolled assent definitely aren't worth it.
 
https://www.shearwater.com/products/peregrine/

Back
Top Bottom