BP/W Weights

[Lifter]

Hi All - I purchased a XS scuba BP/w back in November and have only used it on a trip to Maui in October. During my dives I only used 8lbs of weight and no wetsuit. Unfortunately, I have not been able to get back out on a dive since. Well, now I’d like to get back out there and get some dives in and I want to get your advise on weight. While diving with a 7mm suit, steel tank, steel BP, and weighing 240 lbs what weight should I be looking to put in my dive pockets? Would 25 lbs be to much or to little to start with? Your help is appreciated.

 

[swimlikethefish]

Assuming you have the appropriate amount of lift...

Get fully dressed, tank and all. Get in the water. Start adding weight until you have enough to just start to sink. Then add 7 more pounds (this compensates for the air lost in the tank during the dive).

Or do a site search, there is a weight and bouyancy calculator here somewhere.

 

[David Novo]

Assuming you have the appropriate amount of lift...

Get fully dressed, tank and all. Get in the water. Start adding weight until you have enough to just start to sink. Then add 7 more pounds (this compensates for the air lost in the tank during the dive).

Or do a site search, there is a weight and bouyancy calculator here somewhere.

Optimal Buoyancy Computer

Were you diving an aluminium or steel tank in Hawai? What are the sizes of both tanks? Did you have that bp in Hawai? Are you wearing boots, hood and gloves now? How thick? These are just some of the variables that will will affect the answer.

 

[Lifter]

Assuming you have the appropriate amount of lift...

Get fully dressed, tank and all. Get in the water. Start adding weight until you have enough to just start to sink. Then add 7 more pounds (this compensates for the air lost in the tank during the dive).

Or do a site search, there is a weight and bouyancy calculator here somewhere.

thank you.

 

[Lifter]

Optimal Buoyancy Computer

Were you diving an aluminium or steel tank in Hawai? What are the sizes of both tanks? Did you have that bp in Hawai? Are you wearing boots, hood and gloves now? How thick? These are just some of the variables that will will affect the answer.

I was using the BP/W in Hawaii. The tank was aluminum but I can’t remember the size. As for diving here in SoCal I will be in full dress: wet suit, boots, hood, gloves. In my previous dives in full dress and a vest style bcd it took 30lbs to get me down. However, I know there is less boyance when it comes to the harness system. I’m thinking I may need to go on a boat dive and start with adding weight until I sink as suggested above.

 

[David Novo]

I was using the BP/W in Hawaii. The tank was aluminum but I can’t remember the size. As for diving here in SoCal I will be in full dress: wet suit, boots, hood, gloves. In my previous dives in full dress and a vest style bcd it took 30lbs to get me down. However, I know there is less boyance when it comes to the harness system. I’m thinking I may need to go on a boat dive and start with adding weight until I sink as suggested above.

Bear in mind that "30lbs to get you down" in the beginning of the dive is different from "30 lbs to keep you down" while ascending in the end of the dive. You will lose the weight of the gas in your tank.

If your goal is to be neutral in the end of the dive at the surface (negative at your shallowest safety/deco stop), just make a weight check in the beginning of the dive and add the weight of your gas in lead. It is not optimal, but for sure you will not be positive in the end. Ideally you should do the weight check in the end.

Other issues you should consider are:
1) What is the lift of your wing?
2) How deep are you diving?
3) Can you swim up all that lead if your wing fails in the beginning of the dive?

 

[Esprise Me]

For ballparking weight, I still really like this simple tool:
DiveBuddy
A couple of caveats: you should choose your experience level as "expert" even if it's not; anything else will just add unnecessary lead. And you'll need to do the math yourself on subtracting the negative buoyancy of a backplate from the total you're given (6 for steel, 2 for aluminum). But plugging in your given weight of 240, with only a swimsuit/dive skin, and assuming an AL-80 tank, I get 14 lbs., which is exactly what you used--8 lbs. of lead, plus a steel backplate with 6 lbs. negative buoyancy. So changing it to a one-piece 7mm with hood, boots, and gloves, and with a steel hp-100, it suggests 23 lbs. So I would start there and do a weight check, especially if you don't have enough information on your personal buoyancy to use the board's Optimal Buoyancy Computer.

 

[tbone1004]

@Lifter

if that was a SS plate then you shouldn't have needed more than 2-4lbs. Either way, using the general 2lbs/mm rule, you'll need another 14lbs to deal with the 7mm suit. I don't recommend pockets with bpw's and much prefer weight belts

 

[Lifter]

@Lifter

if that was a SS plate then you shouldn't have needed more than 2-4lbs. Either way, using the general 2lbs/mm rule, you'll need another 14lbs to deal with the 7mm suit. I don't recommend pockets with bpw's and much prefer weight belts

Thank you. Yeah I’m pretty sure I was overweighted while diving in HI with my SST plate. I’ve already purchased the pockets but I may go a head and pick up a belt as well.