I didn't try them on at the shop but at my poolclessons I use a mares jacket BCD medium so I thought same brand same thing? I'll get myself to a dive shop and try them on. I'm quite a long way from a dive shop do was hoping for remote. My biggest worry really was being to heavy for the BCD to keep me afloat I'm guessing that would be unlikely?
Short version, 35 LB lift should be more than enough for most single tank diving. Long version, proper amount of lift has little to do with body weight... It's all about buoyancy. Think of it this way:
1: You have individual buoyancy (do you float or sink in a pool wearing a swimsuit, and how much lead it takes to sink or how much added lift to float)
2: Exposure protection, i.e. wetsuit or drysuit (always a positive buoyancy, amount varies by type of suit)
3: Rig (tank, BCD, regset assembly)... depending on tank may be a positive or negative value.
When properly weighted (correct lead for you in your configuration) you should be neutral at 15 ft. with approximately 500 PSI/35 Bar with little or no air in the BCD.
So the BCD has 2 requirements:
1: Addressing buoyancy swing through the dive (tank starts approx 2.5-3 kg heavy due to the air you will use up, wetsuits compress at depth reducing buoyancy)
2: Supporting the rig itself at the surface if you have to take it off in the water.
Extreme examples of #1: Warm water no wetsuit, LP72 steel tank, my total buoyancy swing is 5 LB... I use a 14LB lift BCD and it's more than enough. Other extreme, a 7 mm full suit with a steel 120 the suit may have as much as 16 LB of lost buoyancy at depth due to suit compression, and the tank is going have 10 LB of air I can use... so 26 LB lift minimum would be needed.
Now looking at those examples in terms of item 2: First example, with that steel tank on my aluminum plate and my old school brass regs, the whole rig is about 10 LB negative at the start of the dive.... so even though I only need 5 LB lift to account for buoyancy swing, I need at least 10 LB to account for being able to float the rig by itself. My 14 LB lift wing still works out.
Second example, the buoyancy characteristics will be largely determined by whether you use integrated weights or a separate weight belt (or a combination). That steel 120 will be quite negative (around 10 LB negative at the start of the dive), then the BCD buoyancy (which will include any integrated weights). So if you use more than 16 LB of integrated weights, the rig becomes your limiting issue for minimum lift requirement. And unless you have over 15 LB of integrated weights, the 35 LB lift BCD is still sufficient.
Respectfully,
James
