Is this BCD's buoyancy enough for me?

[Vitesse2l]

I dive a broadly similar setup to you OP.

Just checked my bcd - it has 170n lift.

 

[Silt Life]

The Ups and Downs of Buoyancy Control — DAN | Divers Alert Network — Medical Dive Article
Excellent read.......

 

[David Novo]

That's 12kg of lift. (newtons units of force ... F=mg where g is the acceleration on earths surface due to gravity.... 9.8m/s/s and m is the mass in kgs)
If you have 8kg of lead, that gives you 4 left.
Your regulator is at least 1kg and add another 1kg for other gear.
That's 2kg left for your tank.
You didn't say what kind of tank you use, but if you use an AL80 that will add 1kg when full.
That gives you 1kg of lift to spare.

Correct me if I am wrong, but, in theory and assuming the OP is correctly weighted, I think it just needs to be enough to compensate for the weight of the gas in the tank + loss of buoyancy of the suit due to compression.

Regarding your question, I have a similar height/weight but I wear 6 kg of lead on the belt, without backplate. Do a proper weight check (end of the dive, with tanks nearly empty, when you are lighter).

From the excel on the post below, you can see that your suit should not lose 12kg (minus of the buoyancy of your full lungs) of lift between the surface and 30m, so if you can float in the beginning of the dive (when you are heavier), you will probably be ok.

Optimal Buoyancy Computer

 

[Angelo Farina]

I think that, if the amount of weights is calibrated correctly, this BCD is OK with a 7mm wet suit and a single cylinder of 15 liters, if the max depth is around 30 meters.
In fact the label states that the maximum tank should be a 18-liters single or a 20-liters double.
Regarding the size, for me a small one is better than too large: a large BCD will move all around. A small one will fit perfectly, just leave the straps a bit longer.