A Fenzy? I retired mine over 20 years ago. It has around 50 lbs, so 24 kg would be a bit closer, but with the bottle, that is around 18 kg.Thalassamania:We used to be hard core and insist on hoods and all ... but after a few folks almost passed out from head exhaustion we backed off.
It's perhaps the most difficult skill, but it's all in teaching a surface dive that gets the fins in the water, after that a dolphin kick down and the suit compression at 13 feet makes it easy enough. As a first step we teach a jacknife to a vertical hold (head down), once they get that the rest is easy. We got interested in just how much buoyancy one could "drag down." Most of the staff instructors could make it too the bottom with a fully inflated Fenzy, which I think is a bit more than 25 kilos buoyant.
That's exaclty the suit we use.
With all due respect, you do not have to perform at the level that these folks do, the system works and on sheer physicality I'd stack our weakest wegghead up against the wrastiest wrecker any day (and when it comes to level of knowledge ...), and our strongest ... well that's a whole 'nother story, he was a Division One Football player and an Olympic Trials level swimmer, he'd wax your tail and then some, wax on ... wax off Grasshopper!
We tried that in the ocean about 3 weeks ago. My wife can do a perfect pike, and her feet never touch the water, not even close. She does not have enough body mass to overcome the buoyancy Me, I weigh enough to get there. Fresh, pool water can be your friend at times.