I am trying to design the housing for an electrical core so that it remains buoyant on the surface but can be neutrally buoyant at desired depths through ballast tanks. I am trying to figure out what the core and housing may typically weigh through specifications online of ones already made. However, the weight in air for core and pressure housing is 102.1kg buoyant while the weight in seawater for core and pressure housing is 150kg buoyant. I've never seen buoyant after a weight like that and I'm a little confused if it just means it weighs 150 kg. Shouldn't the weight be less in the water? The only thing I can think of is that the ballast tanks of the housing must be open and filled with water for this measurement? Can anyone help me understand this?