Abstract: A system is demonstrated for heave neutralisation of semisubmersible platforms that can be built into any conceivable configuration of such platforms. That the system is also conceivably active and predicatively can be controlled can be concluded by analysing the appended calculation models. As an example FIG. 18, column E, is mentioned, wherein the water volume increments in the rise canister are 37 cubic metres for each half metre of wave height, so that, with reference to column A, from H=10.5 m to H=12 m is 4×37 148 cubic metres more than 150 tonnes—simultaneously with the air pressure, shown in column K, increasing from 123.86 to 131.05 kPa, a difference of just 6.19 kPa (0.0619 bar or 61.9 millibars). Large ballast volumes can be moved out and in of the system at small pressure changes and short response time.