The unevennesses of a chuck are measured at various positions and are stored, as discrepancies from an idealized plane, in a databank. The rotation mechanism includes a rotary shaft, and a support unit that supports the rotary shaft rotatably through a bearing and sealing member. The base station has a transmitter that transmits communication signals along at least two carriers per sector within a cell. The aeration pump is in fluid communication with the aeration tube and supplies pressurized air to the aeration tube during operation of the marine vessel or RV.