A method and apparatus for handling of sensor capsules and their inner components during deployment and retrieval of a seismic cable into the sea by a vessel where the seismic cable includes seismic node casings to contain the sensor capsules when the seismic cable is in the sea. The method includes the following steps: withdrawing a sensor capsule from a sensor capsule storage; withdrawing a battery unit from a battery unit storage; withdrawing a control unit from a docking station; combining the control unit and battery unit into a control/battery unit; inserting the control/battery unit into the sensor capsule and closing the sensor capsule; and loading the sensor capsule into a seismic node casing.