How do you measure the magnetic field of a ship?

Measuring the magnetic field of a ship can involve various methods, but one of the most effective techniques is ranging, which involves measuring the magnetic fields at varying distances from the ship along with certain reference points. This method helps in accurately determining the extent and direction of the magnetic field generated by the ship's structure and equipment.

Ranging allows for a systematic collection of data, which can then be analyzed to understand how the magnetic field behaves around the ship. This is especially important for ensuring that the magnetic interference from the ship does not affect navigational instruments like compasses or other electromagnetic systems onboard.

While compass readings can provide some information about the magnetic field, they may be subject to interference from the ship's own magnetic fields and are not as precise for a full assessment. Calibration generally refers to adjusting instruments for accurate readings rather than measuring the magnetic field itself. Electromagnetism checks involve evaluating specific electrical components or systems, but they might not provide a complete picture of the ship's overall magnetic field effects.