measure magnetic field

[Jens Noriʇzsɔɥ]

I would not necessarily trust the Samsung in this regard as the magnetic fields inside a smartphone are far greater than the tiny earth's magnetic field. The sensor is continuously recalibrated and I suppose that small differences are quite relevant for a ship's heading.

On first sight, https://boatingforbeginners.com/where-to...t-compass/ appears to give some reasonable recommendations on potential problems and where best to mount a compass.

Hope that helps a bit