Question: Do you use a magnetic compass to augment your navigation process?
Answer: Yes, we do. We have a large Ritchie compass mounted on top of our binnacle. Despite having two flux gate compasses (it’s a long story why two) we like to check the course with the magnetic compass, which we treat as the master compass. It’s also much easier to take a bearing sighting over it, particularly in rough weather, than using a hand bearing compass, since it has much better damping.
We have the Ritchie professionally adjusted for deviation any time we make any changes to the location of metals around it, or about every 3 or 4 years. I also check it occasionally via sun azimuth.
We would not consider relying totally on flux gates since their deviation drifts quite a bit as our latitude changes, particularly in the high latitudes.
An accurate compass is still important to us since we do not just blindly follow a GPS waypoint without checking that the course makes sense. By doing this, any error in entering a waypoint becomes apparent before it can do any harm.
Finally, the magnetic compass, together with an old Walker log and sextant, is an important part of our equipment to allow us to navigate in the event of a total power failure. Unlikely I know, but Murphy is always lurking at sea.