“Relieved” is military parlance for being replaced at your post. So in this case, it’s a verb not an adjective.
We rely a bit too much on electronics for safe navigation these days, IMO. Fathometers, GPS and like equipment don’t do much good if:
- Operators are not adequately trained in their operation
- The equipment is not adequately maintained
- Fixes were not being taken often enough
- Fixes were being taken, but whatever they were using for inertial navigation was not being updated with the new fixes
- The submerged obstruction was not properly charted
- Charts in use were not the correct ones
- Charts were not updated with the relevant Notice to Mariners
There are others, but these things almost always boil down to human error, particularly when steaming in otherwise familiar waters.
I’ve found from personal experience grounding my boat that a fish finder is of limited usefulness when the depth changes dramatically, particularly at high speeds when there is precious little time to stop, slow or maneuver out of the way.
He is. At the very least his career is over and at the very best he will be allowed to retire quietly.