What do they do? Quartermaster QM
Quartermasters assist the navigator and officer of the deck (OOD), steer the ship, take radar bearings and ranges, make depth soundings and celestial observations, plot courses and command small craft. Usually they can be found next to or very near the bridge. Their operating space can be called Navigation or Chart Room. Generally the QM can be seen steering the ship (helmsman) underway.
Electronics have made the Quartermasters job much easier. The ships position, course, speed and heading are accurately reported using modern Global Positioning Satellites. The use of a sextant is a dying art.
Ocean and harbor navigation charts are much more accurate than ever before and are constantly updated and improved. Modern electronic depth finders aid in critical navigation.
Surface search radar keeps the helmsman notified of any vessels, land masses or objects around the ship at far greater distances and in poor conditions than the lookouts can do.
All this modern equipment is a definite asset to the Quartermaster however it requires much more schooling and practice than their predecessors had to endure.
Quartermaster QM now exists as Electronics Technician (Navigation) ETV on submarines.
I understand the earlier Quartermaster patch used crossed spyglasses instead of the modern Ships Wheel.