Hi there!
The best source for this is "Ships rules" published by the International Mercantile Marine Company (who owned White Star Line, and therefore paid for and owned Titanic), July, 1907. Luckily we still have it! It outlines every duty of every officer, so I'll quote extensively from it here and then elaborate on how this worked on Titanic.
- Sea Watches. – Regular sea watches must be kept from the time the ship leaves the port of departure until she reaches the port of arrival. The watches are to be equally divided and the ship is never to be left without and Officer in charge of the bridge. When the Officer of the watch believes the ship to be running into danger it is his duty to act at once on his own responsibility, at the same time he is immediately to pass word for the Commander. The Chief, First and Second Officers are never to give up charge of the bridge during their respective watches unless with the express permission of the Commander. When the Watch is relieved the Officer in charge of the watch going off duty is to be responsible that the correct course is passed with the helmsman relieving. This should be done in the presence of the Officer relieving, who is to satisfy hemself that it is being steered. The thre Seniors are the Bridge Officers, and divide the time into three watches of four hours’ duration, each will have four hours on the ridge in charge of the ship, followed by eight hours below. The Junior Officers, when five or more Officers are borne, will keep watch and watch with the seamen, the Third Officer having charge of the starboard watch, and the Fourth Officer the starboard watch, under the direction of the Senior Officer on watch. They are also to go the rounds every hour during watch on deck, reporting having carried this out to the Senior Officer on watch.
Senior Officers’s Watches: –
Chief Officer ... 2 a.m. to 6 a.m. and 2 p.m. to 6 p.m.
Second Officer... 6 a.m. to 10 a.m. and 6 p.m. to 10 p.m.
First Officer ... 10 a.m. to 2 p.m. and 10 p.m. to 2 a.m.
The First Officer relieving for Breakfast.
The Second Officer relieving for Lunch
No dinner relief needed.
Junior Officers’ Watches: –
Midnight to 4 a.m.
4 a.m. to 8 a.m.
8 a.m. to Noon
Noon to 4 p.m.
4 p.m. to 6 p.m.
6 p.m. to 8 p.m.
8 p.m. to Midnight.
Junior officers are not to have charge of a watch at sea except during dayling in fine weather at the discretion of the Commander.
On Titanic-
Henry Wilde: 2:00pm - 6:00pm.
Charles Lightoller: 6:00pm - 10:00pm.
Will Murdoch: 10:00pm - 2:00am.
Henry Wilde: 2:00am - 6:00am.
Charles Lightoller: 6:00am - 10:00am.
Will Murdoch: 10:00am - 2:00pm.
These three men were responsible for navigation and were never allowed to leave the bridge during their watch (they weren't even allowed to sit).
- Station. – At sea the station of the Officer of the Watch is on the Bridge, which he must on no account leave, either night or day, without being relieved.
When the watch is changed, the Officer who is being relieved will remain on the ridge and in charge during the change; he will see that the seamen placed as look-outs do not quit their posts until relieved, and he must deliver to the Officer relieving him all orders wich have still to be executed. He is the resonsible Officer until he leaves the Bridge, and must not leave the bridge until the Officer relieving him has had time to familiarize himself with his surroundings.
- Duties. – (a) He must remember that his first duty is to keep a good look-out, and avoid running into danger, and though it is desirable to obtain the position of the shaip as often as possible, he must on no account neglect his look-out to do so. He must also preserve order in the ship.
(b) He must not alter the course without consulting the Commander, unless to avoid some sudden danger, risk of collision, etc.
(c) When he believes the ship to be running into danger it is his duty to act at once upon his own responsibility, at the same time he will immediately pass the word to call the Commander.
(d) When it is his duty to alter the course for some approaching or crossing vessel, he must do so in plenty of time, signify by sound signals such alteration, and give such vessel a wide berth.
(e) He must call the Commander at once if it becomes foggy, hazy, if he does not think he can see a safe distance, or if in doubt about anything.
(f) He is expected to make himself thoroughly conversant with the usual Channel courses, and to be thoroughly posted in the run of the ship. Any doubt he may have as to the safety of the position of the ship or of the course steered he will immediately express to the Commander in a respectful manner.
- Steering and Compasses. – He must pay particular attention to the steering and the course the ship makes. He must steady the ship on her course by standard every half-hour, and must compare the compasses every Watch, the comparisons to be entered in the Compass Comparison Book for reference. He will also ascertain the deviation as often as possible.
In regards to point 253- while this was the Officer of the Watch's duty, on Titanic it was given to the junior officer on deck and overseen/double checked by the senior officer on deck
After each watch, the senior officers would hand over command of the ship to their relief and do their rounds- which included a general checkup and review that everything was functioning, and required them to walk all over the labyrinth that was Titanic. From "Ship's rules"-
Evening Inspection. – at 8-0 p.m.the Chief Officer or Senior Officer of the Watch when relieved, will make an ispection of the ship, satisfy himself that the Fire Gear is ready for use, Sluice Valves shut, Fire Detectors in order, Emergency Boasts clear and ready for lowering, that the proper arrangements are made for closing any Side Ports that may be open on the cattle decks when necessary, and will report the same to the Commander as soon as possible afterwards.
The Junior Officers- Herbert Pitman, Joseph Boxhall, Harold Lowe, and James Moody- had slightly different responsibilities. One of each would be stationed on the starboard and port wings of Titanic, and would rotate out (Boxhall would relieve Moody, Pitman would relieve Lowe and vice-versa).
Junior Officers were also required to calculate the ships position by the stars (Lightoller testified that James Moody had miscalculated when they would be approaching ice on the night of the 14th), as well as stand in the wheelhouse to make sure the Quartermaster was staying on course and correcting compass errors. Other duties included-
JUNIOR OFFICERS
- Duties. – (a) The Junior Officers should exert themselves to afford every assistance in the navigation of the ship by perfecting themselves in the practice of solar and stellar observations, bot for the correction of the compass and for ascertaining the position of the ship.
(b) They will attend strictly to the instructions of the Officer in Charge as to superintending holds, gangways, or in keeping watches, and perform any other duties which may be required of them.
(c) Junior or Petty Officers must supervise the holds during loading or discharging to control the stowage, and prevent stealing and the improper use of hooks and crowbars by the stevedores.
Part 2 continues below!