I don't have experience in the merchant marine. In the U.S. Navy, watches nominally start and end on the even hour - for example, the mid-watch runs from midnight to 8am. BUT, while it's not necessarily written down, the oncoming watchstanders are obliged to arrive at their station 15 minutes before the official start of the watch - for the mid-watch, that would be 11:45pm. I'm wondering if this was the practice in the Royal Navy or aboard commercial British ships?
You may wonder why this 15 minutes difference is rigourously observed. There are several reasons that are given. One is that it is a courtesy to the watch being relieved - they get relieved a bit early. But, that is somewhat silly, because everbody gets relieved early but they also have to show up early.
Another reason given is that it allows 15 minutes for the oncoming watchstanders to get the dope on the situation. Except for perhaps the officer of the deck, it doesn't take 15 minutes for the helmsman, lookouts, etc., to learn the situation: things like course, speed, who has the deck, etc. If it takes only 2-3 minutes to learn the situation, then the off-going watchstander stands relieved.
I suspect the real reason is custom and tradition, many of which were handed down from the Royal Navy to the U.S. Navy. Since many of Titanic's officers had ranks or experience in the Royal Navy, perhaps they would have set a 15-minute-early practice? You can see where I'm going with this.
You may wonder why this 15 minutes difference is rigourously observed. There are several reasons that are given. One is that it is a courtesy to the watch being relieved - they get relieved a bit early. But, that is somewhat silly, because everbody gets relieved early but they also have to show up early.
Another reason given is that it allows 15 minutes for the oncoming watchstanders to get the dope on the situation. Except for perhaps the officer of the deck, it doesn't take 15 minutes for the helmsman, lookouts, etc., to learn the situation: things like course, speed, who has the deck, etc. If it takes only 2-3 minutes to learn the situation, then the off-going watchstander stands relieved.
I suspect the real reason is custom and tradition, many of which were handed down from the Royal Navy to the U.S. Navy. Since many of Titanic's officers had ranks or experience in the Royal Navy, perhaps they would have set a 15-minute-early practice? You can see where I'm going with this.