Perhaps the thread is a little old, but I just came across a bit of information which might clarify why the ships' names are capitalized, so it is seems pertinent to pop it in here.
It seems that it is a convention recognized in maritime law.
The passage in question (which
can be read in full here) tackles how a ship's name should be recorded, and points out that as they often come from other sources (e.g. using the names of people), they can be difficult to identify in among other prose.
It is thus suggested that a ship's name should be dealt with in one of four ways: 1) Double inverted commas (or quotation marks), which are used in Law Reports; 2) By capitalization, which, it is said is common in the shipping industry; 3) Italicization, which is said to be the method in literature and the press; and finally, 4) Underlining, used in literature which doesn't use italics.
So it can be taken that perhaps back in the days when shipping had a greated prominence in every-day life, people were used to such conventions, and understood that names of ships were often capitalized; it may even have imparted a note of verisimilitude to the text, making it seem more lifelike and real (in the same way in which putting in lots of technical gabble about guns and ammunition into James Bond books makes it seem more "real").