There is no law that one cannot use masculine or gender neutral pronouns to refer to ships and other things that are normally referred to by feminine pronouns.
For instance, if a female owner wanted to name her yacht a man's name, paint that name on her yacht and refer to this yacht as he, there is no language police that can stop her.
Besides that, Is your vehicle a 'he' or a 'she'? quotes a survey that says
Nearly half of drivers think their vehicle has a gender, with 60 percent of vehicles viewed as female and 40 percent viewed as male. Of those with a gender, vehicles in Southern states are more likely to be female, while autos in the Midwest are more likely to be male [my emphasis].
There is also a current commercial on TV for an insurance company, and it starts off with a woman who has named her car 'Brad' (a male's name)...
At any rate, this question is not, to me, about what the convention is, but whether or not it is possible in English. And of course it's possible. And I see no reason to discourage a woman, or man, from doing so.
Hurricanes used to always be given female names. Now during each hurricane season, the names alter between male and female. So it's not like there is absolutely no room to maneuver regarding this subject: for whatever the reason may be, it's possible to incorporate change.
"It" is an "empty" or "dummy" subject in this case. The pronoun has no referent; it merely satisfies the grammatical function of supplying a subject for the clause. So the meaning is
Harry was happiest when the Dursleys were asleep because they were never any help when awake.
Best Answer
The antecedent to a who relative clause is always what precedes it.
There cannot be a space between the who clause and the antecedent to which is refers.
The man saw /the woman who is bringing the telescope/
VERSUS
The man /who is bringing the telescope/ saw the woman.
Two different meanings.