It seems to me everything would depend on the stranger.
And the facts of departure:
is it she or I who is sailing away alone;
or is each of us seeing someone off;
or—best of all—are we leaving together?
If the latter, we’ll have the entire voyage—
preferably five days or more—
to enjoy a full-blown affair and then part.
If not, then a half hour in a hastily booked
room overlooking the harbor
will present its own delights,
infinitely sweetened by the pressures of time.
As for the lines employed to effect
the seduction (I am purposely clinical),
no matter if she and I will be together
a week or an hour,
I would try, summoning all my wit,
not to make reference to ships
(especially the kind that pass in the night)
or to insinuate marine metaphors of any sort.
But urgency might overrule novelty,
forcing me to resort to something like:
“In your eyes I see the glittering port
that is my (your) (their) destination—
let us travel there without a ship.”
And if I find I am losing her with that one,
there is always the tried-and-true to fall back on,
good, not just for embarkations,
but any occasion:
“How fortunate we are to have
so little time for words …”

Nicholas Christopher, “Lines to Seduce a Stranger An Hour Before the Ship Sails”
Art Credit Linda Kim.