Passing Hull-down

Question

(I previously submitted this question in its full form to Literature SE but later realized it most likely was not appropriate for this question)

In Joseph Conrad's short story Youth: A Narrative, Conrad writes

“The night was fine. In the morning a homeward-bound ship passed us hull down,—the first we had seen for months; but we were nearing the land at last, Java Head being about 190 miles off, and nearly due north. "

Researching the term "hull-down" I found Wikipedia describing it as a phenomenon "in which the curvature of the earth causes an approaching vessel to be first visible "sails-up".

Thus would this mean that as the protagonist's ship approached Java Head, that the home-bound ship would have appeared momentarily or continually on the periphery of the former's "ocean event horizon"(radius of maximum distance perceivable by sailors from their ship) as it travelled toward the bottom of Africa assumedly?

(Some additional context, England is referred to here as home, and so I'm assuming that that ship would be intending to travel the shortest distance home, and thus travelling to the bottom of Africa, despite this intent not being presented in the text. )

Answer 1

You are correct in the meaning of the term "Hull down" - meaning the hull was not visible from the perspective of the observer, but the sails or superstructure would have been.

The home-bound ship would have appeared for some time, how long depends on how far away it was and its trajectory respective to the viewer. Given that the two boats appear to be traveling in opposite directions (i.e. Narrator's/Marlow's boat heading to Java from the UK and the other in the opposite direction, towards the UK), and are hence traveling more or less parallel to each-other, they would have been visible to each-other for some time. The Judea is averaging 3 mi/h according to Wikipedia, so a similar speed can probably be assumed for another ship.

In the absence of a physicist or someone better acquainted with the math than me, I would hazard a guess that the time of possible viewing would be in the matter of minutes to an hour or so based on my occasional observations of large ships from beaches near ports.