It is important to note that although Stephen tends to bicker with Jack almost constantly, one of his primary motivations for doing so stems from a quiet fascination with the way in which the man views the world. Though there are certainly points in which they butt heads on a genuine level  –  and there are indeed topics to which they stand at polar ends  –  for the most part, Stephen holds a genuine respect for Jack’s ideology and passions.

It is in part for this reason that he constantly asks about the ships and sails and other bits and bobs – not because he can’t retain it – or even because he is all that interested in understanding the difference between a reefing line and a reefing cringle – but rather because it sets Jack off on tangental escapades that are a genuine entertainment for him. 

It is a harmless means of seeing the man’s more excitable edge without bearing the risk of argument, and in truth a part of Stephen incites these tangents to learn how to be more engaging when speaking about things a listener might not care about. He knows himself to be painfully monotonous even when he is talking about something he has spent years researching and believes that through observing Jack, he may learn to become a better public speaker. 

@seafaired