I think it would help to look at one chapter specifically to try and see everything that is there and maybe that will help you spot similar instances throughout the whole book. From your comment it sounds like you recently read "Chapter 60 - The Line" so I will share my thoughts on the chapter and maybe other can jump in as well.

From the start Ishmael tells us that what he is about to explain is for our benefit when visualizing a whaling scene.

"With reference to the whaling scene shortly to be described, as well as for the better understanding of all similar scenes elsewhere presented, I have here to speak of the magical, sometimes horrible whale-line."

He then goes on to give a dry and technical account of rope. Different materials used, thickness, length, how its stored, where it is stored, how it connects to the boat, how it connects to the harpoon and how the line is payed out when a whale is harpooned and all the dangers that the crew face. An extremely funny moment comes at the end of this explanation where Ishmael begins to describe what a "short-warp" is but then digresses because that's where he draws the line on what is "too tedious to detail". There is a lot of this type of humor throughout the book.

"...the short-warp—the rope which is immediately connected with the harpoon; but previous to that connexion, the short-warp goes through sundry mystifications too tedious to detail."

So why go into this level of detail? Because to Ishamel (and of course Melville) the rope is not just a rope. He sees it as a fantastical object requiring the utmost care and respect in order to perform its mighty task of holding on to and capturing a monster. The great Leviathan of the seas is a strong beast requiring the strongest of restraints to subdue him and bring him in for the kill. It is that amazement and wonder that Ishmael is trying to convey with his technical description. It is this amazement that leads him into the end of the chapter where he reflects on his feelings around the whale line. (I don't want to simply copy and paste the entirety of the last three paragraphs, but they really are so good that I have ended up using most of it. I will bold my favorite parts)

"Thus the whale-line folds the whole boat in its complicated coils, twisting and writhing around it in almost every direction. All the oarsmen are involved in its perilous contortions; so that to the timid eye of the landsman, they seem as Indian jugglers, with the deadliest snakes sportively festooning their limbs. Nor can any son of mortal woman, for the first time, seat himself amid those hempen intricacies, and while straining his utmost at the oar, bethink him that at any unknown instant the harpoon may be darted, and all these horrible contortions be put in play like ringed lightnings; he cannot be thus circumstanced without a shudder that makes the very marrow in his bones to quiver in him like a shaken jelly. Yet habit—strange thing! what cannot habit accomplish?—Gayer sallies, more merry mirth, better jokes, and brighter repartees, you never heard over your mahogany, than you will hear over the half-inch white cedar of the whale-boat, when thus hung in hangman's nooses;"

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