Though I've lived near serious water most of my life, I'm a confirmed landlubber. Happy as I am about this preference for terra firma, landlubber's not a title you'd really want to adopt. I'd always thought in a sloppy way that the word was a turn on "land lover" — and what could be wrong with that? Fact is, the seaman's insult strikes further below the Plimsoll line than I'd realized, because, according to the OED, a "lubber" is "A big, clumsy, stupid fellow; esp. one who lives in idleness; a lout." (The fact that it's a term that was occasionally applied to monks doesn't salve the self-inflicted wound.)
I thought of this just the other day as I was sifting through some photos, one of which was a recent shot of the woods into which more than a few years ago I took my very first Halloween walk, knotted into a black and orange crepe paper confection. The point is that this was on the Northwest Arm in Halifax. And down at the water there was a projection we called the jetty, a wooden structure off which my dad would cannonball — and off which we plucked mussels galore, as I recall.
Having been corrected about "landlubber" I thought I'd check on "jetty". A bit of research (i.e. messing about in sites) turned up a plethora of words to describe land or landish material thrust out into the water: jetty, wharf, pier, dock, quay, mole, breakwater, ness, naze. . . . Strictly speaking, what we called a jetty probably wasn't: the best sense of the term is of something thrust (jetée) into water to protect a harbour or a riverbank. The thing your dad jumps off might be better called a pier, though certainly of the kind less grand than the ones the Victorians enjoyed — or, as we lake-folk would call it here in Ontario at least, a "dock." Which is odd, because, properly, a dock is an absence, a hole or opening within which a boat or a ship can rest.
It probably wouldn't be a "mole." Moles require massiveness, says the OED, and commonly stone. Though if you've got those two, you might have something that would serve "as a pier, breakwater, or causeway." That last option gives us once again the reflex of a structure: the OED: "Also: the area of water bounded by or contained within such a structure, esp. forming a harbour or port."
Which seems to me, lubber though I may be, to mean that sailors have a hard time knowing whether they're coming or going. And I haven't even broached "quay" (which, weirdly, Google seems to think belongs to a specific place in Australia) or its synonym "wharf" (a collection of which is, delightfully, known as a "wharfing").
Of course, all these problems of nomenclature disappear once you leave sight of land and all its promontories — which, now that I think of it, may explain why people become sailors. I can't think of any other reason.