tending to float on a liquid or rise in air or gas
The coracle—as I had ample reason to know before I was done with her—was a very safe boat for a person of my height and weight, both buoyant and clever in a sea-way; but she was the most cross-grained, lopsided craft to manage.
Another definition of "buoyant" is "characterized by liveliness and lightheartedness"—this also seems to fit Jim's description of the little boat, because he personifies it by calling it "she" and seemingly comparing it to a willful woman who would never go in the direction she's pointed towards because she prefers to turn around and around in circles.
"But one man of the crew alive,
What put to sea with seventy-five."
And I thought it was a ditty rather too dolefully appropriate for a company that had met such cruel losses in the morning.
uninterrupted in time and indefinitely long continuing
The ship was talking, as sailors say, loudly, treading the innumerable ripples with an incessant weltering splash; and until I got my eye above the window sill I could not comprehend why the watchmen had taken no alarm.
Among the fallen rocks the breakers spouted and bellowed; loud reverberations, heavy sprays flying and falling, succeeded one another from second to second; and I saw myself, if I ventured nearer, dashed to death upon the rough shore or spending my strength in vain to scale the beetling crags.
showing the wearing effects of overwork or care or suffering
It was a smile that had in it something both of pain and weakness—a haggard, old man's smile; but there was, besides that, a grain of derision, a shadow of treachery, in his expression as he craftily watched, and watched, and watched me at my work.
Now the coxswain's hesitation seemed to be unnatural; and as for the notion of his preferring wine to brandy, I entirely disbelieved it. The whole story was a pretext.
Well, while things stood thus, suddenly the Hispaniola struck, staggered, ground for an instant in the sand, and then, swift as a blow, canted over to the port side, till the deck stood at an angle of forty-five degrees, and about a puncheon of water splashed into the scupper holes, and lay in a pool between the deck and bulwark.
In the horrid pain and surprise of the moment—I scarce can say it was by my own volition, and I am sure it was without a conscious aim—both my pistols went off, and both escaped out of my hands.