The German captain of the Patna opted to abandon ship at the first sign of trouble. That's really all you need to know about him, and it is not good. It would be like the Skipper on Gilligan's Island abandoning the S.S. Minnow during the three-hour tour of doom. Come on, Cap'n. That's just bad form.
As it turns out, the Captain's cowardice is more than just a temporary lapse in judgment. No sooner has the crew of the Patna arrived back on shore than the Captain skips town. Before the trial has even begun. Unlike Jim, this is not a man who can face his bad deeds.
The image of the German Captain high-tailing it out of town makes for a pretty pathetic picture:
The little machine shook and rocked tumultuously, and the crimson nape of that lowered neck, the size of those straining thighs, the immense heaving of that dingy, striped green-and-orange back, the whole burrowing effort of that gaudy and sordid mess, troubled one's sense of probability with a droll and fearsome effect, like one of those grotesque and distinct visions that scare and fascinate one in a fever. He disappeared. (5.12)
Fleeing in a rickety rickshaw, the Captain is all effort, no dignity. Then again, when you've ditched a bunch of innocent pilgrims at sea, dignity is probably the least of your worries. No wonder he makes such a disgusting figure. Jim, too, is horrified by the Captain's behavior:
[B]ut the odious and fleshy figure, as though seen for the fist time in a revealing moment, fixed itself in his memory for ever as the incarnation of everything vile and base that lurks in the world we love [...] (3.5)
He's odious, fleshy, vile, base, and generally grotesque. Honestly, we're glad he bows out of the story so early. Good riddance, Cap'n.
The Patna's chief engineer is a good friend of the Patna's captain. Given that the Captain is described by Jim and Marlow as a gross, incompentent jerk, this doesn't bode well for the Chief Engineer's character. Like the other Patna crew members, the Chief Engineer quickly abandons ship at the first sign of trouble. Plus, he jumps on the anti-Jim bandwagon when the crew is drifting around in the lifeboat. This is not a man of integrity.
After the Patna incident, the Chief Engineer decides to drown his sorrows on a drinking binge and winds up in the hospital. Marlow pays him a visit, and all the Chief Engineer can do is rave about the "reptiles" on the Patna:
The clawing hand hauled at my shoulder; he leered at me knowingly. "The ship was full of them, you know, and we had to clear out on the strict Q.T." he whispered with extreme rapidity. "All pink. All pink – as big as mastiffs, with an eye on the top of the head and claws all round their ugly mouths. Ough! Ough!" (5.16)
You'd be forgiven for having no clue what this guy is talking about. At this point, it's obvious that the Chief Engineer has gone around the bend. Maybe it's the trauma of it all, or maybe it's the liquor. Whatever the case, it doesn't excuse talking about the ship's passengers in such a demeaning way. He clearly thinks the lives of the crew are more important than the lives of the pilgrims. What a prince.
You'd be hard-pressed to find a character who has a worse experience than the Patna's ill-fated second engineer. This dude ends up breaking his arm during the Patna's near sinking. Then he has to jump ship, survive in a lifeboat, and survive transport to a port before he can go to a hospital for said arm. Ouch.
It's no surprise, then, that most of the descriptions we get of the scrappy second engineer focus on the fact that he's in pain. He holds up surprisingly well, though; we'd have screamed our heads off:
The little engineer whimpered like a child, but, broken arm and all, he turned out the least craven of the lot as it seems, and, actually, mustered enough pluck to run an errand to the engine-room. (9.8)
This guy has one thing going for him: he's not as bad as the rest. Or at least he's "the least craven" of them. That's saying something.
The wandering Patna crew eventually get back to shore and go their separate ways. Like the chief engineer, the second engineer is unable to stand trial (both are in the hospital), which leaves Jim to face the music by himself.
However, Jim runs into the second engineer once again, when he's working as a water-clerk and the second engineer has gotten a job at a rice mill. The second engineer tries to buddy up with Jim, which freaks Jim out.
"Well, Mr. James" [...] "here we are together once more. This is better than the old ship – ain't it?" [...] "Wasn't it appalling, eh? I looked at him, and he put on a knowing air." (18.3)
Jim's sole wish is to forget about the Patna (or at least not have others around him find out about it), so he quickly skips town and rushes off to find a new job. Their meeting is a coincidence, of course, but it serves as a painful reminder that Jim might not ever escape his past.
The third engineer of the Patna enjoys two distinctions from the rest of the despicable Patna crew: he is the only one to get a name (George), and he's the only one who dies (of a heart attack). Well, George, you can't have everything.
Jim is traumatized by George's death, but the other crew members don't even notice at first:
Eight hundred living people, and they were yelling after the one dead man to come down and be saved. "Jump, George! Jump!" (9.24)
The crew is dead set on getting George in that lifeboat, never mind the hundreds of other innocents on board. When they discover George has died, the crewmembers turn on Jim, wishing their buddy were in his place on the lifeboat. His death makes everything worse for Jim, both during the Patna incident and in life back on shore.