"DEAD SPOTS by William C. Martell Is your story going somewhere, and is it getting there? One of the main ... Every scene in your script should be there for a reason. No dead spots. Keep it sailing along. - Bill"
I was struck by exactly the same thing but I think that the mistake is even more egregious that you suggest, because there's a whole lead- in to there ending up on Galapagos (I think they actually go there briefly once and then have to return there a second time which, as far as I can see is probably two times too many).
That's because, having established this desperate drive to seek out this French ship, at a certain point, the Doctor is accidentally shot on board ship and I thought Oh, great, now, with his best friend just shot and the only person capable of treating any of the wounded, including himself, now down for the count here is the perfect time, dramatically, for the bad guy to show up.
But no. Instead, they decide that this is the perfect time for the main character to decide to give up the chase, because, apparently, without a doctor to treat the wounded, he doesn't feel that he can effectively fight this French ship so back he goes to the Galapagos where they can effectively treat the Doctor on dry land.
Then, with all of the air out of the sails they've given up the chase, the French ship is presumably gone, now the Doctor is getting better and out of the blue here comes the French ship.
But at this point it's like who cares? It's obviously no longer a threat, and the guy who was so obsessed about chasing it had essentially quit so yes, it's now wandered back into range and now they'll go after it again but big deal.
That is, if the test of the drama is you have duty on the one side and personal issues on the other what is this man willing to give up in order to do his duty the lives of his crew, their respect and now it comes down to the life of his friend. Nope. Won't give that up. Bye bye, duty, we're heading back to the Galapagos.
And that's the point. He's made the critical decision of the story when he gives up the chase to save his friend's life.
And frankly, within the context of the story it's a shitty decision. He should continue the chase. Duty should clearly take precedence.
So it isn't only that the air goes out of the story dramatically, because nothing is moving the story forward, it also goes out of the story *thematically* because the fundamental issue what is at stake duty vs. friendship is resolved. He's made his choice and then along comes the ship and he figures out some little trick and manages to catch it, but again so what? It all comes, in a sense, after the key decision.
It's almost as if Rick arranges for Ilsa to go with Victor Laszlo, and they get away and then the movie goes on for another fifteen or twenty minutes before there's a final showdown with the bad guy Nazi.
Who cares? The key issue would already have been resolved.
NMS