I can’t wrap my head around some sentences in this chapter.
First of all the verb praefero confuses me. Here’s line 83:
Dixisti enim ‘te mortem servituti praeferre’."
It feels like it means “For you said ‘you prefer death to slavery’.”, but I’m not quite getting the grammar here. Does the “preferring something to something else” come from the fact that praefero is paired with a dative (servituti)?
If so, would the captain himself have said Praefero mortem servituti?
And what would it look like if I simply preferred one thing, like apples? Would they be in the accusative or dative case? (Praefero mala/malis?)
My next question concerns line 99:
Fortuna adversa amicis fidendum non est!
My gut feeling says it means “Friends should not be trusted in hard times!” But again the grammar is confusing. Fortuna adversa is in the ablative case, and I guess amicis is a dative and fidendum a gerundive. The gerundive form suggests a nominative or accusative. But I do not understand why the gerundive would take any of those forms. What are the connections here?
I think you understand the use of praefero here. Praefero means to put something before another thing and according to L&S to prefer (very frequent).
So the usage is Praefero aliquem alicui and your version of the captain’s words seems correct to me, although in fact he said it in a roundabout way.
“And what would it look like if I simply preferred one thing, like apples? Would they be in the accusative or dative case? (Praefero mala/malis?)”
I think you can only prefer one thing to another (or to many things). “I prefer apples” is an idiomatic English sentence which is the same as “I like apples”. I dont think praefero works the same way as English prefer. This is a good question to raise because it raises a translation problem. Translating from English to Latin you have to think what the words actually mean before you translate them. What you translate is the idea not the word.
Possibly “I prefer apples” might contain a suppressed comparison. If you said it while you were looking at a fruit basket the thing you were preferring the apples to would be clear. Or it could mean I prefer apples to all other fruit. I think you would need to make all this clear in your Latin translation.
I will deal with your other question later unless someone else answers it.
Thanks, now I have a better understanding of how the verb works. It also makes sense to not assume that the Latin praefero works exactly the same way as the English prefer. 
Looking forward to receiving help with the next question.
Fortuna adversa amicis fidendum non est
So the ablative Fortuna adversa is the time “at which” so “in a time of bad fortune”. amicis is datve plural and the indirect object of the gerundive " fidendum non est" which I take to be a neuter nominative singular and the construction is impersonal.
“in times of bad fortune do not place your trust in friends” , (it is not to be trusted in friends - remember that the gerundive is passive. ) Generally speaking in translating Gerundives into English it’s best to tun the passive into active voice.
This is explained in the following sentence. Namque amici, quos in rebus secundis multos habere videmur, temporibus adversis nobis desunt. Because friends , whom we seem to have many in favourable times, in difficult times fail us.
Its late I hope this is clear.
Ah, seems that I was on the right track. But I didn’t understand that fidendum non est was an impersonal construction. Thanks again!
I hope if wasn’t insomnia that kept you up at 3AM btw.
Thanks for your concern!
I decided it was better to try and answer your question before I went to bed. It was 2 am not 3 I think we are in different time zones.
yes you were on the right lines with both questions. 