Cómo eran mis compañeros muertos en el mar

Cómo eran mis compañeros muertos en el mar
 

Hi,

Estar muerto - ser un muerto is a classic Spanish student problem :)

Still, I am not sure how I'm supposed to translate the title into English...

To be dead - To be a dead person
The first one is the state of the person and the second one defines what they are.

But... How my comrades died at sea? Really? Why?

I uploaded it to the ReversoContext:

Cómo eran mis compañeros muertos en el mar

How were my dead companions at sea

Does not make a lot of sense, just as I expected :)

estar muerto = to be dead
ser un muerto = to be a dead person
ser muerto = to be killed

Fueron muertos en manos del príncipe. = They were killed by the prince.

I think the example in your title is the 3rd usage. Something like this:

Cómo eran mis compañeros muertos en el mar = How my companions were killed at sea

Why not Fueron muertos a manos del principe?

@Tyrn: "En manos del príncipe" and "a manos del príncipe" mean the same, in this context.

@Tomísimo: "Cómo eran mis compañeros muertos en el mar" means I'm going to tell what my old mates were like. They all died in the sea, either because of natural disasters, diseases or any accident that could have killed them. The author uses "ser", because he/she is describing their personalities and his/her relationship with them when they were alive.
If the author were telling how they were killed, he/she would have used the verb in preterite: "cómo fueron muertos en el mar". ;)