Why Accusative: O, miseros nautas....

In LLPSI cap. XX Orberg has Aemilia say:

O, miseros nautas, qui numquam domum revertentur! O, miseros liberos nautarum, qui post hanc tempestatem patres suos non videbunt!"

Clearly she’s not addressing the nautae nor the liberi and so they could not be in vocative case.

But why accusative?

..and why especially when they are both the subject of the sentences (that end in passive verbs)?

Does the exclamation ‘O!’ take accusative the object which follows…? That would seem the most likely reason to me.

“Miseros nautas!” = “What wretched sailors!”

Yes indeed, accusative in exclamations! Ita quidem, exclamationis est accusativo casui servire.
just as in “Silly me!” // sicut “Me miserum!”

Have you seen this dedicated forum to LLPSI?
http://discourse.textkit.com/t/lingua-latina-per-se-illustrata-by-h-orberg/10138/1

Yes. So what! There is nothing helpful there on this topic.
Iterum. Quid meâ refert? Nihil ibi est quod hanc rem spectat.

And now you are spamming the forum by saying the same thing in multiple places. :confused:

It’s not spamming to try to restore sense to a thread in responding to a spam. Nor am I repeating myself in any way.
Saginationem non spargo qui epistulae tuae respondendo sensum fili reducere tenem. Nec alterutro modo me repeto.