I was trying to figure out whether I should be sinking or boarding ships and I read one post that said ships are now spawning infinitely. Any truth to this? I tried scouring all the patchnotes but I didn't see that  mentioned.

Yes. Ships will respawn infinitely. But only the first generation will have unique captains. The following ones will have a generic name. For example if you sink Chornu and his Early Muster he will be replaced by an "Unexperienced Rauatai Captain" or something along those lines.

Some captains are so unique that they will not respawn a ship in their place (for example Fyrgist of the Black Isle Bastards or Myrlesfen the Truly Insane on his Ironclad). Mostly it's the four factions' ships that respawn: VTC, RTC, Huana and Principi.

Here are the patch notes (4.0 - first point). 

Edited September 20, 20196 yr by Boeroer

Nice, thanks. Now I feel a little better about just choosing whatever strikes my fancy in the moment, without worrying about missing out.