There are a lot of languages where ships aren't intrinsically feminine, like for example old english where they were neuter. You should be able to test your hyp

There are a lot of languages where ships aren't intrinsically feminine, like for example old english where they were neuter. You should be able to test your hypothesis by seeing whether those languages still associate ships with goddesses? Though IMO the goddess connection itself needs validation. For the second part, about assigning connections after the fact, something I always found weird and interesting is french ship gender conventions. The ship has the gender associated with the name it carries, but the name itself is chosen to match the gender of the underlying form. eg a fuel carrier is masculine and so will get a male name and pronoun, a frigate is feminine and will get a female name and pronoun.