I am searching for a hentai comic(pic unrelated).
The comic involves this girls who are like part battleship. And they are fighting this unstoppable horde of evil "ships". They kidnap one girl and drag her down into the ocean. They manipulate and corrupt her until she becomes one of them.
The evil ships have large EVA style teeth and that's about all I remember about it. Any help would be great. Thanks!
almost certainly a kantai collection doujin.
dunno which one you're specifically talking about because the scenario you describe happens pretty often in them
but you should have enough information now to tag search nhentai and other sites and just browse until you find the doujin you're looking for