YA Historical Fantasy book set on a boat about a Vampire captain and a human girl. Read 2009-2015.

[Daisy]

I read this book between 2009 and 2015. The book itself and the way the story was told didn't seem old so it was published at most a few years earlier than that.

The story had a dark aesthetic but it was clearly written for teens/YAs. It was set on a boat and not in the modern days, probably 17th or 18th century.

The female protagonist was 16-19, the male protagonist was a little older than her and the captain of the ship. I'm almost sure that the male protagonist and the boat crew were vampires (I know the female protagonist was human but everybody else was not).
I don't remember how the story started but i remember the heroine was stuck on the ship. I’m not sure if she was a prisoner or she was rescued after a shipwreck or something different, but i remember that she didn't board the boat willingly and could not get out even though she wanted to. I vaguely remeber that at least at the beginning she was locked in a cabin for her own safety, otherwise the other vampires/boat crew would have killed her to drink her blood.
There was some conflict between the protagonists but they fell in love. I remember that they knew that their love was wrong or their relationship was forbidden.

I’m not sure about the following details at all but I think I remember a purple eye on the cover and that the author had an “english-sounding” name (the version of story that i read was translated to another language).

[Ayshe]

Demons of the Ocean maybe?