After the second episode on Tuesday night 778 complaints had been received.
The screenwriter Emma Frost said the opening instalment on Easter Monday was like "listening through mud". After reviewing irate comments on twitter, she turned off the computer in frustration and reached for a glass of red wine.
Viewing figures also fell from 6 million initially to 4.5 million for the second episode. But there was praise for the performances and the authentic look of the series.
The story tells the tale of Mary Yellan, who is taken in by her brutal uncle Joss and his terrified wife Aunt Patience after her mother dies.
She stumbles across a group of murderous wreckers who take down ships and steal their loot in early 18th century Cornwall.
Jessica who took the lead role was fascinated by her character's bravery. "The thing that struck me immediately and was really refreshing is that it was a story where the lead was a heroine, a woman," the actress told the Telegraph.
"But you could just as easily give her a male name and the story could stay the same. It's not just fluffy, girly, boring stuff."
The young star refused to wear make up for shooting so that her look was more authentic and spent hours in the freezing sea.
She told the Mirror that filming in the Atlantic was "ridiculous". "It was exhilarating and special because you were able to get to a place so far beyond where it feels 'pretend'. It was real and there was a certain level of fear."
Lifeguards were on hand at all times, but that didn't stop her being scared. "You were in the sea, everyone disappeared and you may drown," she added. "The waves were so big - you'd go under and you couldn't see which way was up".