Death in Rough Water — Francine Mathews

It wasn't easy for Detective Merry Folger to convince her father, the Nantucket police chief, that she had the right stuff. But with her first murder case neatly behind her, Merry proves she's a third generation any cop would be proud of. Still, she has orders to leave this one alone...

A DARK AND STORMY NIGHT
When Captain Joe Duarte slid from the deck of his fishing trawler and disappeared into the black waves, everyone agreed his death was an accident. Everyone, that is, except Joe's estranged daughter Del, whose return to Nantucket with a baby has fueled the local gossip. Del never named the baby's father, and never reconciled with Joe, but now she's convinced that her father's been murdered and begs her childhood friend, Detective Merry Folger to track down a killer. What Merry trails is a wake of fishy stories, threatening letters, scandalous secrets...and some murky motives for a watery death.