Elizabeth Spann Craig 
Cruising for Murder [EPUB ebook] 

When Myrtle and her friend Miles set out for adventure on the high sea, they assume most of the trip’s excitement will result from shore excursions to charming Alaskan villages.
They feel as if their ship has come in. But when a fellow passenger disappears, Myrtle realizes she must seize the helm and find the killer…before more souls are lost.