The Playwrights Realm is presenting this intriguing new play by Anna Ziegler at the Peter Jay Sharp Theater. Sarah (Miriam Silverman), a social worker in her early 30s, and Sam (Matt Dellapina), a budding musician, have been a couple for several months. Their quiet Christmas Eve at Sarah’s apartment is interrupted by a sudden knock at the door. The uninvited guest is Nate (Nick Westrate), Sarah’s close friend since childhood. Bearing champagne and weed, Nate insinuates himself into their evening. Sam and Nate have neither met nor heard of each other before. Nate is an intensely self-centered overgrown child, filled with existential dread that the world existed before him and will go on after him. He has longed for Sarah since childhood as the only person who can save him and has showed up that night to persuade her to choose him. Like Icarus in Breugel’s famous painting, he fears that his suffering may go unnoticed. Each character breaks the fourth wall periodically to tell the audience about previous as well as future events. The urge to please one’s parents is a theme that recurs. The title comes from the image of time as a ship delicately navigating the shoals between past and future. The events of that evening have a profound effect on all three characters.The actors are all excellent, the set by Reid Thompson is evocative, the costumes by Sydney Maresca are fine and the direction by Margot Bordelon is smooth. The playwright is not always in full command of her material, but shows considerable promise. Running time: 75 minutes, no intermission.