OAK BLUFFS, Mass. — “Please return to your vehicles,” the ferry attendant announced over the intercom. “We are approaching the terminal.” I dusted off powdered doughnut residue and left the circular snack bar as the boat crossed the Vineyard Sound.

My first vacation on Martha’s Vineyard was bartered. Jessica B. Harris, the culinary historian, English professor and writer, needed eyes for the drive up from New York, and hands, to unload multiple pieces of luggage and white plastic shopping bags filled with pantry items and Swedish red licorice.

In return I would stay in Dr. Harris’s pink-trimmed cottage in Oak Bluffs. Between the pale blue hydrangea bushes of that storied neighborhood and the shoreline of the Inkwell, a historically African-American beach on the island, I met seasoned black Vineyarders whose screen doors swung open in time-honored hospitality.