Vendaval translates to "gale" or "strong wind." It's a more dramatic and less common word than simply "viento" (wind), making it stand out.
In the song, it describes a sudden, powerful storm that threatens the singer's boat. This word perfectly captures the unexpected challenge and the need for a strong "capitán" (captain) to navigate through life's difficulties.
Juan Luis Guerra turns a small fishing boat into a shelter from the storm. He sets out to sea ("Salí en mi botecito a navegar" — "I went out in my little boat to sail"), rod and guitar in hand, until a gale and then a shark threaten to capsize him. Each time danger rises the chorus answers with the same anchor: "Jesús está en el bote" ("Jesus is in the boat"). Even a cyclone ("si viene el ojo de un ciclón" — "if the eye of a cyclone comes") can't sink him, because the captain steering him through it isn't a sailor — it's his faith. Merengue horns and that call-and-response "En el bote" ("In the boat") hook turn a personal testimony into an irresistible dance track.