From the Windstar website under General Information:
"If you’re dining in Amphora, Stella Bistro, or Cuadro 44 by Anthony Sasso in the evening, slacks or non-distressed jeans are appropriate, paired with collared, button-down or polo shirts, or fashion tops or blouses. Skirts with nice tops, casual dresses and sundresses are also good choices. Dress shoes, nice sandals or stylish athletic casual shoes round out your evening wardrobe. Depending on your destination you may wish to pack shorts, hats, flip flops and t-shirts, but please reserve them for your daytime activities."
We did Wind Surf for 17 days in the southern Caribbean and dress for dinner was as listed above. My hubby & I, along with another couple, are booked on Wind Spirit for Sep 7 to Sep 18.