To sail or enjoy the coast in a stylish and retro way, a striped t-shirt, jersey, pullover etc is required. The king of all striped combinations is that made up of navy blue and white, which is sharp and very nautical. White trousers (or jeans if you want), blue boat shoes or loafers, and Wayfarers complete this 50s-60s Mediterranean coastline look. Below are 2 examples of the modern and urban approach to the European nautical look.
And if you're already in a nautical spirit, I recommend you watch today "A Plein Soleil", the original 1960 version of "The Talented Mr. Ripley" starring Alain Delon. Great film especially if you're into the Italian late 50s /early 60s style.