We are cruising in the Med and can only speak English, but in every country we try to learn at least enough words to be polite (please, thank you, hello, good bye, etc.). More important is to use the words you know and to ask for help with pronunciation and then to ask for help with other words and the names of things. People everywhere are willing to help you learn their language when you make an effort.
Even though you can get by with English in many places, learning French and Spanish will only help. We are spending the winter in Spain and are taking Spanish classes, but the best way to learn is go speak with locals at every opportunity.