The French were recovering from their losses in the Seven Years War by the 1780s. To state they were dominating anything is a bit of a stretch- it would be more accurate to say they had raised themselves to being a significant threat. De Grasse’s fleet that helped at Yorktown was defeated in 1782 in the Caribbean: http://en.wikipedia.org/wiki/Battle_of_the_Saintes
Ah. Thanks.
I concur that the French were not a dominant fleet at the time. Fortunately, de Grasse got into the Chesapeake before the British and he had superior numbers. After the British were roughed up they went back to New York and returned with a bigger fleet - arriving two days after the surrender.