What has been said so far is correct, HOWEVER, be aware that in France, if you being investigated, and cannot prove that you are paying income tax elsewhere, the 183 days residency allowed comes down to 4 months.

In practice, yotties -large or small- are rarely investigated. In the early nineties the authorities wanted to crack down on the wealthy yachts berthed in up market Riviera marinas. These boats simply left these ports for Italy. The immense loss in business that followed soon encouraged a change of heart and they then returned.

For example, it was pointed out to me recently that the annual bill for flowers for one such yacht is more than my boat is worth!