In the US a vehicle drivers license
to operate a boat is not required. What will happen is the his boats insurance
rates will rise possibly making it cost prohibitive to insure his boat.
In my mind there is a correlation between the two. If he is willing to drive a car intoxicated then he is probably just as likely to operate a boat intoxicated. Possibly even more so since many people think there are no penalties for operating a boat intoxicated.
No offense, but I have no sympathy for buzzed or drunk vehicle or boat operators. I have just seen or read about too many alcohol related injuries or deaths, on the water
especially. Some of these people I used to know.