In Illinois, it is illegal to both operate cars and boats while under the influence of alcohol. But, these crimes are listed in separate places in the Illinois Compiled Statutes. The law that applies to boats is located in the Boat Registration and Safety Act. The exact citation is 625 ILCS 45/5-16. The law that applies to cars is in the Illinois Vehicle Code. The exact citation is 625 ILCS 5/11-501.
With either offense, a normal first offense is a Class A misdemeanor. An OUI under the Boat Registration and Safety Act will not affect a person’s driver’s license, but it may affect a person’s ability to operate a watercraft.