From the Missouri Water Patrol site, I know you can drink a beer but you have to be under the level if stopped. Make sure that county doesnt have a open container law. A six pack over several hours wont get ya a ticket unless you slammed them, then the fishing must really suck if you slam them.
It's the Law: On the Water With Your Vessel
Alcohol and Drugs-Zero Tolerance!
Missouri law prohibits boating while intoxicated—that is, operating a vessel while intoxicated due to alcohol or any combination of alcohol, controlled substance, or drugs.
Missouri law states:
It is evidence of intoxication if a person has a concentration of alcohol in his/her blood of 0.10% or more, based upon a chemical analysis of breath, blood or saliva.
Missouri law establishes the following penalties:
Those convicted of boating while intoxicated are guilty of a class B misdemeanor upon a first conviction. In addition, those convicted will be required to complete and pass an approved boating safety course.
Upon a second conviction, a person is guilty of a class A misdemeanor.
Upon a third or subsequent conviction, a person will be guilty of a class D felony.
A person boating while intoxicated who causes the death or serious injury of another person will, upon conviction, be guilty of a felony.
By operating a vessel on Missouri waters, you have consented to be tested for alcohol or drugs if requested by a law enforcement official. If you refuse to be tested, you will be subject to arrest and punishment consistent with the penalties described above.
Missouri’s laws affecting boating while intoxicated are referred to as BWI. But, don’t forget, Missouri also has laws affecting driving while intoxicated—DWI. Effective September 29, 2001, Missouri’s blood alcohol concentration for DWI was lowered from 0.10% to 0.08%. Although any level of impairment may result in charges of DWI, a BAC level of 0.08% or above is prima facie evidence of intoxication under Missouri law. While the BAC level didn’t change for BWI, it is important to remember that if you drink enough while boating to raise your BAC level to at least 0.08%, as soon as you get off the boat and begin to drive your car, you can be arrested for DWI.