306.220.  Personal flotation device, who must wear, when, exception, penalty. — Each person under the age of seven who is on board any watercraft which is on the waters of this state shall wear a personal flotation device which is approved by the United States Coast Guard.  Any person who allows a person under the age of seven to be on board any watercraft which is on the waters of this state without wearing a personal flotation device shall be deemed guilty of a class C misdemeanor.  This section does not apply when the person under the age of seven is in a part of a watercraft which is fully enclosed, where such enclosure will prevent such person from falling out of or being thrown from the watercraft.