The following Florida statutes apply to driving under the influence"
"316.193 Driving under the influence; penalties.—
(1) A person is guilty of the offense of driving under the influence and is subject to punishment as provided in subsection (2) if the person is driving or in actual physical control of a vehicle within this state and:
..."
"316.003 Definitions
...
(97) VEHICLE.—Every device in, upon, or by which any person or property is or may be transported or drawn upon a highway, except personal delivery devices and devices used exclusively upon stationary rails or tracks."
Thus, a boat is not a vehicle and therefore Section 316.193 doesn't apply. I don't see a comparable criminal statute regarding operation a boat under the influence of alcohol, but to be sure you might ask a police officer or sheriff's deputy.
