What is it called when a boat operator deliberately puts a person or property at risk?

Negligent Operation.

operating a boat in a reckless manner is negligent or grossly negligent operation of a vessel and is against the law. If it interferes with the safe operation of the vessel, and endangers lives and property the Coast Guard may fine the operator with a civil penalty for negligent operation.

Grossly negligent operation is a criminal offense and an operator may be fined up to $5,000, or jailed for up to a year, or both.