Answer: There is no Federal Law that we are aware of and you would need to check with your local and state authorities to see if they have one.
Safety would dictate some judgment needed here and if there is an appearance of danger a voyage could be terminated. An example would be high speed and waves, wakes, or obstacle's that would cause a sudden turn of the boat that could cause a person to fall in the water and possibly be severely injured or even killed by the boat's propeller.
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