Unless laws have changed -- and maritime laws generally don't -- the boat making the wake is liable for all damages caused by the wake, from broken docks, to spilled drinks, to death. The basis for the law is wake damage to banks of canals -- its been on the books for centurys. So was it really a wake, which boat caused it, and when does that owner pay for the damages?
By the way -- if the owner does not pay up, and sells the boat, the new owner is liable. Yup, that's how maritime law works -- its the boats fault, and remains the boats fault until completely paid.