The crane fell off a crane at the Cavan Harbour Marina, about 100 kilometres south-west of Co Dublin, on Saturday night.
The crane was carrying a crane operator to a crane shop in the harbour and was about to be transported to the site when it was struck.
The operator of the crane was taken to hospital for treatment.
The area around the crane, in the Cian Dail, is an industrial zone with a number of major industrial facilities and a number the company uses for training.
The company has been operating under a contract for the past six months.