The development and utilization of the "underwater backhoe," a multifunctional underwater construction machine

The rubble leveling that accompanies the base mound construction for breakwaters and embankments takes place in demanding underwater environments involving extremely high risks. There is also concern about labor shortages and aging of divers. Moreover, harbor development sites have extended farther offshore in recent years, making it necessary to cope with more treacherous weather and deep-water conditions. Under these circumstances, in efforts to ensure safety and to shorten the process by speeding up operations, the demand for a safe underwater construction machine that can perform such tasks has been growing. In response to such demands, the "underwater backhoe", which mechanizes manual work performed by divers, has been developed. The device excels at tasks such as armor-stone leveling and rubble leveling required for base mound construction for breakwaters and embankments. This paper provides a background of underwater backhoe development and presents an overview of existing backhoes. It also introduces several instances of use in underwater work and considers several problems and areas for improvement.