The backhoe is a large crane based on a bucket digger. It is mounted on the end of a pontoon that has been fitted with spud posts. The backhoe can dredge a wide variety of materials, including debris, rock and soft, weathered or broken rock. PUMA has deployed a backhoe to remove the bottom-most layer of stones in the existing Maasvlakte block dam. The average length of a backhoe is 50 m.