The Kullenberg corer (Kullenberg, 1947; Kelts et al., 1986) is a single-drive, cable-deployed piston corer that is dropped into the sediment from a short distance (typically 0 to 3m), propelled by the momentum of the heavy (~1000 pounds/450 kg) lead weights on the core head. Cores are recovered in steel barrels lined with plastic tubes (standard polycarbonate for the LacCore system). The corer drop is triggered when a gravity corer, suspended on a second cable to the side of the Kullenberg corer, enters the sediment and ceases downward travel—thus most Kullenberg cores have an accompanying gravity core that captures the upper sediments that are disturbed by the long corer. Deployed from a cable, the range of water depths is limited only by the length of cable on the winch. However, the immense weight of the system requires a substantial secondary apparatus to handle the corer. A heavy-duty winch and hydraulic system or power supply must be employed to raise and lower the corer, and if long core barrels are used to increase the depth of recovery, a tower or A-frame must be available for deployment and recovery. The weight and bulk of the system can also create hazardous conditions in any deployment circumstances, but particularly if waves cause the vessel to roll and pitch. Thus, a minimum of two experienced crew plus three additional hands is required for safe operation.
The LacCore R/V KRKII is a large platform consisting of two 19-foot (5.5m), 950-pound skiff boats bolted together with aluminum deck plates and beams. It can be disassembled and towed behind a heavy-duty truck or shipped in a standard 20-foot shipping container. It was engineered and custom-built for Kullenberg coring, for which it provides a large, stable work surface, a 6.5m quad-leg tower, and 5m long moonpool. At 6m long and 5.5m wide, it is larger and heavier than is necessary for most other types of coring operations, and it is more difficult to ship and requires more time to assemble than more appropriately-sized platforms.