9-6. Dreger

The assembles of the dredges used during KR98-08 Cruise are illustrated in the figure showing main wire, wire leader, heavy chain (with attached heavy weight and small pipe dredge), fuse wire (with attached parallel life wire) and the main chain-bag dredge. Main wire is installed winch wire of the R/‚u Kairei for scientific observation. It is piano wire of 14 mm diameter, 12000 m long, 0.815 kg weight per one meter.

Wire leader was prepared for protection against damage to the main wire and was joined by shackle to the main wire. It is steel wire of 14 mm diameter, 200 m long. Heavy chain is used to stabilize the dredge assemblage and was joined to the wire leader with a 3 ton swivel and shackles. Weights were moreover linked to the heavy chin to add additional stability and provide additional possible sampling. The weight is used to assure the dredge is on the bottom as can be observed by the tension meter in the operation room, and was linked by shackles to the heavy chain together with a swivel, fuse wire and life wires. Small pipe dredger serves both as a stabilizing weight and common small dredge. It was also linked to the heavy chain. Fuse wirewas prepared to release the dredge from big bites that might damage the main wire. It was jointed to the heavy chain with a swivel and shackles in the both types of dredge assemblages. One end of the life wire is connected parallel with fuse wire(s) and another end is linked with one winding at the upper middle part of the chain-bag. The life wire is designed to close and recover the chain-bag dredge with rock samples secured in the lower part of the chain-bag in the case all fuse wires are broken by a big bite or anchoring.

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