噴射式 桁網의 開發에 관한 硏究 - Ⅱ

Development of Hydraulic Jet Dredge - Ⅱ

To catch the surf clam. Mactra chinensis, in sand bottom using the excavating performance of water jet, the authors had constructed the experimental hydraulic jet dredge by the result of water tank experiment of previous report, and also were carried out the field experiments in the surf clam fishing ground near Kunsan, Korea from 5th to 30th of october, 1990. The results obtained are as follows. 1) Excavating depth was more than 10-11cm at the 1500cm/s water-jet velocity in the fine sand and muddy sand. 2) Towing tention was only 105±5kg in the 6.7cm/s towing speed. 3) Average catch amount per unit towing area was O.42kg/m²and it was 1.2-1.6 times comparing on the conventional dredge. 4) Experimental hydraulic jet dredge did not nearly brake the surf clam. 5) Turbidity variation by the water jet of dredge was not serious in the fishing ground; On the surface, when the depth is more than 5.2m, thrbidity variation was not found at all, and on the 3m layer above the bottom, turbidity variations was increased 9-11ppm at 1m backward from the dredge, but it was gradually decrease, and it was nearly not at 9m backward from the dredge.