For the improvements on dredging efficiency by a suction hopper dredge, the idea of the use of leveling blades attached to the both side of draghead war considered. Then, the model dredging tests have been carried out on the use of leveling blades attached to draghead in Port ahd Harbour Research Insitute. Through the tests, the basic dredging characteristics such as dredging configuration, dredging concentration, drag force and flow pattern of dredged materials around the draghead were mainly investigated. The result on the studies was issued already.
　This time, another study on the model tests which will be applied for KAIHO MARU owned by the fourth Port Construction Bureau was performed. In this case, several kind of blades of which position to the draghead are varied respectively were used and the dredging tests with double tracks were also carried out.
　Through the tests, the influences of the blade's position on the general dredging characteristics similar in the former works for each blade were mainly investigated. And, herein, the leveling effects by the special draghead with wide double inlets are also described together with the partial introduction on the newly signed wide draghead with multi-suction-holes.