Figure 8. Weeks Marine dredge positioning system (with ranges, CL, and dustpan positions annotated)

R375

R-375

Dustpan

Figure 8.

Weeks Marine dredge positioning system (with ranges, CL, and dustpan positions annotated)

a. With any dredging position with an approximate range R > +100 ft, the

deep-draft vessels could pass with no interruption to dredging because

just the cross-channel wire was dropped to allow the vessels to pass.

During the time the wire was dropped, there was no significant decrease

in production noted on the density meter (usually 2 to 4 min long for one

passing vessel). The length of time required to release tension on the

cross-channel wire and drop it to the bottom was less than 5 sec.

b. Given the volume of deep-draft vessels passing during the demonstration

(in 6 days 143 vessels with drafts greater than 20 ft passed), the

Beachbuilder could not dredge in the negative range (LDB) side of the

channel for a continuous interval longer that 1 hr 45 min. The number of

deep-draft vessels passing during the demonstration was estimated to be

slightly below average (as per communication with Captain Michael

Lorino, President of the Mississippi River Bar Pilots Association).

Chapter 4

Dredging Operational Characteristics Analyses