Figure 4. Percent solids by weight versus time

ERDC TN-DOER-I4

August 2000

The production meter on the Thompson consists of a Texas nuclear densimeter and Doppler

flowmeter. Outputs from these instruments are connected to a display on the bridge and to the DSS.

The SI work unit provided a serial interface module for the production meter to allow it to send

digital density and flow data to the DSS. The DSS computer sends out data to the Ship Server over

another serial port, but it also stores the data within the DSS.

Data Analysis and Reporting. The raw data are available for visual inspection (Figure 4) and

quality assurance purposes. Manually reviewing the raw data is too time-consuming for inspectors

to perform on a regular basis, however.

Figure 4. Percent solids by weight versus time

The SI can produce some of the summary data that are now reported by manual methods. Table 1

shows a comparison between some manual daily report data from the dredge Thompson and the SI

computed ones. These data were taken between September 29, 1999 and October 4, 1999 at

Savanna Bay (River mile 538.5, Rock Island District) on the Mississippi River. The Thompson's

cubic yards per hour are derived from survey data, the effective time from the daily logs and the

distance advanced from the DSS. The SI uses the observed pumping time to compute the effective

time, the cubic yards per hour are computed from the production meter, and the distance advanced

is computed from the DSS-provided horizontal position data.