The lack of metrics to assess clamshell formation dredgeability limits the ability of engineers to predict the dredgeability of compact material and increases the risks associated with clamshell selection. Work done and motor energy are possible dredgeability metrics that can be estimated using micro-processor based machine monitoring. The objective of this work was to test the hypotheses that work done by the pistons during dredging, by ahydraulically actuated dredge, is a better predictor of clamshell dredgeability than motor energy. The research hypothesis was tested by comparing the measure of uncertainty surrounding mean estimates and the coefficient of variation. From this work, it can be concluded that work done is a better predictor of formation dredgeability than motor energy. Copyright © 2011 Inderscience Enterprises Ltd.