An assembly for connecting a support element to a bone. The coil having a plurality of windings about an open core, the winding support extending through the open core. The erratic motion device can be constructed and programmed to produce a wide variety of erratic, random and unpredictable movement in the removable decoy shells for attracting the wildlife. In one embodiment, one or more of the independently formed partial ring sections is placed on the exterior of the tubular to form a well completion. The actual error phase and the phase component of the polar signal are used to generate a corrected phase component which is applied to a further mapping unit forming part of a phase modulating unit. In yet another aspect, current aquatic effort data and prior aquatic effort data are utilized to obtain another anchor point for a watercraft.