Even in protected waters, triple anchoring to hold station is usually necessary for vibracoring. Ship traffic, when working at anchor, can be an inconvenience if not a hazard even for a properly marked vessel. Deployment of anchors or marker bouys may be restricted in shipping lanes. Crews should always remember that waves from passing boats can arrive at inopportune times during coring. In industrial harbors, limited access through untended bridges, if not prearranged, can cause major delays. Low profile or collapsible coring rigs can be a big advantage in such harbors. In busy northern ports, off-season coring through the ice (with a boom truck rig) may be an alternative.
Core profiles of harbors sediments (periodically dredged) are often chaotic, with confusing inversions of older and newer materials. Less "sensible" core strata should be expected and are not necessarily a matter of vibracoring technique.