Delays may become common on the Hatteras-Ocracoke ferry route because shoals that have been building since Hurricane Irene in August have forced to state to begin using small vessels for crossing Hatteras Inlet.

The state Department of Transportation said Friday that tides also may require ferries to take fewer vehicles on some runs so the vessels will ride higher in the water, and they may cancel some runs.

Maintaining shipping channels is up to the U.S. Army Corps of Engineers. NCDOT said state and federal officials are working on a memorandum of agreement that has to be in place before dredging can begin.