If you don't mind tolls, take the Cape May-Lewes Ferry to Lewes De. . Pick up 113S South Follow truck route 9 around Georgetown De. to get there, then at end of 113S pick up 13S across the Chesapeake Bay Bridge Tunnel. After the tunnel follow 13 to 64 to 264 through Norfolk. Pick up 58 on south side of Norfolk to 95S, then follow 74 in SC to Myrtle Beach. Not the fastest route but no too bad traveling.
The fastest way would be head west from the shore to 295, then pick up 95S to SC, then take 74 in SC to Myrtle Beach.