( CNN ) -- After more than 12 hours stuck at sea , passengers aboard a whale-watching boat off the Massachusetts coast reached shore and safely docked in Boston on Tuesday morning , the Coast Guard said . The 163 people aboard the Cetacea found themselves stuck after a line got tangled in the vessel 's propeller Monday afternoon , the Coast Guard said in a statement . The 83-foot boat was about 13 miles ( 21 kilometers ) east of Nahant , Massachusetts . On Tuesday morning , the line entangling the propeller was released , Coast Guard Petty Officer MyeongHi Clegg said . The boat docked at the Long Wharf in Boston , Clegg said . Three Coast Guard crews had been on the scene , with one vessel offering medical support as needed . Clegg said two people had become sick , but their illnesses were not considered serious . Coast Guard members and Boston Harbor Cruises conducted checks to ensure the boat 's safety before it headed back to shore , Clegg said . The Coast Guard vessel Tybee helped escort the boat .
NEW : The stranded boat safely arrived at the Long Pier in Boston . The boat was five miles east of Boston , Massachusetts . It became stuck after a line tangled in its propeller .