Last summer, when he was 80 years old, Jock Williams completed the 2,700-nm Down East Loop in a Stanley 36, a boat that he built in his own yard in Maine. Now, Williams says he’s ready to go cruising again, although he’ll have to wait for the coronavirus pandemic to end. Williams, who owns the John Williams Boat Company on Somes Sound on Mt. Desert Island, is no stranger to cruising. (He’s on the right in the picture above, with Reg Elwell, a cruising companion.) Williams grew up on Martha’s Vineyard, joined the Navy after graduating from Colby College, worked…