Rare Plumb Bob, Carved Wood to Simulate a Narwhal Tusk, 19th Century Consign Now DeptDecorative Arts, Maritime ArtsSize83 in. x 7 ½ in. Rare Plumb Bob, 19th Century, carved wood to simulate a narwhal tusk, used to stabilize load in the keel of the sailing ship. 83 in. x 7 ½ in. Please note that this auction has ended. Click here for an overview of this auction.