USS Shepherd Knapp (1861) was a large (838-ton) ship with eight guns, purchased by the Union Navy during the beginning of the American Civil War. With her eight guns and a crew of 93, she was employed by the Union Navy as a heavy gunboat outfitted to pursue major Confederate States of America blockade runners, especially Confederate Captain Raphael Semmes. Her limited ability as a sailing ship in pursuit of steam powered adversaries was eventually recognised and a different strategy adopted. She became a decoy, disguised as an unarmed merchant ship sailing in areas where Confederate raiders were known to operate.