I thought the answer to 23d was big dipper ( group of the seven brightest stars in ursa major also known as charles's wain ) however think 29a imperial unit of dry measure equal to one quarter of a bushel is PECK,.This does not fit with big dipper.
also puzzled by 22a ) arrangement of the sails and other rigging on a ship or boat . I have EQUUS for 15d and I cannot find a term for 22a which is S - B.