An apparatus for manually maintaining the level of a radar antenna mounted on a stern pole affixed to the deck or transom of a vessel providing a platform pivotably mounted to a distal end of the pole and oriented to rotate about an axis substantially parallel to the centerline of the vessel. A controller at the lower end of the pole proximal to the cockpit permits manual adjustment of the horizontal angle of the radar antenna to maintain level due to heeling of the boat. The controller utilizes a first plate secured to the pole having a series of detent positions angularly spaced around and equidistant from a center point and a second plate rotatably secured at the center point. A grip handle projecting from the front surface of the second plate permits rotation of the plate when a cooperatively aligned release handle is grasped to withdraw one or more pins extending through holes in the second plate engage the detent positions. A pair of cable or rod linkages transmit rotation of the second plate to the antenna mounting platform.