Abstract: First and second inclinometers are mounted above the deck of a ship at different distances from the ship's center of gravity. Each inclinometer generates a signal in response to the angular movement of said ship with respect to the true vertical. The difference between the signals is multiplied by a factor which is proportional to the ratio of the distance from the higher inclinometer to the center of gravity to the distance between the inclinometers. This product is then subtracted from the electrical signal generated by the higher inclinometer resulting in a signal which is proportional to the roll or pitch angle of the ship.