: A realtime Augmented Reality binocular for the assistance of nautical staff is presented. AR systems combine the real environment with additional information. Nautical sea chart data is used to superimpose information into views with a magnification factor of 7 which cause a big effect on directional errors in the augmentation. We discuss the system requirements and present an analysis of the hardware components. The detection of the actual position is done without a magnetometer but using a gravity sensor in combination with an image-based marker tracking approach. It will be shown, that very high accuracies are achievable for the localization of real objects.