A method for correcting position error in a navigation system enables one to more accurately match a position measurement of a moving object on a digital map. Since the storage requirements are calculated to select a storage destination volume for each file, data storage destination optimization can be achieved on an individual file basis. The piston further includes a plurality of radially arranged, spaced-apart tensioners that stretch the seal into sliding engagement with the interior surface of the tank. The heads up display may be configured to be controlled by a remote controller, e.