With high signal availabilities, capable/robust receivers, and well-populated satellite constellations, GNSS users typically believe that the output of their receiver is correct; however, the increasing existence of inexpensive L-band hardware has some of these users concerned with the integrity of the derived location and time information. Of interest here is spoofing in the maritime domain, in which counterfeit GNSS signals mislead a GNSS receiver into reporting an inaccurate position or time; a typical concern is malicious spoofing that convinces a tanker entering or exiting a harbor that it is off track of the channel. A variety of approaches have been proposed to recognize spoofing, some based on the RF GNSS signal alone while others compare the GNSS information to measurements available from non-GNSS sensors. Toward this latter approach, the ION literature provides several examinations of the use of non-GNSS signals for spoofing detection; examples include IMU data, radar (range and bearing) data, range data alone, and pseudoranges. At GNSS+ 2018 two of these authors proposed methods to use bearing information (as provided by an alidade) to detect GNSS spoofing. At that same GNSS+ 2018, another of these authors presented results on a bearing-based positioning system, BinoNav R , that makes use of a modernized pelorus to work with a modern bridge. The current paper marries the ideas from these 2018 beginnings, attempting to combine the spoof detection concepts with BinoNav’s level of performance and ease of use. We focus our efforts on pairs of simultaneous non-collinear bearing measurements so that all spoofing events are observable and an analysis of performance is possible.