MS Plan B Defense: A Navigation System to Enable Real-Time Relative Positioning at Sea

Matthew Feeley 
Master’s Student
Department of Ocean and Resources Engineering
University of Hawai’i at Mānoa

**This defense will be held in-person only  at Holmes 287

Oceanographic research conducted by unmanned robotic swarms demands spatially precise coordination of vessels. Although research in position control of autonomous vessels has advanced, it is challenging to acquire relative positioning guidance at sea without committing significant resources toward vessel modifications or new equipment. This paper presents an overview of NarwhalNav, a navigation technology designed to make relative positioning data more accessible. NarwhalNav integrates a GNSS receiver, radio and software into a mobile package for rapid deployment on any vessel.

NarwhalNav tracks the inter-vessel distance and relative bearing between a leader-vessel and a follower-vessel as they drive in formation. The NarwhalNav application software continuously compares position coordinates from each vessel to calculate inter-vessel distance using the latitude and longitude values measured by the mobile package. To rigorously assess the accuracy of NarwhalNav, onshore and sea trials were conducted. Onshore tests established a baseline for the system’s accuracy in calculating inter-vessel distance. That performance was later compared to a demonstration in a harbor. Within the harbor, two vessels equipped with NarwhalNav sailed together in a leader-follower formation, and a rangefinder verified the inter-vessel distances optically. Despite captains’ efforts, maintaining a uniform distance between the vessels proved more difficult than expected, and as a result, rangefinder measurements varied by ±21 ft. Under these conditions, the system achieved an accuracy of ±10 ft. These findings provide a roadmap for the future development of NarwhalNav, focusing on enhancing robustness, communication range, and seamless integration with unmanned platforms.