Increasingly, hydrographic offices are turning to robotic, unmanned, and “autonomous” surface vehicles (ASVs) to conduct systematic seafloor surveys for hydrographic applications (nautical charting). The term “autonomous” is set in quotes to acknowledge the spectrum of capability of these vessels, which varies from those that are remotely piloted (but possibly either manned or unmanned), to those that have some auto-pilot capability, to those that have the ability to react to their local environment, for example to avoid hazards and other ships while optimizing data collection. Data on which these reactions are based may be provided to them or sensed on their own.

The practice of hydrographic survey is categorically different from general navigation of transiting commercial vessels whose operation may fall under other guidance. Hydrographic survey involves the systematic ensonification of the seafloor, usually in “lawnmower” patterns whose lines extend along contours of constant depth. During survey, launches do not often follow prescribed or traditional transit lanes but often operate within those lanes. Survey launches may operate in tandem or independently, covering separate areas within a region; their base of operations may be on shore or a parent survey vessel. 

This document seeks to provide a set of best practices for operation of ASVs conducting hydrographic survey, and whose operations are focused on this unique application. The intent of this document is to propose guidance for safe operation and good seamanship based on real-world experience and by complying with the intent of the Rules set forth by the 1972 International Regulations for the Prevention of Collisions at Sea (COLREGS)1 and other provisions that may be in force in U.S. or other State regulations. In a few cases, recommendations made here may conflict with existing regulations, either because those regulations do not explicitly address autonomous systems or because in our experience the capabilities of autonomous systems, and the expectations of other mariners, are such that additional caution is warranted. Organizations should augment or modify these recommendations to ensure safe operation and comply with regulations as necessary.