The United States Coast Guard (USCG) uses navigational buoys to direct water traffic and to protect vulnerable benthic ecosystems such as seagrass communities and coral reefs in U.S. waters. However, most buoys are currently attached to the seafloor by concrete anchors, also called sinkers, and heavy metal chains that can have just as significant an impact on marine life themselves. Sinkers can damage life on the seafloor under their heavy footprint, and when the connecting chains are lax, they can scrape off seagrasses, seaweeds and corals around the sinkers as waves and wind push the buoys around.

USCG has been struggling to find a solution for more than 20 years, and the service reached out to the Department of Homeland Security (DHS) Science and Technology Directorate (S&T) for help. Through a prize competition in January 2016, S&T received proposals for solutions from across the country as well as the international community.

Among them was a proposal from Cole Keaoulu Santos, an innovator from Hawaii, for a simple yet effective buoy mooring system. Instead of a concrete sinker, he proposed a narrow screw anchor; instead of a heavy metal chain, he suggested an elastic rope to prevent scraping of the ocean floor.

In April, the USCG Research and Development Center (RDC) embarked on a two-year experiment to test several different types of mooring systems inspired by Santos’ concepts. Using USCGC Joshua Appleby, a 175-ft. Keeper-Class coastal buoy tender, RDC deployed five buoy mooring systems near the coast of St. Petersburg, Florida. There, the buoys’ impact on the ocean floor and ability to withstand the elements while staying securely moored will be evaluated. The results will determine if the moorings are fit to be adopted on a broader scale.

Eco-Mooring for Species Protection

Using helical anchors and elastic mooring lines is not new. Recreational boaters have been using the concept, called eco-mooring, for some time. Coral reefs and seagrasses are among the most biologically diverse ocean ecosystems; they provide important habitat for marine life—manatees, sea turtles and a variety of fish and invertebrates. An environmentally sensitive mooring system can help preserve these ecosystems.

In April 2018, USCG installed two types of anchors at water depths of 38 to 48 ft.—the traditional concrete sinker and the helix (screw). Three types of mooring lines are being used: StormSoft, Hazelett and Supflex. For the experiment, they chose two navigation channels with a bare sandy floor suitable for the helix anchors.

For the next two years, USCG will visit the buoy moorings every three months to monitor their durability. The dive team will document the condition of each mooring line and will provide photographic and video evidence. When the testing period is over, USCG will prepare a final report of the eco-friendly buoy moorings to support future decisions.

Department of Homeland Security, Science & Technology Directorate