Collaborating to Mitigate Risk: The tools that guide the process.

Excerpt from U.S. Coast Guard Proceedings of the Marine Safety & Security Council magazine by LCDR Tony Maffia, visual navigation signals management policy manager, U.S. Coast Guard Visual Navigation Division; Mr. George H. Detweiler, Jr., marine transportation specialist, U.S. Coast Guard Marine Transportation Systems Management Directorate; and Mr. Burt Lahn, marine transportation specialist, U.S. Coast Guard Marine Transportation Systems Management Directorate.

The United States Coast Guard Office of Marine Transportation Systems Management develops and implements policies and procedures that facilitate commerce, improve safety and efficiency, and inspire dialogue within the maritime community to make our waterways safe, efficient, and commercially viable.

One way we do this is by establishing risk baselines that guide our decisions. Three tools that guide these efforts:

• ports and waterways safety assessments,
• waterways analysis and management system studies,
• port access route studies.

Ports and Waterways Safety Assessments

The Coast Guard established the ports and waterways safety assessment process to address waterway user needs and place a greater emphasis on partnerships with industry. The process involves convening a group of waterway users and stakeholders and conducting a structured workshop to elicit their opinions.

Waterway Analysis and Management System Study

Our nation’s waterways contain more than 100,000 aids to navigation—the buoys and beacons that provide signals to maritime transportation system users. A waterway analysis and management system study helps Coast Guard waterway managers review and improve the system in a particular waterway. The study incorporates the perspectives of major and/or frequent waterway users to identify the most effective aid mix while anticipating needs for the future.

Port Access Route Studies

Permanent structures such as oil rigs and offshore renewable energy installations may affect port traffic, and areas like designated marine sanctuaries also must fit into this mix.

To manage this, the Coast Guard may create traffic separation schemes. Through the port access route study process, the Coast Guard consults with affected Native American tribes as well as federal, state, and foreign state agencies (as appropriate) and considers the views of maritime community representatives, environmental groups, and other interested stakeholders.

Port access route studies continue to identify critical changes in maritime traffic volumes or routes, and allow the Coast Guard to implement sound vessel routing measures to ensure safe passage in the off-shore approaches to our nation’s ports and harbors.

Full article is available at http://www.uscg.mil/proceedings/spring2011/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.

Offshore Renewable Energy Installations: Impact on navigation and marine safety.

Excerpt from U.S. Coast Guard Proceedings of the Marine Safety & Security Council magazine by Mr. George H. Detweiler, Jr., marine transportation specialist, U.S. Coast Guard Marine Transportation Systems Management Directorate.

To reduce our dependence on foreign energy supplies, alternative or renewable energy sources are being pursued. These sources exploit a wide range of technologies:

• solar photovoltaics or power plants;
• hydroelectricity (dams);
• ocean thermal energy conversion facilities;
• offshore renewable energy installations, which may include “wind farms,” marine current turbines, and wave generators (hydrokinectics).

All these technologies have the potential to affect marine navigation and safety, and although no offshore renewable energy installations presently exist in U.S. waters, several are contemplated following successful trials in other countries.

Of the technologies being considered, wind farms and hydrokinetics pique the Coast Guard’s interest because their developers propose to locate them in U.S. navigable waters.

Navigation Impact

All offshore installations, regardless of type, will have impact on vessel navigation and safety in their vicinity.

Location. An offshore site could affect navigation based on the traffic volume, types of waterway users, and other vessel characteristics such as speed capability, navigation equipment, and number of passengers.

Spacing. To make best use of the wind, turbine spacing is proportional to rotor size and the down-wind wake effect created. As such, wind farm turbines are generally spaced 500 meters or more apart.

Visibility. These structures could also block or hinder the view of other vessels, the coastline, or other navigational features such as aids to navigation, landmarks, or promontories used by mariners to navigate.

Electronic impact. Larger structures could produce radio interference with respect to any frequencies used for aviation, marine positioning, navigation, or communications, including automatic identification systems.

Effects of tides, tidal streams, currents, seabed changes. Current maritime traffic flows and operations in the area of an offshore renewable energy installation are affected by the depth of water in which the installation is situated at various states of the tide.

Additionally, the structures themselves could cause changes in the set and rate of the tidal stream or direction and rate of the currents. Also, structures in the tidal stream could produce siltation, deposition of sediment or scouring, and other suction or discharge aspects, which could affect navigable water depth.

Mitigating the Impact

While these offshore renewable energy installations have many potential benefits, it’s important to recognize the equally potential negative effects mentioned and to devise plans to mitigate them.

The Coast Guard will review the assessment to develop a “safety of navigation” opinion and associated mitigation measures that it will forward to the appropriate lead permitting agency.

Full article is available at http://www.uscg.mil/proceedings/spring2011/.

Subscribe online at http://www.uscg.mil/proceedings/subscribe.asp.