Thursday, September 24, 2009

River Tenders—aids to navigation on the Western Rivers

Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine. By LCDR Jerry Davenport, U.S. Coast Guard.

The Coast Guard’s inland river tenders, while conceivably the most unrecognized part of the organization’s afloat community, play a vital role in maintaining safe navigation throughout the Western Rivers.

Inland vs. Coastal Aids to Navigation
Coast Guard river tenders service and maintain the nearly 10,000 buoys and 4,000 fixed shoreside aids that assist those navigating the waters.

Each river system is unique and requires a variety of operational standards. For instance, on the Ohio River, buoys are typically positioned using smaller river-type buoys (6th-class buoys), with moorings of 1/2-inch chain and 1,500-lb. sinkers. On other rivers, buoys may be positioned using moorings of wire rope with concrete sinkers, or they may be jetted or pushed into the river bottom. On rivers like the lower Mississippi River, larger river-type buoys (4th-class buoys) with 3/8-inch wire rope and 1,500-lb. sinkers are used.

While coastal and inland waterways are marked for safe navigation by the lateral system of buoyage, coastal buoy tenders have transitioned to the use of differential global positioning systems to set buoys and use a very precise automated aid positioning system software program to calculate and record buoy location. Inland river tenders operate on the extreme outer limits of a channel to mark the maximum safe navigational channel, considering channel alignment, prevailing river stage, and obstructions.

Inland river tenders determine the best navigable channel by using a depth finder to ascertain the channel and surveys provided by the U.S. Army Corps of Engineers. Because of the ever-changing and unpredictable environmental conditions associated with the Western Rivers, buoys are not assigned positions.

Another notable difference is that Western River buoys and day boards are not numbered, since they don’t have assigned positions. However, the river fixed shoreside aids have placards or “mile boards” to help show the river mile location.

Typically, a coastal buoy tender might work five buoys a day, with each buoy taking up to two hours to service. It takes longer to determine the assigned positions of the aids, and the buoys are usually larger, making them more difficult to handle. An inland river tender can service a significantly larger number of buoys a day—perhaps up to 100—spending only a couple of minutes on each aid, verifying that a buoy’s last position still marks the navigable channel, replacing missing buoys, or resetting the channel. A typical day for an inland river tender consists of replacing or repairing numerous buoys and making frequent stops to maintain and service fixed shore aids along its area of responsibility.

Multimission Platform
In addition to its primary aids to navigation responsibility, each inland river tender is also a disaster response and homeland security platform. It is also common practice for inland river tenders to serve as command platforms for various events. In this capacity, the vessel serves as the command and control platform, providing vital communication links among the participating federal, state, and local agencies.

Within the homeland security mission area, every time an inland river tender gets underway, it is conducting a maritime domain awareness patrol. Aboard armed vessels capable of protecting valuable waterways assets, the river tender crews constantly analyze the surroundings with an emphasis on understanding all elements of the maritime environment that could impact security, safety, or the economy of the United States.

An Aging Fleet
The majority of inland river tenders are 40-plus years old. Over the last several years, the number of catastrophic machinery failures has increased tremendously. It has also become increasingly difficult to find replacement parts to effect timely repairs. This leads to additional costs and extended repair times, placing greater stress on the remaining fleet that must spend more hours underway to ensure service intervals are met and waterways properly marked.

Although some progress has been made over the years, the inland river tenders need to be updated and replaced. The Coast Guard has recognized many of the challenges associated with the existing inland river tender fleet. In fact, the organization has chartered several working groups to address many of these issues.

Several groups are focused on providing the most fruitful short-term options to bridge maintenance gaps and extend the lifespan of the existing vessels. Other groups are looking at long-term solutions. One can be assured that these groups are committed to ensuring continued availability of inland river tenders and timely maintenance of the navigational system until a long-term solution is achieved.

About the author:
LCDR Jerry Davenport has served in the Coast Guard since 1980. He has served various cutters and shore units and has 13 years of experience at units within the Western Rivers.

For more information:
Full article and “U.S. Coast Guard Western Rivers Sectors” edition of USCG Proceedings is available at Click on “archives” and then “2007-08 Vol. 64, Number 4” (Winter 2007-08).

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