April 1983 - Maritime Reporter and Engineering News

MarAd Feasibility Study On Oceangoing Dry-Bulk Self-Unloaders In U.S. Trade

Use of oceangoing self-unloading vessels in the U.S. dry-bulk trade is feasible, under certain conditions, according to a report released by the Maritime Administration.

The study, "Use of Self-Unloaders in U.S. Dry-Bulk Commerce," was prepared by COR, Inc., Falls Church, Va., for Mar- Ad.

The report discusses a new method established to define and evaluate measures of merit and effectiveness for different sized self-unloaders. It reviews unloading equipment in the Great Lakes to predict performance characteristics of conceptual oceangoing self-unloaders, as well as cost, weights, and operational characteristics of most modern onboard equipment.

Selection of ship size is a major concern of the maritime community.

Although larger ship sizes generally may result in lower transportation costs, especially especially in the bulk trade, physical route constraints, capacity of loading and receiving terminals, and ship hydrodynamic characteristics frequently counterbalance effectiveness.

The researchers concluded that U.S. use of oceangoing selfunloaders is economically feasible under certain conditions and sets of operational factors. These include the length of voyage, ship size, terminal dimensions, and loading and discharging rates as well as cargo availability and physical characteristics.

The most economically sized vessel for trans-Atlantic operations and in routes in the Mediterranean, according to the study, is a 100,000-dwt self-unloader.

The vessel would have a beam of 134 feet, a draft of 45 feet, and an overall length of 850 feet.

It would be powered by twin, slow-speed, direct, reversible diesel engines with twin-screw propulsion.

Using self-unloaders could considerably reduce port delays and lead to increased vessel performance, the study found.

Copies of the 370-page report are available from the National Technical Information Service, 5285 Port Royal Road, Springfield, Va. 22161. The order number is PB83-161331; the price is $29.50.

Other stories from April 1983 issue


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