The Oxy Trader, a 42,260-dwt liquid bulk carrier, was the first of three integrated catamaran tug-barge (Catug) vessels built by Avondale Shipyards, Avondale, La., for Occidental Petroleum Corporation.
The vessel is designed to transport highly viscous, dense and corrosive superphosphoric acid (SPA). Many other bulk liquid products also can be transported.
Designed by Hvide Shipping and its affiliate, Seabulk Corporation, the Catug is an integrated tug/barge (ITB) that combines the efficient hull form of a ship with the wide-beam, shallow-draft characteristics of an oceangoing barge. Tug and barge sections were constructed separately and are designed to be employed as an integrated unit.
The design utilizes a twin-hull catamaran tug with a propulsion and steering system in each hull to increase its safety and reliability. It is reportedly more maneuverable than a single- or twin-screw ship. The tug and barge may be separated rapidly in case of emergency.
Other benefits inherent in the design include lower capital costs and substantially lower manning requirements than conventional ships, all resulting in markedly reduced financial and operating costs.
The Oxy Catugs are powered by two 9,100-bhp Colt-Pielstick, 14-cylinder direct reversing engines, one in each hull. Each engine drives a four-bladed, 20-foot-diameter, slow-turning propeller. Each power unit has its own separate rudder and steering mechanism. A service speed in excess of 15 knots has been achieved.
Built to ship scantlings with heavy reinforcement for the very dense SPA cargoes, the Oxy Catugs have an SPA carrying capacity of 40,100 metric tons at a draft of 36 feet. The five SPA tanks are located in the center of the barge; they are clad with 3,17L stainless steel.
Each tank is equipped with heat exchangers drawing steam from two waste heat boilers in the engine uptakes or from a separate boiler plant on the barge. This maintains the SPA at a temperature above 150°F while in transit. Hydraulically operated submerged pumps are capable of discharging all cargo tanks to less than four gallons within 20 hours. Tanks are cleaned by hot fresh water washing via a portable Butterworth system.
Ten wing tanks are coated with water-based inorganic zinc, and may be used to carry petroleum products. The vessel also is fitted for protectively located segregated ballast. The unique design permits the Catugs to carry a wide variety of other liquids — clean and dirty oil products, and liquid chemicals.
OXY TRADER
Main Propulsion ... (2) Colt-Pielstick Reduction Gear ... Colt Industries Propeller ... Harvey Shaft ... National Forge Co. Bearings ... Service Foundry Generator Engines ... Boyce Machinery, George Engine Steering ... Sperry Marine Pumps ... De Laval, PRP Industries, Goulds Pumps, Colt Industries Air Compressors ... Colt Industries, Service Engineering Sanitation ... Red Fox Industries Tank Cleaning ... Butterworth Crane ... Schat Davit Corp. Winches ... Marine Safety Equipment Windlass/Capstan ... New England Trawler Co.