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SECO Helps Shrimp Trawl Fishery to Reduce Fuel Costs

SECO has an Interagency Agreement with Texas A&M University’s Sea Grant College in the amount of $124,769.00. The objective of the one year contract is to evaluate and document three innovative gear technologies within the southeastern shrimp trawl fishery that reduce fuel use and/or increase revenues. Sea trials will be conducted to demonstrate the usage of new gear technologies, as compared to traditional methods. The results of the sea trials will be disseminated to shrimp fishermen. The three areas to be reviewed are:

1)  Evaluations of New Tech Fiber
Fuel-saving modifications for shrimp trawls do exist. One such modification is the substitution of nylon webbing with newer, proprietary “high-tech” fibers. During the 1990s, with funding from the State of Texas Energy Conservation Office, Texas Sea Grant was instrumental in demonstrating and evaluating Spectra® webbing (manufactured by Allied Fibers, Inc.) aboard shrimp trawlers in Texas. These demonstrations were later expanded to other geographic locations within the Gulf of Mexico. Spectra® webbing is far superior to nylon webbing because at equal breaking strength, it has a smaller diameter and reduced weight. As a result, a 10 to 15 percent benefit in fuel efficiency was clearly demonstrated.

However, one perennial disadvantage of Spectra® webbing is price. Since 2002, this has become a more acute issue because of growing demand for personal body armor due to the Iraq and Afghanistan conflicts. Because of growing demand, the current per-pound price for Spectra®, has dramatically increased from $28.00 to over $40.00. Although a number of vessels have historically utilized Spectra® webbing, current production economics suggests that industry cannot afford this material at current price levels. New lower priced alternative fibers on coming onto the market. This project will demonstrate the value and energy efficiency of a new fiber.

2)  Cambered Trawl Doors
Additional methods to reduce fuel consumption within the shrimp industry are being tested in Texas. A Texas company has been evaluating the use of cambered (i.e., slightly curved), slotted oval-shaped trawl doors that have been employed in other trawl fisheries outside of the southeastern United States. Trawl door design has evolved significantly over the past decades, but until recently has not received attention in the southern shrimp fishery. Evaluations of these doors suggest that they offer significant promise in reducing fuel consumption in the shrimp fishery. This project will document any fuel savings by using a new trawl door design.

3)  Skewed Propellers
One of the most significant applications that the shrimp industry has adopted for greater fuel economy has been the installation of propeller nozzles on many offshore trawlers. The use of nozzles is not new to the industry, as this application became a common practice in the late 1970s. Several vessels have installed skewed propellers in conjunction with nozzles, and have claimed various degrees of fuel efficiency. The skewed propeller array is designed to reduce excitation level force, which in turn creates greater hydrodynamic efficiency. This information has been poorly documented in the shrimp industry and a need exists to document the effects of a skewed propeller inside a nozzle system upon fuel consumption. To do so, a suitable vessel equipped with a nozzle will be selected for evaluation of the skewed propeller. Initially, through use of a fuel flow meter, fuel consumption rates with the traditional propeller will be documented. The skewed propeller will be then be installed and fuel utilization rates will be recorded, both during towing and running. Vessel speed, both during running and towing, will be standardized for comparative analysis of the different propellers.

For more information about this project, please contact the SECO Program Manager, Marvin Barr, at marvin.barr@cpa.state.tx.us.

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