This MSIB is issued to provide awareness for the upcoming Gulf Menhaden seasonal event. Some of the inherent risks to vessels that use sea strainers include loss or reduction in propulsion, reduced maneuverability, and loss of water pressure within the firefighting systems.
Loss or reduction in propulsion continues to occur in the Houston Ship Channel (HSC) complex. One of the causes continues to be accumulation of small fish in vessels' sea strainers. This is typically a seasonal event involving primarily Gulf Menhaden, with May-October being the highest risk (although vessels have reported encountering Menhaden in their sea strainers year round). Gulf Menhaden are found in coastal and inland tidal waters and form large surface schools, appearing in near-shore Gulf waters. Schools of fish are drawn into the vessel's sea chest clogging the sea strainers, reducing cooling and causing high water/oil temperatures. In extreme cases, these fish have choked entire coolant systems resulting in engine auto slow down or automatic shutdown. Any system that takes suction from the sea could be at risk at any given moment due to the narrow waterway and the draft of vessels creating very high density of schooling fish in the water column.
The Lone Star Harbor Safety Committee's Causality Analysis Workgroup (CAWG) developed a feedback form titled "Vessel Questionnaire on Cooling Water Impacts by Menhaden Fish" which deep draft vessels are again asked to complete and submit to email@example.com. The data collected will assist the CAWG with its continued analysis of the patterns of the Menhaden and the development of additional best practices.
Recommended Best Practices:
1. Sea chests should not be used without filter strainers in place and should be monitored at all times in the HSC.
2. Detailed procedures for cleaning seawater strainers should be established. These procedures may include back-flushing or regular changing and cleaning duplex strainers as appropriate.
3. Prior to transit, inspect and clean the service sea chest. Ensure filters and coolers are clean prior to entry into U.S. waters. Implement a preventative system that requires frequent cleaning and swapping between sea strainers.
8. Consider implementation of an engineering-designed approach, such as using the aft peak tank for seawater cooling purposes or internal cooling, which is commonly used for vessels which operate in extreme cold weather conditions such as the Baltic Sea and Great Lakes during the winter.
This bulletin shall remain in effect until April 1, 2021.
K. D. ODITT
Captain, United States Coast Guard
Captain of the Port
Enclosure: (1) Menhaden Identified Best Practices and Menhaden Questionnaire
Menhaden Identified Best Practices