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6/11/2018: Three Marine Safety Alerts – High levels of hydrogen sulfide gas; water slides aboard commercial vessels; Gulf Coast vessels and blended fuel oils

The Office of Investigations and Analysis issued three Marine Safety Alerts to warn mariners of several potentially dangerous conditions that vessel owners, operators, and captains should be on the lookout for.

Marine Safety Alert 08-18 shares important information and recommendations related to a unique, not very well known and potentially deadly hazard that recently developed on a vessel involving the formation of dangerous levels of Hydrogen Sulfide (H2S) gas within a waste oil tank. This was determined to be due to the use of biodegradable cleaners and the chemical reactions and resultant H2S byproduct involved in breaking down oils in an anaerobic (low oxygen) environment like that found in a full slop tank. In this case, vessel officers had detected significant H2S concentrations (>200 PPM) in the vessel’s engine room bilge holding tank. This circumstance had existed for quite some time as crewmembers had previously reported smelling the distinctive odor of rotten eggs in the vicinity of the slop tank, which is an indicator of the gas.

Marine Safety Alert 09-18 offers tips surrounding the installation of water slides onboard commercial vessels sometimes characterized as “party boats.” Coast Guard inspectors investigated two recent casualties in which passengers using the slide contacted the vessel’s aft rail and sustained severe bone fractures. Slides much like those commonly used at pools offer an element of fun during hot days on the water. Besides commercial vessels they are also found installed onboard private boats, rental house boats, and rental party barges. The Coast Guard does not regulate the installation or usage of these slides, but reminds owners, operators, and captains of any vessel with a slide that they have the responsibility to ensure the overall safety of their vessels, passengers, and crewmembers. If a slide installation appears to present unnecessary risk, actions should be taken to minimize the dangers to those persons who may use it.

Marine Safety Alert 10-18 seeks to raise awareness of a significant emerging problem in the U.S. Gulf Coast region regarding contaminated vessel fuel oil bunkers and the use of blended fuel oil such as Intermediate Fuel Oil (IFO 380). These fuels have been known to cause fouled fuel pump plungers, fuel pump seizures and other fuel system related failures. Furthermore, the fuel may increase sediment levels at separators and fuel filters and, in some cases, may completely clog filters. The standard fuel oil test methods found in the ISO 8217 specification will not detect these underlying problems. The Coast Guard recommends that vessel owners and managers ensure vessel operators are made aware of this potential hazardous condition, closely monitor fuel oil system components and consult their bunker suppliers and other technical service providers regarding this issue.

These safety alerts are provided for informational purposes only and does not relieve any domestic or international safety, operational or material requirement. Developed and distributed by the Office of Investigations and Analysis. Questions may be sent to

This blog is not a replacement or substitute for the formal posting of regulations and updates or existing processes for receiving formal feedback of the same. Links provided on this blog will direct the reader to official source documents, such as the Federal Register, Homeport and the Code of Federal Regulations. These documents remain the official source for regulatory information published by the Coast Guard.

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