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Fear of violation guides oily water separation technology use

Shipboard oily water separators are internationally mandated as engine room equipment and are intended to allow engine room crews to clean engine room bilge water prior to discharge into the world’s oceans. This equipment was mandated based on the assumption that uncleaned discharge of engine room bilge water would result in discharge of oil to the environment. It has never been clearly established if oily water separators actually work to a level that enable crews to operate them in a reliable fashion. — Society of Naval Architects and Marine Engineers (SNAME), 2005


The International Convention for the Prevention of Pollution from Ships (MARPOL) was developed in response to the major oil spills caused by the wrecks of the oil tankers Torrey Canyon in 1967 and Amoco Cadiz in 1978.

MARPOL Annex I came into force in 1983. That regulation stated that the discharge of oily water mixtures is prohibited by all vessels except if it is processed through oil filtering equipment from which the cleaned bilge water doesn’t exceed 15 parts per million of oil.

Annex I also sparked a new industry: the design and construction of oily water separators. But if the oily water separators didn’t function as advertised, as SNAME hypothesized prior to its study 10 years ago, then many vessels were at risk for violating MARPOL rules.

If a vessel, whether a container ship or a yacht, was found in violation of MARPOL, what could happen? According to the MARPOL Training Institute, “(a) vessel may be detained, the owners/operators fined and placed on probation, and the involved crew member may be imprisoned and/or fined. Many companies have been fined millions in U.S. dollars for MARPOL violations worldwide.”

Scary stuff if you are an engineer on a charter yacht or a cruise ship.

Hendrik Van Hemmen, the author of the SNAME study, concluded that his assumption was true.

“Despite numerous (but often disorganized) efforts, shipboard bilge water oily water separation systems fail to produce satisfactory results for owners, regulators and crews. The failure of these systems is not solely related to technical equipment design issues, but reaches back into human factors, systems design, record keeping methodologies and inspection procedures.”

Fast forward to 2015, and these same oily water separation systems issues have yet to be resolved. In fact, it is such a continuing hot topic that the National Fish and Wildlife Foundation, a non-profit organization founded by the U.S. Congress, recently hired Van Hemmen to conduct a six-month study on the continuing problems with oily water separators.This most recent study included a survey of crew members responsible for operating the oily water separators. One said, “People are scared of the possibility of fines/jail time for violating accidentally. A lot of time, the oily water separator is not run out of fear. Teach everyone how to properly use and care for one.” Another commented, “Crews are in an absolute panic for even documentary mistakes as they believe they will be viewed as criminals even if the mistake is genuine or minor.”

Clearly, there is still much work to be done. So much so that the major stakeholders (the cruise ship industry, the offshore oil industry, the deep water commercial vessel industry and the regulators) met in June to discuss the recently completed study. Their goal was to come up with best practice solutions to this ongoing problem in machinery spaces.

Once the results of this conference are disseminated, they will filter down to the yachting industry and hopefully make the job of the yacht engineer a little less stressful.

Capt. Jeff Werner has been in yachting for more than 20 years on private and charter yachts, both sail and power. He is an instructor for RYA, MCA, USCG and US Sailing courses and owns Diesel Doctor ( Comments on this column are welcome at

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One thought on “Fear of violation guides oily water separation technology use

  1. Chief Engineer

    I have over 10 years in yachting.
    I have never needed to use a oily water bilge separator.
    I have ALWAYS had problem getting different kinds of bilge separator to work right away/flawlessly.
    I disslike OWS

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