Be Watchful of Shipping Emissions Below Waterline!


  • The global maritime industry is making significant progress in the fight to reduce ship greenhouse gasses.
  • But it should not lose sight of what’s going on below the waterline.
  • The issue was raised in the World Ocean Council (WOC).

Speaking in Barcelona on the first day of the WOC’s Sustainable Ocean Summit, Thordon’s Vice-President of Business Development said: “There are today a number of initiatives looking at reducing emissions above the waterline, but not so many looking at preventing pollution below the waterline. This can be part of global policies to improve our oceans and seas under the United Nations’ Sustainable Development Goals, Number 14 – Life Below Water.”

Focus On Blue Economy

“To further advance ocean sustainable development and put to sea truly zero-emissions ships, then we really do have to get rid of the oil-lubricated shaft line and replace it with one lubricated by seawater. From well to wake, the environmental impact of an oil-lubricated stern tube needs serious consideration.” Carter said when answering a question raised during the Sustainable Ports and Shipping for the Blue Economy session. 

According to numerous environment data sources, Carter estimated conservatively that leaks from the global shipping fleet’s propeller shafts resulted last year in more than 60 million gallons of oil polluting the world’s seas and oceans. While damaged and worn stern tube seals contribute massively to the constant flow of oil into our seas and oceans, a research paper carried out last year by Linnaeus University’s Kalmar Maritime Academy concluded that stern tube seals are not at all leak free, with oil leakage considered “normal” operating conditions.

Exploring Alternatives

Carter went on to explain that the advancements made in elastomeric polymer materials over the last decade not only offer a viable environmental and economic alternative to the oil-based system but seawater-lubricated shaft lines can also figure in the shipping industry’s CO2 emissions abatement plans.

Initial research suggests that because a seawater-lubricated propeller shaft system operates with lower friction coefficient (resistance) compared to one operating oil-lubricated white metal bearings, less fuel is required to propel the vessel, resulting in a small but nonetheless important reduction in carbon emissions.

The Sustainable Ports and Shipping for the Blue Economy discussion followed keynotes from Simon Bennett, General Manager, Sustainable Development, Swire Shipping Pte Ltd., and Jordi Vila Martinez Head of Environmental Department, Autoritat Portuària De Barcelona.

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Source: Thordonbearings


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