New findings reveal that synthetic EALs lead to higher rates of stern tube seal failures

Thordon Bearings, a pioneer in seawater-lubricated bearings, has welcomed the publication of Gard’s research into the potential hidden costs of synthetic Environmentally Acceptable Lubricants (EALs). The research points to a significant increase in propeller shaft aft seal damage following the 2013 introduction of new Vessel General Permit (VGP) rules by the US EPA. According to Gard, the increase in seal failures directly correlates with the use of approved synthetic lubricants in compliance with US EPA regulations.

Gard’s research, published in October 2023, found that as many as 80% of the incidents investigated involved stern tube seal failures where an EAL was in use. Thordon Bearings’ VP of Business Development, Craig Carter, emphasized that seawater alone is the only 100% pollution-free means of lubricating a ship’s propeller shaft bearing. The research suggested that the chemical composition of synthetic EALs, while environmentally preferable to mineral oils, is typically inferior in performance.

The Thordon COMPAC system eliminates the need for the aft seal, reduces friction, diminishes fuel burn and main engine emissions, and provides improved bearing wear life, predictability, and reliability while offering lower maintenance costs, easier installation, and future-proof compliance. Thordon’s findings align with Gard’s research, which underscores the importance of seawater as the most environmentally acceptable lubricant. The research also highlights the potential environmental consequences of using synthetic EALs and the benefits of seawater-lubricated propeller shaft bearing systems.

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