Thordon Bearing Applied To Articulated Rudder

When a 9,280 hp. workboat returned to service following extensive repairs at the James Marine Paducah River Service yard in Kentucky, it marked the first application of Thordon’s new seal-embedded bearing to an articulating rudder.

Articulating rudders are unlike conventional rudders and can be more costly to repair when things go wrong. They are more susceptible to wear and tear, due to their higher operating pressures and abrasives, and as a result, they require a more robust bearing and seal solution.

For one marine transportation service provider in the United States, however, a key requirement was a grease-free bearing capable of increasing the intervals between drydockings and reducing operational costs.

To meet the requirement, Thordon engineers recommended a bearing using the company’s proven ThorPlas-Blue material, a better material for articulating types of rudders, and integrating a Thordon lip seal into the design.

“We found that by embedding a lip seal into the bearing, we could better prevent ingress of river water, sand, silt and debris, which would otherwise rapidly wear the pins and bushigs down, reducing the workboat’s in-service time,” said Kasey Cummings, technical sales manager for Thordon Bearings.

The workboat operator needed this type of rudder to do what it was designed to do–reduce fuel costs. However, frequent drydockings for rudder bearing replacement were eating into any fuel savings. With a fleet of more than 50 linehaul vessels and 800 dry cargo barges, the operator’s fleet transports more than 40 million bushels of grain each month, so fuel savings can really add up.

“The new design certainly optimizes the operational and cost efficiencies associated with an articulated rudder,” Cummings said.

Thordon introduced the design back in 2020 and installed the 3.149-inch-diameter bearing in March 2021. This was the first workboat reference for the new seal-embedded bearing and the first time that ThorPlas-Blue was used in the flap portion of an articulating rudder. Thordon has since supplied 60 bearings for an additional 15 articulating rudders installed on other workboats operating in the U.S. inland waterways.

As part of a comprehensive engine and propulsion overhaul, Thordon’s robust bearings were also installed to the 168- by 45-foot  vessel’s rudder flaps, main trunk and pivot pins. In total, 16 ThorPlas-Blue bearings were supplied and fitted.

Cummings continued, “ThorPlas-Blue can handle three times the operating pressures and forces of other bearing materials used on the inland waterways; however, for inland waterway vessels operating articulating rudders, we do recommend machining flap bores to facilitate the installation of the ThorPlas-Blue bearing seal combination.”

Cummings said the installation was very straightforward; the only modification was to the rudder flap pins. Yard staff added a chamfer on the leading edge so that it could pass through the edge of the embedded lip seals in the ThorPlas-Blue material.

The 994 gross ton, 1993-built tug has been operating with ThorPlas-Blue for over two years now and the owner is confident that the new bearing and seal design has delivered greater operational efficiencies to the vessel’s articulating rudder.

Caption for photo: ThorPlas-Blue bearings installed in an articulating rudder.