When a 9,280hp workboat returned to service following extensive repairs at the James Marine Paducah River Service yard in Kentucky, U.S.A., it marked the first application of Thordon’s new seal-embedded bearing to an articulating rudder.
Articulating rudders
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 the higher operating pressures and abrasives, and as a result, require a more robust bearing and seal solution.
For one marine transportation service provider in the United States of America (USA), however, a key requirement was a grease-free bearing capable of increasing the intervals between dry dockings and reducing operational costs.
Thordon’s new bearing seal combo
Thordon engineers recommended a bearing using the company’s proven ThorPlas-Blue material
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 bushings down, reducing the workboat’s in-service time,” said Kasey Cummings, Technical Sales Manager at Thordon Bearings.
Reduce fuel costs
The workboat operator needed this type of rudder to do what it was designed to do – reduce fuel costs – however frequent drydocking for rudder bearing replacement was eating into any fuel savings.
With a fleet of more than 50 line-haul vessels and 800 dry cargo barges, the operator’s fleet transports over 40 million bushels of grain each month, so fuel savings can really add up.
New design optimises operational and cost efficiencies
“The new design certainly optimises the operational and cost efficiencies associated with an articulated rudder,” said Kasey Cummings.
Thordon introduced the design back in 2020 and installed the 3.149in (79.98mm) diametre 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 US inland waterways.
ThorPlas-Blue bearings
Thordon’s robust bearings was also installed to the 168 x 45ft vessel’s rudder flaps, main trunk, and pivot pins
As part of a comprehensive engine and propulsion overhaul, Thordon’s robust bearings was also installed to the 168 x 45ft (48 x 13.7m) vessel’s rudder flaps, main trunk, and pivot pins. In total, 16 ThorPlas-Blue bearings were supplied and fitted.
Kasey 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.”
Convenient and straightforward installation
Kasey Cummings furthered that 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 994gt, 1993-built tug has been operating 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.
Additional orders for ThorPlas-Blue bearings foreseen
Thordon expects to receive additional orders to replace the articulating rudder bearings on other vessels in the fleet with ThorPlas-Blue bearings.
