Elliott Bay Design Group improves directional stability of landing craft

Elliott Bay Design Group (EBDG) has completed a hull optimization project for Avalon Freight Services (AFS). Several months ago, AFS approached EBDG’s team of engineers to explore different keel options to improve the directional stability of its landing craft, Catalina Provider.

AFS provides year-round, scheduled or chartered freight transportation from the Port of Los Angeles to Catalina Island.

EBDG worked closely with AFS leadership to understand the vessel’s particulars, operation and route, detailed project objectives and determine a project plan. Multiple keel designs were considered as viable options for the 150′ landing craft. EBDG then conducted a computational fluid dynamics (CFD) analysis to estimate the effects each keel arrangement would have on directional stability and overall vessel performance.

The analysis also considered the impact the keels would have on the vessel’s low-speed maneuverability. After the analysis was concluded and the results studied, EBDG recommended moving forward with 18″ deep by 30′ long keels located on the vessel’s chine.

EBDG developed a fabrication and installation drawing to guide the selected shipyard, Al Larson Boat Shop, with the keel additions. The Catalina Provider is now back in service, experiencing exceptional results with the hull modification, EBDG officials said.

As reported by the captain of the Catalina Provider and management at AFS, overall vessel performance has improved with the addition of the new keels. Specifically, while transiting to Catalina, the vessel’s tracking has significantly improved, resulting in considerably less required rudder angle. This

reduction is creating less vibration and stress on the rudder bearings, thereby extending their life. The vessel has also gained a half knot of speed with an expected improvement in fuel economy and preferred low-speed maneuverability characteristics.

“Actual results are very similar to test results,” Tim Bombard of Avalon Freight Services, said in a statement announcing the modification. “We anticipate improved performance and an extension of life on all related rudder components.”

“It is rewarding to see the application of our engineering effort pay off for our client with such positive results,” said project manager John Petersen.

 

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