Hull Optimization Improves Vessel Performance

Several months ago, Avalon Freight Services (AFS) approached Elliott Bay Design Group (EBDG) to explore different keel options to improve the directional stability of its landing craft, Catalina Provider.

EBDG’s team of engineers 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-foot 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-inch-deep by 30-foot-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. Providing year-round freight transportation from the Port of Los Angeles to Catalina Island, the vessel makes the 21 nautical mile voyage each business day.

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,” reports Tim Bombard of Avalon Freight Services, “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,” states project manager, John Petersen.

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