Metalastik Anti-Vibration Mounts for Alaskan Ferry

Metalastik's Cushymount K anti-vibration mounts have been chosen to isolate exceptionally heavy machinery in a new RoRo ferry, M/V Kennicott, which recently went into service in Alaska. Cushymount K units are rubber/metal assemblies incorporating four spring elements housed between top and bottom casings of S.G. iron, and were found to be the only mounts capable of meeting all aspects of the exacting specification for this application. All crew and passenger cabins on Kennicott have noise levels of 60 dB(A) or less, and dining areas and lounges have a noise limit of 65 dB(A). Shipbuilders Halter Marine were advised by specialist consultants Noise Control Engineering on a series of measures to minimize noise and vibration, including the isolation of exhaust silencing equipment. The exhaust silencers used in M/V Kennicott are exceptionally heavy, as they include an environmentally friendly waste heat boiler to re-use excess heat from the exhaust system. In total, they weigh 35,000 lbs., spread over four mounting points. The specification produced by Noise Control Engineering required each mount to support a load of 8,750 lbs., and called for an elastomeric, rather than a steel spring element to achieve the optimum vibration reduction necessary for noise control. In addition, the elastomeric element had to be encased, to protect it from the harsh shipboard environment and to incorporate limit stops to protect the silencer during excessive ship rolls. Finally, the specification called for a fail-safe design to prevent the machinery from coming loose, in the unlikely event the elastomeric element broke. M/V Kennicott went into service on May 1, 1998. Owned by the Alaska Marine Highway System, the ship measures 380 ft. in length, and, depending upon routes, will carry between 500 and 750 passengers and 120 vehicles. Noise Control Engineering Inc., is based in Massachusetts, and specializes in the design, testing and monitoring of noise control solutions for marine, industrial, architectural, environmental and transport applications. Metalastik Limited is a member of the BTR Group. The company specializes in the design and manufacture of rubber to metal bonded components for anti-vibration applications and suspension systems used in the automotive, rail, marine, offshore and other engineering industries.