Energy Management Case Studies

Noise Control POLYFORM® Molded Outboard Motor Application

Description of the Request:

In conjunction with the client's engineers, tests were run that determined the newly designed two-cycle motor was operating at sound levels 11 to 12 decibels higher than the four-cycle competitor's motors. It was requested that Polymer Technologies, Inc. (PTI) design and develop acoustical barriers for the OEM client's two-cycle outboard motor, such that it would be acoustically comparable to competition's four-cycle outboard motor of equal horsepower.

Noise Control Solution:

After extensive testing, PTI determined that the majority of noise was being emitted from the lower exhaust section which is just above the waterline and the sound source was the motor itself under the upper motor housing.

A feasible and effective solution to the lower motor noise problem was an encapsulation of the lower unit of the outboard motor. By designing and acoustically testing a variety of POLYFORM® molded urethane foam parts of varying densities, a much greater containment and absorption of the sound energy was achieved. The final design completely surrounded the lower unit well below the water line, necessitating the use of the Polyshield® version of POLYFORM® which has an integral surface skin.

The upper motor cover was lined with one very large molded piece of the Polyflex® version of POLYFORM® because the sound testing showed a predominance of high frequency energy, and there was not the need for a thick skin to prevent water absorption as was the case in the lower unit which is partially submerged in water.

The end result was the creation of acoustical barriers that met the desired noise control and reduction in sound energy of the two-cycle outboard motor. This resulting sound reduction was at levels equal to and, in some RPM ranges, below that of the industry leading four-cycle competitor.

(Specifications subject to change without notice. Check with factory for latest revisions.) The Federal Trade Commission considers no existing test methods or standards regarding flammability as accurate indicators of the performance of cellular plastic materials under actual fire conditions. Results of existing test methods, such as UL-94, MVSS-302, SAE J-369, and FAR 25.853 are intended only as measurements of the performance of such materials under specific controlled test conditions. Any flammability ratings shown are not intended to reflect hazards presented by these materials under actual fire conditions.

The information contained herein is based on laboratory test data developed for PTI and is believed to be reliable, but its accuracy or completeness is not guaranteed. The buyer must test any product to determine the suitability for h is specific application before use. PTI DISCLAIMS ANY RESPONSIBILITY FOR: 1) WARRANTIES OF FITNESS AND PURPOSE, 2) VERBAL RECOMMENDATIONS, 3) CONSEQUENTIAL DAMAGES FROM USE AND 4) VIOLATION OF ANY PATENTS OF TRADEMARKS HELD BY OTHERS.

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