EVALUATION OF HULL VIBRATION REDUCTION USING MULTI-LAYER TRANSOM COVER FOR OUTBOARD MOTOR
The article discusses the results of experiments on measuring vibration of the hull of a small vessel using various methods of vibroinsulation of outboard motors SEA PRO (nominal capacity 5 h.p.) and SEA PRO (nominal capacity 2.5 h.p.). There have been recorded the harmful effects of prolonged exposure to vibration on the human body, as well as on the boat hull and outboard motor. The peak vibration level was measured and the effectiveness of different types of vibroinsulation was evaluated. The experiments were carried out using a vibrometer Ekofizika-110A made in Russia (relative measurement error ± 0.5 dB) and a vibrometer AR63A made in China (relative measurement error ± 5%). The illustrations of the vibrometers used are presented. It was determined that a multi-layer transom cover is a fairly effective way to reduce the vibration of the motor boat hull. The highest efficiency was achieved for the outboard motor SEA PRO 5.0 when it was running at full speed; a 17.3% reduction in vibration was recorded when using the relative value of vibration acceleration (dB). For the outboard motor SEA PRO 2.5 running at medium speed the decreased vibration (9.5%) was recorded when using the relative value of vibration acceleration (dB). The conclusion has been made about the prospects of reducing the vibration of outboard motors and the need for scientific and experimental research, as well as for the development of standards for permissible vibration of the motor boat hull, which can limit the harmful effect on the crew, the boat structure and the outboard motor. The formula of the logarithmic levels of vibration acceleration in relative units is given in accordance with generally accepted sanitary rules and regulations.