Ecology and Environmental Protection https://doi.org/10.5593/sgem2019/5.2 695 STUDY OF THE VIBRATION TRANSMITTED TO THE CREW BY THE EQUIPMENT OF A RIVERBOAT BEFORE REPAIRS PhD student Laurentiu Picu 1 Prof. Dr. Eugen Rusu 1 Prof. Dr. Mihaela Picu 1 1 Dunarea de Jos University of Galati, Galati, Romania ABSTRACT This paper examines the level of vibrations transmitted to the crew on a river ship. This ship made a test cruise on the Danube, between Braila and Galati, round-trip (32Km). This cruise was done before the ship was repaired, to compare the levels of vibrations before and after the repairs and to check their efficiency. There were determined both the vibrations produced by the ship's equipment (engine, generator) and those to which crew members are subjected in the areas where they spend most of their time. To determine the level of vibrations transmitted to the crew, several sets of determinations were made on two sailors, on the main deck and in the recreation room. Triaxial accelerometers were used to measure the accelerations in all three directions. The measurements showed that level on the Oz axis is 7.8% higher than those on Ox and Oy. Also, the acceleration averages in the recreation room are lower by 8.7% compared to those obtained on the main deck. The measured vibration values were compared to the limits imposed by EU Vibration Directive (2002/44). Exceeding the daily exposure limit for whole body vibrations by 97.78% confirms the need for reparations to reduce the level of vibrations transmitted to the crew. Keywords: river ship, crew, vibrations, acceleration, daily exposure limit INTRODUCTION The rectilinear vibrations (vertical, longitudinal and transverse) are transmitted to the human body by an orthogonal coordinate system, originating from the heart (Fig. 1). In this way, the 3 accelerations a x , a y and a z , are considered according to ISO 2631- 1/1997 [1]. Of these 3 directions, the vertical one is the most important for operators (z-direction). Vibrations on this direction are the most damaging to the health of workers, drivers, etc. [2]. The vibrations on the other two directions (longitudinal and transverse) do not cause too much discomfort. However, there are situations (when driving on too rough roads, or during various specific operations) where even these vibrations are harmful [3]. Vibrations induced by rough roads have a frequency below 50Hz. In his paper "Human Body Vibration Exposure and its Measurement," in 1982, Rasmussen made an equivalent, simplified mechanical system of the human body with the specific frequencies of different organs (shown in Fig. 2) [4]. These organs, having different resonant frequencies, do not vibrate like a single mass, which can lead to amplification or attenuation of the entering vibrations in certain parts of the body.