A quieter cruise

Heavy marine engines are not only powerful, but also extremely loud, issuing vibrations which spread through the entire hull. Researchers at the

(LBF) in

have found a way of blocking the sound immediately below the engine with the help of counter-vibrations.

Marine engines are attached to the ship’s hull via bearings, either directly or on an engine mount, meaning their vibrations can easily spread through the entire hull of the ship. The only way to dampen these vibrations is by absorbing them directly at the bearing.

The solution devised by the researchers is to install an active damper between the engine and the bearing. This active bearing is made primarily from piezo-ceramics, materials that can change their shape when electrically stimulated.

If they are stimulated very quickly, they generate high-frequency vibrations – which are exactly what marine engines need. Using sophisticated sensors, the scientists measure the engine’s vibrations and trigger the piezo-ceramics such that they precisely counteract this motion. Because the active bearings carry the weight of the engine directly, they are able to perform to maximum effect.