Engine induced sound and vibration levels in boats for professional and leisure use is in many cases unacceptably high in term of comfort and the environment. Classical methods for passive treatment are normally less effective due to the low frequency content and often leads to an increase in weight. This contradicts the requirements for lower weight for increased speed. More efficient vibration damping methods must therefore be found. With active engine mounts, it is possible to achieve a decrease in the vibrations even when the hull is not very stiff. This is especially important in marine applications since the engines are mounted on weak and light structures. The AVIIS project aims at investigating the effects of a combined passive/active engine mount for use in boats. A Storebro 36 Royal Cruiser with two Volvo Penta engines has been used in the project. An ASAC (Active Structure Acoustic Control) approach has been used. The sound level in the cabin will be minimized by controlling the vibrations in the hull, in this way the active engine mounts only isolates the vibrations that couples good to the sound radiated. This paper will present the key results from the tests with the combined passive/active engine mounts on board the boat.