Is it possible to build a good motor boat from the foot material, with a not expensive four-stroke engine at a cost of 6000-8000 rubles? Which, at this power, will develop a speed of 15-18 km h? I have on this account, there is an idea sketch: the project of a long-lasting, inexpensive, displacement, motor boat " Yarty "which means" half " in Tatar. The very idea of "nationality" lies in the body with a built-in shaft, protected, propeller and rudder tiller. A scheme that allows the owner to install inexpensive, various, removable engines, whether it is a gasoline or electric motor with a simple transmission pulley-belt. A trimaran with a large ratio of L/B> 7 and due to the low resistance of the hull, a higher speed will be achieved than that of conventional displacement hulls with an average power of 5 kW. The pressure of a liquid (or gas) is greater where the velocity of its flow is less and Vice versa, the Bernoulli equation. Material: HDPE, ABC plastic, recycled plastic waste. Powder-coated steel. Performance characteristics length-4500mm width-1700mm Board 800mm weight 80 kg. The engine is any four-stroke motor unit up to 5 kW or an electric motor with a battery up to 2 kW.