There are a lot of different types of boats on Bangkok's Chao Phraya River. When you are in a hurry to get somewhere a trip in one of these can be very quick indeed. They are powered by a variety of engine types both diesel and gasoline with some equipped with turbo chargers. The engines are not fixed to the boat. The engine pivots as well as tilts up and down. Steering is accomplished by moving the entire engine via the tiller. Water depth is accommodated by tilting the engine. They spin a prop about 12" in diameter.