There are a number of different motor boat types commonly seen and in use today. They are categorised primarily on how they move forward. Displacement craft, the vast majority of large ships and work boats, travel through rather than over the water. The hull type of this type of craft is slower than planning boats but they have the advantage of having better sea going properties such as stability which is vital for the job they are designed to do. Semi displacement craft have finer bows than displacement craft which means an easier entry when going forward into an oncoming sea. As a result the hull partially rises out of the sea as speed rises. Planning craft are the fastest of the motor boat types. They often have powerful motors that are needed to drive the boat forward to such a speed that the boat begins to plane on the water. Speed and manoeuvrability are the benefits but these tend not to be good sea going boats in rougher weather.