Typical shells are what we call displacement forms. They, by their shape, available power or both are limited to a speed governed by their waterline length (LWL) They lack the shape, power or both to overcome the resistance and wave system they generate as they move through the water. Provided enough power they can partly or fully climb over this wave train system and travel at higher speeds. Generally they are not shaped very well for doing this and if were over driven would likely become unstable and capsize. Speeds over the theoretical max hull speed (the square root of the LWL times the speed to length ratio) are met with a dramatic increase in resistance, generated by her shape and the wave train she's dragging along with her. To over come this the craft will need more power and or a different shape.