Thus, the engine may be overloaded. In either situation it is likely that the engine is not operating in its optimum fuel efficiency range. Also look for propellers that have been repitched , i.e., blades are mechanically twisted or hammered to a different pitch. Another potential source of vibration. Blades Blades are the number of blades the propeller has.
Most propellers are two, three, four, or five, bladed.
The most common are the three and four bladed propellers. Two bladed propellers are primarily used on sailboats. The fatter the blade the more blade there is to push the water. Others prefer the lower cost of the three bladed propellers. In general, the four bladed propellers may be a smaller diameter that the three bladed propeller.