What is the relationship between number of propellor blades to the horse power of the ships engine?

What is the relationship between number of propellor blades to the horse power of the ships engine?
Without delving into fluid dynamics or excessive physics, a simple explanation:The relationship lies in the specifics of an individual ship. Most ships run diesel engines, which provide large amounts of torque at low rpm (more fuel economical). Though any sized prop will move a ship, more blades will produce a higher thrust, which is more efficient when using an engine with high torque.For commercial purposes gasoline engines are sometimes used to allow higher rpm. In this situation a prop with high thrust (more blades) will be less efficient, as the engine would not produce enough torque to redline (top speed).Note: Diesel fuel will not produce enough vapour below about 122F or 50C to ignite, however gasoline will and is commonly regarded as being more dangerous for use on board vessels.