How to build a boat which is fast?

All I can do is give you some basic guidelines because of the physics involved in moving through water. In general, the smaller the cross-section of the hull, and the longer the hull proportionately, the faster for any given displacement. This is why a catamaran can out run a V-hull of equal displacement. Then, as you narrow the corss-section, you have to consider propeller torque and the effect on the hull. Here, the catamaran twin hull with a screw in each turning in opposite directions gives the best of both, minimal cross-section and counterbalance to the torque from the drive train. Last, look at the bulb nose on huge vessels, like oil tankers. That bulb breaks the water in front of the bow to reduce the force necessary to move through the water, and also lowers the bow wake which means less energy to travel at any given speed. The three things together, narrow cross-section, twin screws and bulb nose all will contribute to more speed.