Why does my boat become unstable at high speed?
The faster a V-bottomed boat travels, the higher out of the water it planes. When the wetted beam becomes too narrow, depending on weight, center of gravity, bottom and propeller, etc, the boat will start to heel back and forth to port and starboard, unless you are a skilled driver and can counteract these motions. The traditional approach to counteract this instability is to place large spray rails at the side of the wetted area to act as support wheels. This might slightly improve stability, but it will make the boat much harder in waves.