A left hand counterclockwise rotation prop is already trying to turn the boat right hence the need for drives offset to the right or shimmed to the left and/or left rudder trim so why not go in the natural direction the boat is already trying to pull. Pretty simple just turn right and don't fight it. It is the correct way for the direction our props spin. I don't think all the engines are going to spin the othe way or props to match anytime soon so best to take right turns. I mean really why do Nascars Ovals all go left? So they can see better. LOL.
I read this somewhere thought it was funny,
It goes back too the cave men. Being that most humanoids are right handed, that was the hand they carried their club in. Leaving their left hand open
Without proper balance, this made the early humanoids tend to always drift left. Eventually this developed into a circular/oval pattern.
Thus the established direction for all racing, footraces, skating, horse racing, power boating, and car races.
So, it's because of human DNA.
Twin rotations are another whole different topic. Same way, inward, outward, clockwise, counterclockwise, twin props on single shaft counterrotating.