The rudder problem is due to the shape of the rudder that hobie makes so what type of rudder is it? Sand down the whole rudder a little it will make you go a little bit fast and you would notice the hum will dim abit. The edge of my rudder is thin as and i cant get a hum easyly the only time i could get the hum is when i pushed my boat as hard as i could in 42 knotes of wind with the boat flatish. Well It comes down to experiments. have fun