ORIGINAL: theturbo6guy
that thing is sweet, i personally would reccomend a 1/4 scale or larger servo with metal gears, and find a way to increase the leverage on the push pull idea. sort of like an extended servo horn with a steering stabilizer from a truck, to reduce shock
then again its just my 2 cents...best of luck! please post some vids!
An extended servo arm would reduce the force and increase the stoke, Hydroplanes require small rudder motion at speed but plenty of torque. Water is harder than air!