: My question is, how many degrees should a rudder be able to turn or rotate
: (left/right) before it becomes inefficcient?

: Glen in Baie-St-Paul.

Kinda difficult to answer easily. The rudder will usually be effective with high angles if it's turned gradually. If it's forced over hard all at once it'll likely stall, it is a hydrofoil (airfoil in the water) and will stall just like an airplanes wing at high angles of attack. A foil shaped blade is more resistant to stalling btw than a flat blade like those chopped out of aluminum sheet. No more than 45 degrees right or left btw, any more and it's a brake.

Bill H.