Rudder idea

So I have heard all about how some rudders have more flex in them than others so lets fix it.

What if you drilled a hole down the vertical axis of the rudder and slid in a reenforcing rod? (steel, aluminum, wood)
Just food for thought.

the everpresent question, Is it class legal?

I think there are no problems with the Hobie Class rules and regulations. The blade does not need to be original equipment - nor does it need to be made from the original material (this is why EPO's are class legal).
I do not see what device would drill that hole... ... tapered, two feet deep, not much tolerance towards the outside of the blade.
... The blade is so skinny that whatever ("wood, steel, aluminum") you would insert in that hole would not contribute much to the blades stiffness.
Not sure if a carbon fiber rod as some sort of stringer would help.
The thermo plastic / lexan blades are not particularly good blades. I would not mess with them.
Buy a composite blade - original Hobie equipment or EPO - they are both good. Or try to make your own - laminate over a foam core with the composite material of your choice - vacuum bag if you can. Look for Jamie's attempt - I think he just finished his second blade.