Why is there a chain from the top of the rudder to the transom? I have never seen that on a boat before.
The chain is the simplest sort of rudder stop.
After 35 deg or so the rudder becomes a brake , so the chain is to prevent this from happening.
It also helps when in reverse , as again too much rudder is a brake and does not help the handling of the boat.
The rudder looks OK in size and should work just fine.
If extra help is required at extreme low speeds a T style tab can be placed at the trailing edge.
Our launch has a very small rudder , as it has a second backing rudder to assist at low speed.
This is no longer enough as the prop diameter went from 27 to 32 inches which blankets the rudder.
Two pieces of 90deg SS angle bolted to the trailing edge of the rudder , to form a diamond helps a good deal.
Keep the chain on the rudder , it will keep you out of trouble.