Welcome PM Browser, we are sure you will have many enjoyable days on your TI.
Have a look at the rudder in the fully down position, out of the water if you can.
You will see that a small forward section of the rudder is forward of the pivot line.
When in the water, this section actually pushes the rudder and acts like power steeering.
If you look closely at aircraft control surfaces, you will see the same section.
The end result should be comfortable control on the small tiller handle.
We can sail all day without discomfort, when it is working right.
There could be other problems but check this one first.
I notice a thump coming through the hull when my rudder is fully down.
Of course if it is fully down and no other obvious problem, go back to your dealer.
And most of all, enjoy.
Cheers, Brian in South Australia