Don't buy a Dotan rudder, the service is non existant if there is a problem.
I paid good money for a rudder and received a damaged blade, then they came up with all sorts of reasons why it was not their fault.
Leonid at Dotan will not answer my emails.
There is also a design fault with the rudder for the Optimist and it will damage the boat if the boat is not modified.
I will attach some pics asap.