Ida Sailor sells a rudder assembly that requires no boat modification. The cost is $479.00 plus shipping (December 2011)
Ida Sailor products are built well and will last a long time.
Unfortunately there is an issue with the the rudder. The size and shape of the rudder exceeds that allowed by the MCA.
Therefore, the IDA Sailor rudder assembly cannot be used in class sanctioned events.
Bottom line: If you are going to put $500 into a rudder assembly, buy a Nickels. The Nickels rudder meets class standards and you will be supporting our class builder.
Here is a link to the Ida Sailor Mutineer rudder assembly: http://www.idasailor.com/catalog/default.php?cPath=30
IDA Sailor rudder assembly on a Mutineer.