This item was posted on the HOW site recently:

New Rudder for H27
I tried to order a new rudder from IdaSailor.com and after 3 weeks was told they just decided not to make spade rudders anymore. Foss Foam said to order from newrudder.com but there is no such web site. Any one know of someone who makes replacement spade rudders for 1980 H27 and has any experience with the product?

Phil Herring replied with this url:

http://shop.hunterowners.com/detail-ff.htm?fno=0 and group=889