Rudder material for self steering

[Typee]

I am building a self steerer for a 38 foot full keel cutter. This unit will be along the lines of a Hydrovane except it will utilize a trim tab. The Hydrovane would be my first choice if I were to buy a self steerer, but the cost of $5,500 U.S. is hard to justify. I read somewhere that the Hydrovane rudder is made of nylon. I am considering using marine grade HDPE (high density polyethylene) instead. I would appreciate any comments or recommendations.

 

[penultimate]

Because the hydrovane rudder is balanced it is not subjected to high stresses in normal use. I have the supplied rudder in some sort of plastic but I also use a laminated mahogany lifting rudder made by a previous owner. Both are equally effective.