i was thinking of making a stabilizer rudder for  fishing on windier days with my pond prowler. the  boat is  10 ft long . anybody have any idea of what dimensions it should be, Ive never seen one before to go off of.

I took a bracket off of an old hand controlled, stern mount trolling motor, got a 1" steel pipe and welded an 8" X 14" piece of thin steel to it.  You can raise and lower it and adjust the height.   

Exactly what Ring fry said.

It makes a world of difference.