Matt How many types of rudders are there? Advantages?
In general, you want the rudders to be as light and stiff as possible. The profile is fixed by the class rules, as is the thickness.
The original 14 / 16 came with rudders of white PVC plastic. They have a nasty habit of getting brittle over time and snapping off right below the rudder casting. They're also not very UV resistant. They turn yellow in the sun.
There were a lot of aftermarket rudders being made out of fiberglass (heavy) and wood (pretty, but not very durable).
In the late 70's, Lexan rudders were introduced. Still heavy, totally unbreakable, but man did they flex! It was almost impossible to get a smooth surface finish on them. They were pretty much impervious to sanding.
Then in 1984 came the EPO Rudder
(said with reverence). Foam core epoxy fiberglass. So light (about 4 lbs) that they changed the class rules to make them legal. Super stiff, super foil shape, hard superlative finish. Their only flaw was that they hummed miserably until you (very carefully) worked out the bulb on the trailing edge.
Unfortunately, they were only made for about 5 years. In 1989, Coleman sold Hobie Cat and away went the proprietary process that made the rudders. Until recently, nothing ever came close.
Since 1989, you could get the racer rudders (foam core fiberglass) - heavier than the EPO's, but nearly as stiff although the gel coat finish was a little soft compared to the EPO - or you could get the "plastic" rudders which I believe were made of polyester.
In the past year, though, Hobie Europe has brought out carbon fiber epoxy rudders that are very light (about 4.5 lbs) and very stiff. I just got a set for my 16, and I must say, they are very pretty.
But just last night, I got this photo in my e-mail:
Hobie Cat is re-introducing the EPO rudder! Same foil shape - but digitally faired. The top one is carbon / epoxy; the middle one is carbon / Kevlar / epoxy and the bottom one is polyester.