If the original poster has an H336, then he doesn't have any stainless steel in his rudder. Those boats were built with Foss Foam rudders and have a composite rudder post. There is no issue with corrosion to worry about, even if the rudder if full of water. It could still freeze and crack the blade though. To be sure, remove the deck plate aft of your pedestal and take a look at the rudder stock where the radial drive wheel is mounted to the stock. My guess is you'll see a thick walled hollow tube for a rudder stock, and not a stainless steel shaft.
The all composite rudders are a pretty cool design, because of the fact that there's nothing to corrode. They're also much stronger than a conventional fiberglass over steel shaft and webs type rudder. The only complaint I've heard about them is that they don't give you any indication if you damage them severely and weaken them. If you go hard aground with a conventional rudder, the fact that your rudder is now sticking out at a funny angle tells you that you hurt something. With the composite rudder stock, if you ran it hard into something, you could crack and splinter the shaft, but you wouldn't be able to tell untill it just fails and falls off.
