Rudder size calculation

Hi
I'm trying to find an easy way (or should I say...easiest) to calculate the size of a rudder, best dimensions of height & length, balance & how far back is the absolute limit a rudder can be positioned without cav plaes.

This is all for a single engine planing hull of about 30foot & max speed of about 35 knots.

My main purpose for this question is obviously to have the correct rudder. But the second very important reason is to push the prop as far back as possible without comprimising my steering ability and to decrease shaft angle..

Cheers

 

Geez. I must be in the wrong forum section.

I worked out about 1 square meter of rudder area in total of both sides. I took the calcs down to a Sydney Rudder designer/builder. He said it was a pretty good size & on the "larger than normal" side. It could be a little smaller if I want. Span is about 65cms & chord at max width is 40.. which he said could go down to 35 but not necessary.

What are people's opinions on this from their experience?

Come on people. At least answer one of my threads. A little help would be nice.

Cheers