G'day again here's a shortcut that was given to me when I asked about tuning the 5.8 in a thread on this forum called
"sail tuning on 5.8"
This is for your cat
http://groups.google.com/group/austincats/web/nacra58-tuning.pdf
This is for Goose's tuning guide also really well explained but I don't know what bits are wrong for your cat
http://goosemarine.com.au/Articles%20|%20Photos
There is an expanded version of this guide with photo's on "catsailor.net" in the Nacra users forum called Nacra 5.8 Tuning Guide
http://www.catsailor.net/cgi-bin/ubb/Forum5/HTML/000495.html
Do you have an outhaul on your main sail or holes?
Take heaps of photo's and give us a look. I've posted a video of me sailing and photo's for comment and got great advice on boat setup and sailing technique
regards