Hill and Cameron. See here prior posts here;

www.seabreeze.com.au/forums/Sailing/General/Red-Eagle?page=1

trailersailerplace.com.au/phpBB3/viewtopic.php?t=16374

The first link above indicates the Red Eagle came before the Red Witch and was "substantially slower". Specs of the Red Witch are here;

sailboatdata.com/builder/hill-cameron-yachts-australia/

sailboatdata.com/sailboat/red-witch-19/

www.johncrawfordmarine.com.au/red-witch

There is a Red Eagle for sale on this site but the australialisted site seems to be clogged with old adverts - it could be still for sale though?

picton-wa.australialisted.com/6229/boats-yachts-parts/20-foot-trailersailer-red-eagle-boatsailstrailergpsmotor_17560231.html

May I politely ask what do you need the plans for? If you are going to build something there are numerous more up to date yachts which would be better to build and would have heaps more value at the end of the build process.

The Status 580 could be of interest as a similar trailerable fixed keeler - would sail heaps better.

rlyachts.net/indexStatus.asp