Henri got a 25ft. It seems 25ft is a great good boat to learn, have fun and sleep some nights in. In Brazil costs likd 30k BRL but 5-10k USD in US/Canada.
Famous boat designer: https://www.wharram.com/site/self-build-boats
Kits for DIY sail boats: http://www.clcboats.com/shop/wooden-sailboat-kits/
Gustavo Brum: http://projetosdeveleiros.com.br/wp-content/uploads/2010/08/Plano-de-Estudo-PP135.pdf
Nice one from Roberto: http://www.yachtdesign.com.br/portugues/projetos/mc34/desc34-1.php http://www.yachtdesign.com.br/portugues/projetos/ex39/expl39_1.php
https://sourceforge.net/projects/freeship/
Brief how to on boat design: http://www.duckworksmagazine.com/04/s/designs/morten/designing/Part1.htm
http://joecoopersailing.com/building-a-mini-transat-6-50/