I am Pierre, the creator of Voile-RC, a community site for radio controlled sailing enthusiasts. Although the site is not an "advertising" site, we have always made room for quality craftsmen (as Dominique aka "CNI"). And it is true that the french "Step By Step" written by Dominique is awesome.
We started the English version of Voile-RC few weeks ago: http://en.voile-rc.com
Dominique has created on it a group for Youpis owners - or future owners;-). He have done a first and quick translation of the construction guide in English and shared it on the Voile-RC english version.
So, if you are interested in, we would be happy to welcome you to share your experiences (and photos, videos, events,...) around Youpi ...
PS: I did not say it before but, obviously, Voile-RC is a free website :-)