Yes, Hullform 9 doesn't seem to like that one...
Just saved a version using Hullform 9. I suppose I ought to cut the flares off and draw racks on it, but I'll leave that as an exercise for the advanced student...
Could Phil or someone please replace the one on the Cherub site with this one if it works OK for Jack please.
http://www.devboats.co.uk/jimb97.hud