multiman i dont know who you are nor do a care yet you still try to pour scorn on me when i was trying to help out a mate.Did you say you used to make comercialy available boats? i wonder why you still dont?.theres a word for guys like you but its not allowed on these forums so this one will need to do POMPOUS!!.good luck with it andy sorry you failed with your grp floats ,but maybe THE EXPERT will help you out on how to do it? i doubt it though but you never know.By the way multi i think i realise who you are and i doubt very much your english .seems to me your just here to cause trouble to me.by the way andy the foil on the rudder needs to be the shape of an airplane wing but upside down that will give you the shape you need .