Hi, follow the following link and it will take you to the American Model Yachting Association
http://www.modelyacht.org/
As soon as you get into the site, on your left you will see a menu, click on 'Boats', then on 'Class Page', scroll down and click on US 1 Metre. When you get to the US One Metre page click on 'construction tips, file and plans. You will see a (4) four part section on how to build a model from balsa. even though the section is to build a US One Metre it is like the bible that most modelers follow to build any boat. As you may know is that the US One Metre is very similar to the IOM.
GOOD LUCK
If you have any other questions feel free to ask me, I have been building these models for about 15 years.
Steve