Here is a link to a video on how I made a R/C paddlewheel riverboat from display foamboard. Enjoy and I look forward to your comments and questions.
Please feel free to share this link with your friends and fellow hobbiests.
https://www.youtube.com/watch?v=BeSk2N9uIIU&t=615s

Welcome to the forum I enjoyed the video.   

Very nice and very ambitious. Looks great!

I too like to use foam board but I haven't yet for a boat. It has worked well for me in model theatre's and dolls houses. I think I might give it a go on my next boat project...thanks for the idea!

Great. Waiting for the on-the-water video.

I have used foamboard a lot for planes, but not yet for boats. You just gave me an idea how to build a barge for my Morangie Castle paddler.

Jurgen