Router cutter


Curious about Wooden Canoes
I am looking in the canoe craft book. I cannot find any details about the radius of the cutter used for the edge of strips. If the boards are 6mm thick then the cutter needs to be bigger or the edges will be too thin.
Any ideas.

Thank you in advance
A 1/4" thick strip with a half round edge has to have a 1/8" radius. Some are going to the 3/16" bit to get a less sharp corner on the cove. Personal choice...