Stem - 2

Slowly proceeding with the stem. All the laminating is done so last nite I began "rough" cutting it to shape. So, while it was clear and obvious how to work on the outer arc (see picture) - sawing, planing, sanding, whatever, I got stuck however on the inner arc - no idea how to properly work it with power tools (I do not have an access to a beltsaw). Looks like it will take hand tools only.