Reply by Loren

You can do it on a big band saw sold for that. You can
also do it by hand with a bow saw.

Your boards will probably distort after resawing and the
advantage of resawing such wide boards is generally
lost due to cupping in my opinion, but you can do it
if you like. If the idea of managing twice as many boards
makes your head hurt I wonder what the price tag on
a machine with a 15” resaw capacity will do to you.