cnc files

Hello, I am in the process of making an 18' aluminum mod-v boat. It seems like a silly question but how would I get the exact curvature on to a sheet of aluminum to cut out without a CNC machine? Referencing the pictures below how would you all draw curves on a sheet of plywood or aluminum?

My brother designed this Boat using ideas from the many boats being used around. He wanted it to look great and easy to handle. Aluminium open dinghy with cross seats. Suitable rowing or with outboatd to 15 hp steering from back. Tough 2mm plate hull is easily constructed from plans. A very...