Only reuse your current boards if they are pressure treated. Forget pulling the staples. Either cut the carpet off or apply new carpet over the old carpet. If your current boards are not pressure treated, toss them and buy new boards. Buy marine grade carpet to minimize mold, mildew and rotting. Use stainless steel stapes. Galvanized staples will not stand up against chemicals now used to pressure treat lumber.
We offer 20 oz marine grade carpet already slit into 14"W x 100'L rolls. Contact Jerry at firstname.lastname@example.org