Bob,
The bunks will get the natural bow without having to do a thing. Just make 
sure you measure twice, cut and drill once. Be sure to replace all carriage 
bolts with new and if you staple the bunk carpet on, put the stainless steel 
staples on the bottom side of the bunks. I found it easier to do one side at a 
time, leaving one side intact for reference as needed.

Rummy