I am about to make a form for gluing up my deckbeam.  I understand that the form is supposed to be 15" radius to allow for 1" springback and a final radius of 16".  However, assuming the form is inside the curve (i.e., against the bottom of the beam) and the beam is about 1" thick, shouldn't the radius be 14" to allow for springback to a 15" inside radius (and therefore a 16" outside radius)?  I wouldn't think it would be a huge deal one way or the other, but it does have to match the radius of the bulkhead if the wood is going to be in contact with both.