The flange and locker were put in place to check the fit.

The fit was pretty tight between the locker and the flange -  tighter than I would have liked, but it will have to do.  The flange was intended to ‘float’ up or down from the locker box during the installation.  I considered making the flange a part of the locker box, but the measuring precision would have been all the more complicated.

After some surface prep, the box and flange are ready to be installed into the boat.