These directions are for gluing foam parts to the interior of a royalex canoe.

 

The recommended glue is Weldwood Contact Cement. Available at most hardware stores, and discount stores such as Wal-Mart.
Whether your gluing kneepads, saddle or ankle blocks, first position and outline the item with a pencil. 
Sand the area thoroughly with 100 grit sandpaper. then clean the area with acetone or rubbing alcohol to remove any dirt, grease's or oil from the surface to be glued.
Apply one thin coat of glue to the foam parts, Then put one coat of glue on the boat surface. The first coat of glue you put on the foam will soak in, so when the first coat is dry, apply a second coat. The hull is non-porous so a second coat is not needed.
When the second coat on the foam and the one coat on the boat are dry, you can contact the foam to the canoe. It is very important to apply it even and straight the first time. The easiest way to do this is to start at one corner and lay it down one side, then around the corner and down that side. Once your satisfied with the alignment, press it down. Use as much pressure as you can and come back 1 hour later to repress if necessary. Try to keep freshly glued boat out of the hot sun for at least 24 hrs. This will lessen the chance of the foam lifting due to the extra heating.