I have used Contact Cement on several boats below the water. They were double planked boats and the top plank was held in place with Contact Cement. I applied cement to the base plank and the top plank, let dry for 30 seconds and then put the top plank in place. Place it carefully because you won't be able to move the plank. Remove any excess cement. The hull was then covered with 2 oz fiberglass material and finished with polyurethane, sanded and polished.