Agree with Roger--the plate on the outside of the hull may or may not be attached to the U Bolt. It is not a bad idea to put several more layers of glass on the inside of the hull, to thicken the stem at that point. I would pull the U bolt, clean it well with acetone, and clean the hull under the plate with acetone. Then put some 4000 3 M sealant under the plate on the outside, and put the backing plate on the inside back on, and tight up the bolts until fully tight.
I agree, with strap down, but use use a chain to the trailer frame.