I have recently acquired an old 12ft aluminum Springbok that I want the kids to be able to use. When I got it, there was a big glob of putty in the area surrounded by white in the photo below (the top of the photo is the front of the boat - this area is where the bow begins to curve up). It leaked, but not too bad. The putty has come out and it leaks quite a bit now. I don't understand why this area is cut open anyway... is this how it was designed or did someone cut out this groove for some reason? Anyway, my main question is what should I use to plug this area back up?