depends how good a "fix" you want. Doing It Right and More-or-Less Forever means: pulling floor, testing for leakage by filling bilge with water while boat is on trlr and marking leaky rivets, rebucking or replacing any leaky ones, taking hull down to bare metal inside, covering with some goop called "Gluvit", then replacing floor. West Marine sells some stuff that's applied to outside of hull but you stll have to do the leak test and take hull exterior down to bare metal, and you probably have to flip boat (a little easier with 14' than 21' cruiser...). look at some of the resto threads for pix of process. and imagine doing this job on a 21'..........
i'd start with just doing the leak test with floor installed and see how bad it is. if not too bad and floor is otherwise OK, and you won't be more than a mile or 2 from shore, i'd just get a second 1200+gph (AKA 2gal/min) bilge pump and check its operation before every trip (the Slob Solution)
