FLZ is a generic state assigned HIN number from Florida, before 1972/3 or homemade. Looks 1970's sportcraft'ish to me . . . just a wild guess. Seacraft only made one model production 15ft'r and that's not it.
http://marinesurvey.com/yacht/stolenboat.htm
Many states have a provision in their titling law that allows for the reassignment of a hull and registration number. This is called the "homemade boat" provision which provides the opportunity for a great deal of mischief. Let's say, for example, that I acquired a 1976, 29' Seabird hull and completely rebuilt it with new deck, interior and engines, etc. I could apply for a new title under the homemade boat provision and be assigned an entirely new hull number and title. In Florida, the new number assigned would have an FLZ prefix that indicates a homemade boat. The problem here is that stolen boat artists can do the same thing with any stolen boat. Therefore, any boat with an FLZ prefix should be viewed with great caution.