Read you bought your Hobie 16 three years ago and do some 4 races each year. Based on the white hull color I assume you are the first owner. Why did you check in the first place as the crack can hardly be seen? Did you have too much play / less stiffness between the hulls?
My H16 [#99173] is built 1992 / bought it some 5 years ago and I use it quite frequently. Seeing your pics I got a bit worried and tend to have a closer look myself as well
Eddie