Re: How would you fix this?
Triple agreed, attempting to cosmetically fix that will do nothing. The crack will re-appear the first time you hit a wave or small wake...or possibly just on the trip to the water. It'll need proper repair. If you don't care about appearance you could try some silicone (GE 4200 or 5200) it'll flex a bit and seal it up to prevent water comming in, but I don't recommend it.
ian