What do you all think about this? Anyone experienced with recurring hull cracking?

The last two years (the length of time we've owned the 2000 moomba mobius V - we bought it used) we have been having issues with cracking near the lowest point at the bottom of the boat - right below where the ski locker ends and the fuel tank begins. (We believe the previous owner sold us the boat in this condition without disclosing the problem as it looked like it had been patched the first time we tried to have the crack fixed) The crack is a V shape that spread up the boat but is less than a few inches long on each side.

We had a fiberglass person patch it twice now which involves removing the fuel tank and patching it inside and outside, and both times over the summer the crack has started to appear again. The second time we had it patched the inside patch held, but it still started to crack again. He is recommending he re-fiberglass the length of the boat on the bottom figuring that there is just too much flexing going on between the hull layers and a smaller sized patch isn't enough. It is going to be a rather large sum of money, and I'm only willing to commit if it will solve our problem permanently.

Below are 3 images, one that just shows our boat looking all nice, and the other 2 pics are of each side of the bottom of the boat showing the crack as it creeps up the hull. Again, the location is right below where the ski locker ends and the fuel tank begins.