Welcome to the 3170 slide crack club. I have a 2014 and a crack. As I was just out of warranty, I took a wait and see approach. LOL, my crack has run down to the seam but has not opened up any larger. LMAO. Four years on the crack, so far, so good. I check it often. I would recommend getting it repaired if under warranty and /or drilling a small hole at the bottom of the, uhh umm, crack to maybe stop the run until repaired.
Search this forum. It has been discussed.
2014 Sunseeker 3170 DSF
Dorothy, Garrette and Miss Bella.
Retired and having fun.