I wouldn't be too concerned given where those are located. Gelcoat is mostly cosmetic, and not structural, so cracks in the gel don't always mean there's a problem. When gelcoat is actually applied during the build process, if it's applied too thick in certain areas (and areas with curves and concaves are easy to apply thick) it will become more brittle than in areas that it's applied at the correct thickness. Being on the chines like that boat is probably just means the guy applying the gelcoat put too much on there. Thicker gel coat is more brittle than thin gel coat, so during the rough days on the lake is probably what caused those stress cracks. Unless the fiberglass laminate underneath it is cracked, I wouldn't be too concerned.
-Mike
2006 Supra Sunsport 20V