There are cracks and then there are cracks
I was scared to death when I first bought my Mac 25. I was down in the V berth looking under the berth through the access cover when I saw light coming through the hull. Checking the outside i found a small nick in the gel coat. An expert at a local marina informed me that this was not uncommon. A crack or scrape in the gel coat will let light through and look like a through and through opening when in fact it is only a crack in the gel coat. Flood the area with water and check below for any water seeping in. No water, no crack. Unless someone has over stressed the cockpit seats and floor, you shouldn't need to reinforce the fiberglass. If you put a peice of black electrical tape on the crack and can no longer see it from the inside and the water soak through test is negative, you just might need to repair the gel coat only.Don't jump to conclusions because you see light on the inside. Check carefully, the repair might be simple.Happy SailingMike