i personally think that the eyelet is WAY too low. with it that low, when you winch it it's putting the stress right where it broke. with it up closer to the top, it puts the force on the sronger pieces of the boat, and distributes the force down the side rails better. you had a really nice bow piece replaced on the front, and i'd personally mount it as close to that as possible. this way, when you winch it it would be putting the force on the tubular aluminum that's welded up there.
i literally just had this happen on the jet jon i'm building. i float tested it this weekend, and when i was winching up the boat, i heard what sounded like the fiberglass cracking (it's a fiberglass jon boat). i was on a boat ramp with a VERY steep incline, and i was winching it up about a 30 degree angle. luckily, it was the wood reinforcement cracking inside, not the fiberglass. i relocated the u bolt up high on the bow, and it worked much better.