I don't understand the difference between a 1.5" diameter ring and a ubolt that has a threat-to-threat span of 1.5". Once the threads the ubolt or the bottom of the ring are embedded into the boat all you can see is a small part of the curve. Could you even tell what the embedded portion looked like?

Can you tell if I used a loop or a 'U'? I decided to extend the loop a little proud, but I could have buried it more, almost to the point of uselessness.

After attaching the u-bolt plate and bolts, I know that this boat could get hit dead on by a tank and that u-bolt will still be anchored into wood and epoxy.