Yup, that's how it looks to me. What bugs me is that there doesn't seem to
be much of a backing plate other than the little strip that usually comes
with a standard U-bolt. That said, there's very little room to fit anything
bigger - no extra width, but maybe some more length. Whether any more
backing is needed is something I don't know - I'm not sure on what sort of
strain the rig is likely to put on the edge of the deck, or how well the GRP
will cope with it.


Well, here are two points. One: The rig stayed up thus far. Two: A bigger
backing plate or washers can't hurt. Your rig is small and I'm guessing that
the deck is solid glass and not cored, so it's likely it's more than strong
enough. When you cut the area away look carefully for signs of stress, cracks
and such. Add the larger backing washer/plate and do your best to make the job
look "finished." This will be an improvement to the boat.

RB