Bow eyes are commonly through bolted, and often glassed over as well, so simply backing out the bolt may not work.
Having a DS1, I was lucky to have the top half of the forward space not enclosed (it's not really accessible, but it is possible to wedge in to replace an bow eye. With mine, I didn't have to remove any glass, but I think there was a bit of backing plate glassed in, but nothing that had threads (or didn't have threads any longer - the bow eye could have been factory original, but it could have been replaced at some point - impossible to tell).
There's quite a bit of discussion of bow eye replacement among the older posts. For starters, you might look
here and
here.
Some people are partial to using the stainless U-shape bolt with two nuts, I ended up using the single bolt chrome plated bow eye and it's worked for so many season and so many times of loading the boat (the number is well in the hundreds by now) that my conclusion would be that it's not a reckless replacement.