Removing rail base bolts on stern of 3396

[palfvinverizon]

In lieu of replacing the hardware and railing on the stern of my 3396 (all of which are gone at this point except for the trashed rail bases), I'm trying to remove evidence of it altogether as best as I can. The problem is that the bases were bolted (not screwed) in and the base of the bolts is embedded in fiberglass.

Any suggestions as to:
* Safety of breaking into the fiberglass from underneath without having to replace/repair it
* Techniques for cutting out the top of the bolt without creating a huge hole in the fiberglass

Here's a picture of what's left at one of the base "sites" after removing the base and the head of the bolts.

Here's the underside where it's glassed in.

 

[bobalong]

Choose the least conspicuious hole. Drill a pilot hole all the way thru the fiberglass. Using that pilot as your guide, now drill a hole lightly larger than the nut from the back side and see if you can extract the nut. Screw a screw into the nut and tap it lightly. Even if you can't extract the nut, if you can get it embeded into the hole deep enough it will serve as your backer for whatever filler you decide to use. Trying to pull the nut from the top will only cause damage by puckering the hole and causing the gel coat to chip.

 

[palfvinverizon]

Now that I look more closely, I can see the bulge in the fiberglass from the foreward screw, so getting that one out will be no problem (working from inside the compartment shown in the picture). But if you look at the two pictures, you can see that the rear two bolts are over the wood that forms the frame of the rear deck. Furthermore, they seem to be positioned just outside the hull, so if I drill that pilot hole, I should come through the exterior fiberglass on the underside of the deck "lip".

Do you think there is any chance the nuts for those back two are just on the other side of the top fiberglass and not running all the way through the wood frame?

 

[bobalong]

Quote o you think there is any chance the nuts for those back two are just on the other side of the top fiberglass and not running all the way through the wood frame?

Not sure on that one. Maybe try once again in the most inconspicuous place and drill a pilot hole for the purpose of exploring what your options may be. Keeping in mind that wherever the pilot hole comes thru after it is filled it will be insignificant considering the total area of fiberglass of your boat. I would start with the smallest bit you can find. Since you will be pushing the gel coat from the back side, this will minimize popping an unnecessarily larger piece of gelcoat out. Once you have the pilot hole, use a taper bit to (forget what it's called) to make a tapered hole, just thru the gel. Just using a drill bit to make a hole sometimes causes flaking / chipping of the gel.

This exploration will tell you how, or how not, to deal with the remaining holes.

 

[palfvinverizon]

Turns out it was just through the hull. There was a "break" in the frame and once I chipped the fiberglass away to access the foreward bolt, I was able to get a wrench in to hold the nuts of the rear bolts.

Thanks for your timely responses!