Trying to fill holes

Hi everybody. New to the forum here.

Last year, I bought an old fibreglass canoe off of kijiji. The boat needed some TLC, and I gave some to it. This season, I’m trying to change the old aluminum gunnels to vinyl. Once I removed the aluminum, I realized that the new vinyl gunnels don’t cover the old holes from the previous rivets, the new gunnels sit too high.
I’ve tried to fill the 3/6" holes with epoxy putty, and I thought I had success, but after a day or two, I’m noticing the putty wants to pop out.
Any thoughts on what would be a better solution?

Thanks in advance

Congrats on this project!!

Is there a reason you didn’t try to place a layer of fiberglass or similar inside then fill with something like gelcoat?

Is the boat painted? It looks like the gunwale area has irregular thickness. I also see fraying, cracking or other damage along the top edge. If that’s just dirt, I’m sure about the next thought.

I suspect the holes were not cleaned out. Thus the putty did not bond. Is the putty one or two part?

Thanks for the response. For the first few holes, I placed a piece of fibreglass over with resin, but the bit of resin I had hardened up too quickly. I had the epoxy putty available to me, so tried it.
Getting supplies from the stores during the lockdown takes a while, so I figured I’d go with what I had.
I do have a small can of gelcoat, but have no experience with it. I’d say the thickness of the hull is around a 16th of an inch. Would gelcoat fill this after I placed the fibreglass on the inside?

I painted the boat with Tremclad last year. Once I pulled the aluminum gunnels off, this is what I found. It has been cleaned with water, then acetone. Maybe I didn’t pay enough attention to the inside of the holes though. The putty I used was two part.

Thanks again guys, for your responses. I figured I’d have the old gunnels off, and new ones on in one day. This has become a long, but enjoyable fix.

Gelcoat…a small can…gelcoat is two part without specific hardner .second can…worthless.

Even “fast” epoxy hardner has a 10-15 min pot life… if mixed properly. Without metering pumps you have to measure exact volume ratios.

Epoxy needs clean, dust free solid surfaces to connect to.

It might bond with paint…then the paint flakes off. Bad…

Personally I’d do a lot on this you might not want to do. So a cheap attempt would be to over drill out the holes…take a 3/16 hole to 1/4". Wipe the surface with denatured alcohol. Fill with new epoxy putty. Make fill more than flush…it shrinks. Paint after 48hrs.

Of course you could always just put in a pop rivet in each hole with some sealant to keep water out.