Filling holes in your boat left after removing bolts or screws can be hard to do with epoxy without the epoxy bubbling up or running out of the hole.
To combat this problem we mix up the epoxy and then add colloidal silica filler as a thickening agent.
You can purchase these epoxy fillers online or at a boating store such as West Marine.
Start by adding a little silica at a time until the mix reaches a thickness that doesn’t drip off of your stir stick.
Once you have the mix at the right consistency, work it into an epoxy syringe that is made for filling holes.
You should have already prepped your hole by drilling it out a tiny bit to get to fresh, clean material. Clean and degrease the hole with denatured alcohol. Put a piece of tape on the back side of the hole that you’re going to fill to give the epoxy a back stop.
Now insert your syringe to the back of the hole and begin to squeeze the epoxy out.
Withdraw the syringe as you squeeze more epoxy, filling the hole from the rear to the front. Wipe off some excess but do not wipe the epoxy flush as it will usually leave a depression in the hole. You don’t want to leave a large mound of epoxy either as it is hard work sanding it down once it has cured.
Using the colloidal silica and syringe will ensure you don’t have voids in your plug when it dries.
Once the hole is patched and sanded down you can paint it or dress the area as appropriate.