The keel bolts are used to attach the keel to the hull. All the forces of the keel are transferred to the hull via these bolts, so everything to do with them has to be done carefully. I glued thin fibreglass tubes into the holes to prevent water from getting past the bolts and into the wood of the hull. I learnt the best way to do this from Fabian (driftingdonkey.ch).
After I had drilled the holes, I had to lift the boat so that I could get to the underside.
Ich sanded little bevels at to the ends of the holes. This ensures that the ends are securely sealed and there are no fine gaps.
Next, I sealed the underside of the holes with adhesive tape and secured them with a small board.
Then the most important step: fill the holes almost to the top with epoxy, give the wood a while to soak up the epoxy (the plywood in particular can absorb a lot of resin), and then push the fibreglass tubes into the holes.
In this way, the tubes are completely glued to the wood along their entire length.
After the resin has hardened, remove the tape. You can see from the neatly filled bevels that there are no air bubbles anywhere, which shows that everything is perfectly glued and sealed.
The disadvantage of this method is that the tubes are now full of resin, which still needs to be removed with a drill. I have left the tubes extra long. The extra piece serves as a guide for the drill.
The final Result after removing the Resin and sanding:
