When I sanded the fibre glassed hull I discovered that there were a number of tiny air bubbles on the side panels only.
They looked like this, with a rule for comparison.
I wasn't sure if this was a problem or not, so asked the vendor for advice.
They said that the bubbles were tiny and I should sand them out and coat them with epoxy.
I decided to grind them out and use fairing compound to get a flat surface before applying more epoxy. I used a small burr in the drill, like this.
This is what the ground out bubbles looked like when filled.
Here they are after sanding and a second coat of epoxy.
I also managed to sand through the fibreglass on the hull in one or two places, so I applied patches to them, like this one on a puzzle joint.
I made the patches oversized to allow plenty of room for feathered edges and to provide strength.
We're getting there, slowly but surely!