Re: Repairing Pencil sized hole in hull
Take a 1/2" drill bit and chamfer the hole edge so it is cone shapped (do not drill all the way through). This can best be done by holding the bit in your hand or using a simple T handle chuck to hold the bit. Doing this gives a larger edge/area for the epoxy to hold onto than just a hole and exposes clean surface.
After that if you have access from inside, cover hole with tape, then fill hole from outside with Marine Tex epoxy. If the epoxy is too thin to hold, either wait a little while until it starts to set and it will thicken a tad and you can put it in like paste, or mix in some plain old cooking flour to thicken it up right away.
After it is set, sand smooth. Another coat may be needed to make it fully smooth.
Touch up with paint or gel coat as you see fit.