I filled the gaps on my sample board with white pigmented and thickened epoxy to see how it will look and to practice the application. After using blue tape to tape off the boards, I mixed a 5 pump batch of epoxy. A 1/2 tsp. of white pigment was mixed in and then a few spoonfuls of white silica to thicken. Then the batch was loaded into a blank caulking tube, the nozzle cut and I pumped the goo into the gaps.
The mixture was a little soupy and I ended up squeegeeing the excess off. After cure there were a couple of low spots that might be from a void underneath and the goo slumped into the void. Dunno, but overall it looks good. It definately was good to practice and have an idea what I'm going to do for real on the boat when the time comes for that step.
The pictures are of the sample board sitting on the bow of the boat.