Thanks to the guidance I drew from this forum, my first day of sanding my 16LT (w/ 80 grit) went well. With one exception. . .
Here and there, when I had sanded down just to the point at which the cloth became very faintly visible (and disappeared when splashed w/ water) *directly* adjacent to these areas (surrounded by them, in fact) instead of the desired faint appearnace of the cloth there were pinpoint white spots (these areas, 6-7 on the boat, I suppose) are maybe an inch in circumference and hold, maybe, 10-15 dots each.
My impulse was to assume (hope) that the white color indicated sanding dust that had been captured in the uppermost face of the cloth and that very careful, additional sanding would make these areas look like the clean (faintly visible) cloth next to them.
But, before sanding more, I'd thought I'd seek advice rather than do further damae (if that's indeed what I've done.)
In short. . .what are those damn white pinpoint dots???