I didn't mean topcoat, though that is a possibility... I meant to sand down the channel floor to make it smooth and remove bubbles.

I found a nice wire-brush head for my drill, so tomorrow I will try it out and see what I can do to smooth out the channel from all the unwanted bubbly features, then put on some Marine Clean, and a final (hopefully) coat of POR-15.

Now that I know what makes the bubbles, I will make certain to apply the paint sparingly!

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84 300SD - bought in April '06 with 237,000 mi