Skim Coat:  First Sanding After the second coat of fairing compound had adequate cure time, I attacked the task of sanding the hull smooth.   The second coat was slightly lower than the raised ridges of the first coat--screeding the new material off  tightly with a squeegee had actually pressed the new material a bit lower--so the chore was to sand the areas flush with each other.

The ridges proved to be more resistant to sanding than I expected, having had a number of days to reach a full cure, but over a period of many hours (most of the day, in fact), I sanded the hull flush and smooth without compromising the fairness left behind by the initial filling and sanding earlier.  I sanded the hull as far as 80 grit for the moment.

The first sanding identified a few low areas left behind from the filling, as well as some grooves that had not been entirely filled.  Therefore, a third filling would be required.  It was too late in the day to deal with that, so I left that for another time.

I had to be away from the shop for pretty much all of the next day, but the day after I returned and applied a third (and final) coat of fairing filler to the low spots on the hull, filling in the lows, pinholes, and any remaining unfilled grooves.  There ended up being a surprising number of these pinholes and low spots, many of which I hadn't noticed during the initial sanding because they filled with dust; when I vacuumed and cleaned the surface, however, they came to evidence.

The next day, I sanded the filled areas smooth and flush with the surrounding hull, and then sanded the entire hull to 120 grit, which was the appropriate smoothness required as a base for subsequent coating steps.  I also featured in the bottom edge of the filled portion of the topsides with the existing hull, just below the waterline.

Interestingly, I received a telephone call from Christian von der Heyde at AlexSeal Yacht Coatings, who had been informed of my using the AlexSeal products by my supplier.  He had a concern over my choosing the notched trowel method to apply the skim coat of filler; it seems that the lines left in the material when using this method, because of a variation in density between the applications of material, had caused print through issues in previous cases, particularly when used under dark hull colors.   Of course this was of concern to me also, as I had not considered such a possibility.

After some discussion, and my relating the details of my particular installation, we determined that it would probably be OK to proceed as planned, and that the drastic (and unthinkable) step of removing the material did not need to occur.  Later, I made a very critical evaluation of the filler job on the boat and decided that I had no choice but to continue down this previously-chosen path, but that the end result would likely turn out OK.

I planned to apply the appropriate thickness of high-build primer over the filling compound, then sand, fair, and smooth as needed before applying finish primer.  A guide coat of dark, glossy paint, used after final priming, would help determine any remaining flaws or print-through issues in the hull surface; with bright white planned for the final topcoat, I guessed at a high probability of ultimate success in the final coating.  Nonetheless, this education was an eye-opener, and I truly appreciated that Mr. von der Heyde had taken the time to call and discuss the issue with me.

Next:  high build primer.  Continue>

 

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