Fairing and Surfacing (Continued) Before beginning the hull fairing, I had dished out the areas around the old through hull fittings, which I had filled flush with thickened epoxy many months before, prior to beginning rebuilding work inside the hull.    In this series of photos, one through hull is represented continually (the old engine exhaust, in this case); each through hull received the same treatment.

Once these areas were dished out, I applied a single layer of 24 oz. biaxial cloth, cut into a circular shape, over the filled portion of the through hull, and extending out slightly onto the hull.  The dishing allowed the new glass to lay more or less flush with the existing outer surface of the hull; the new glass wasn't necessarily strictly required, but would reinforce the filled areas and prevent any cracking or potential failure later.

When the new glass was cured, I ground it so that the general area was flush with the hull.  Then, I applied a layer of fairing compound (left over while I was filling the hull-deck joint above) to the through hull locations, the first of a few steps required to fair these holes into the hull.

It took two applications of the fairing compound, but in the end the through hulls were smoothly incorporated into the surrounding hull, with no high or low spots.

With the coarse fairing of the hull-deck joint and the through hulls complete, I moved on to the next, rather significant, step.  I planned to skim coat the entire hull with a fine fairing compound, which would give me the base and thickness of product required to perfectly fair the entire hull and rid it of dimples, bumps, and minor flaws.

For this step, I chose a new product.  Since I had decided to try out a new line of marine LPU paint for the entire boat--AlexSeal Coatings, I selected the trowelable fairing compound from that line, a 2-part epoxy product designed specifically for fairing boats prior to application of additional products from the same line.  For the significant manual longboarding ahead, I wanted an easily-sandable material.

At some point I had read an article about a method for skim coating a hull that would make the job easier.  It made sense to me, so I decided to use the procedure.  Before beginning, I vacuumed the hull carefully, and then washed the entire hull with Awl-Prep cleaning solvent.  (All Awlgrip products are compatible with AlexSeal, and vise-versa.) After mixing up the fairing compound--a 1:1 mix of base and catalyst--I began to apply it to the hull using a 1/16" notched trowel, with square notches.  The notched trowel left an evenly grooved surface, with basically half the hull covered in a 1/16" layer of fairing compound, and the other half (the valleys of the notches) empty.  The idea behind this system is that the grooved surface, with only half the surface area, would be easier to sand, since the long board would only need to sand off the tops of the ridges.  Then, when the hull is faired in this manner, a second application of material to fill the notches would take care of smoothing the surface, subject to final sanding.

I used a plasterers' hawk to hold the fairing compound while I applied it; a hawk is a thin, flat metal plate with a wooden cylindrical handle in the center beneath the plate.  The sharp metal edge is good for scraping application tools, and the center handle makes holding the load of material fairly convenient.  With the flat side of the trowel, I applied a relatively even coat of the  gray fairing compound to the hull; then, with the notched side of the trowel, I scraped off the surface, leaving behind the grooved surface that I intended.  In this manner I worked my way up one side of the hull.

I began by applying the compound to only one side of the hull, since I thought it might be challenging to sand both sides of the hull by hand in one day.  Therefore, I chose to split the job into two separate days:  apply to one side, then the next day sand the first side and, when complete, apply compound to the other side, so that it would be ready for sanding the day after.  I didn't want to apply more than I could sand in one day, since all epoxy compounds become significantely harder to sand as the days go by.

Since the product's ideal cure temperature was 77°, before I left the shop for the night I turned up the heat to about 72°, up from the shop normal of 60°.  I wanted to make sure the material cured properly overnight. Of course, that night we experienced some of the coldest temperatures we had seen since before the shop was built.  When I arrived in the morning, I found that the heater had apparently had a bear of a time maintaining the higher temperature throughout the shop--particularly on the far side where the boat was--and that it was nowhere near as warm in there as I had expected.  As a result, the fairing compound was not yet cured sufficiently to allow sanding.  This was a real setback for me, at least mentally, as I had no other significant projects in the works to fill my time; I had expected to be spending all my time on fairing and sanding until the hull was done.  It was disappointing, but I had to wait till the next morning before I could sand the first side.  Because of the longer-than-anticipated cure time, I decided that day to go ahead and apply compound to the opposite side of the hull, since I figured that would be ready in another full day.

I found that the ridged application system worked extremely well when it came time to sand.  Armed with my 30" flexible longboard, I easily sanded one side of the hull with two different grits in only a couple hours, give or take.  By just sanding the narrow tops of the ridges, the amount of effort was cut significantely.  With the longboard, it was relatively easy to work the hull into a fair, smooth shape; any low spots were clearly visible, and my earlier work with the coarse fairing ensured that there were no significant high spots.  I coarse-sanded the ridges with 40 grit paper on the longboard, and then boarded the hull again using 80 grit to further hone the shape.

To continue, I first brushed and vacuumed the dust out from between the sanded ridges, and solvent-washed the hull to remove the last traces.  Then, I applied a second coat of the filler with plastic squeegees, pressing it into the grooves between the ridges.  I wore a respirator for most of the job, as I found the fumes from the product to be rather strong and irritating over time when working closely with the product.

After squeeging on a section, I then used the tool to scrape off the excess, so that the grooves ended up flush with the surrounding ridges; the ridges acted as a natural screed.  As straightforward as this process seemed, I was surprised with how long the job took.   I had expected it to be rather quick, but instead it took nearly 4 hours to fill the entire hull, port and starboard.

I was thrilled with how the hull looked when the job was complete, however,   It appeared to be smooth and fair, and had started to really look nice.  Of course, the surface was still slightly uneven here and there, and would require sanding and some additional spot filling to take care of isolated low spots, but it was clear that the major fairing operations were a success, and that the interesting technique using the notched trowel had worked as advertised.

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