Centerboard, Construction, Part 6: Glassing the Starboard Side

The starboard side, sanded and prepped for glassing
While the fifth part of this nine-part article on the construction of a new centerboard for my Ericson 25 concerned the application of Kevlar and biaxial cloth to the leading edge, and the application of two layers of 10 ounce fiberglass cloth to the body of the board on the port side, this sixth part simply concerns the glassing of the body on the starboard side. I use the word simply with some caution, because there was little about this whole centerboard construction project that was simple. What I mean, though, is that this stage of the project required less thought and more grunt labor than any of the other previous stages.

What you see below is the port side of the board with its many coats of epoxy, fully-cured. The sheen on this side of the board had to be removed before I could do any other epoxy work. I would be laying down two layers of 10 ounce fiberglass cloth on the starboard side, and a fair amount of this cloth would be lapping over all of the edges of the board, except the trailing edge. For this reason, I needed to scuff up the epoxy on the port side so that the new layers would have something to which they could cling.
Before I could start sanding this port side of the board, however, I needed to cut off the excess cloth that was stuck to the plywood adjacent to the trailing edge of the board. This I accomplished rather quickly with a razor knife. It was getting to be late in the day, so instead of sanding this side of the board this time, I decided to do what I could in terms of prep work for the other side.
I began by flipping over the board (very carefully I might add) and snipping away all the fiberglass needles that were sticking up all over the place. These needles were the stiff remnants of stray pieces of fiberglass cloth. The aviation snips that I used for this job and for the cutting of the cloth (in Part 5 of this article) made for easy work.
Here's a better shot of those needles. Not the sort of thing you want to get your hand near.
I also had to do some more trimming of the excess cloth along the trailing edge. As I said in Part 5, my goal was to allow the cloth on this side of the board to overlay that little excess part from the other side. This, I thought, would create one solid piece of fiberglass along the trailing edge, and this solid fiberglass would protect the foam from water intrusion.
The foot of the board proved to be problematic in terms of the overlaying of the cloth. It was doubled over, so it was difficult to have the same, consistent excess edge along the trailing edge.
Another relatively simple task that I needed to undertake before I could glass this side of the board was to patch the area at the head of the board that was missing its foam. As you might recall, I had knocked out a chunk of foam when trying to shape this area with the electric handheld planer. To accomplish this task, I mixed-up a small batch of epoxy and colloidal silica to the consistency of peanut butter and daubed it into the damage area. This was the most I could do on this afternoon after work, so I had no choice but to let the epoxy in this area cure overnight.
The next day, late in the morning, I pulled out the grinder and started to take down the rough edges of the epoxy on the patch job.
By the time I finished, I could hardly tell that it was a patch, unless I stared at it.
Then I took the grinder down to the foot of the board to get rid of some of the little folds and lumps in the cloth down there.
It was faster and easier to grind first, and then sand, rather than just sanding.
I tried for a while to use the sanding block that I had used during the shaping process. It was no match for this epoxy, so I quickly abandoned it.
The grinder, at this point, was the only way to make significant progress.

Eventually, I was able to get the edge of the cloth down to the same plane as the foam.

Satisfied with the smoothness of the starboard side, I flipped the board over and began to grind the port side.
Given, however, that this side was far smoother and thus much less in need of such harsh treatment from the grinder, I soon put the grinder aside.
It its place, I used the random orbital sander with a 60 grit piece of paper. This would do okay, but I would eventually replace this with a 40 grit piece of paper. That did the trick.

Satisfied with the port side, I flipped the board back over to the starboard side, so I could do some prep work for the glassing that I would do the next day.
First, I wanted to make sure that I was not in danger of exceeding the 2-1/4 thickness threshold. You'll recall the following: that the finished thickness of the old board was 2-1/4 inches; that I had constructed the mold for the new board to a thickness of 2-1/4 inches; and, that after removing the board from the mold, I had had to sand it down by 1/8 inch on each side to reduce the total thickness to 2 inches. I needed to do this, of course, to allow for the build-up of cloth and epoxy on top of the foam. To gauge my progress, I set the calipers to 2-1/4 inches.

First, I measured the thickness of the board at the pin-hole. This had to be 2-1/4 inches, since that was the length that we had cut the stainless steel pipe that formed the pin-hole shaft.
I then drew the calipers along the leading edge of the board. It's difficult to tell from this picture, but there is at least 1/8 inch clearance. This was good, especially since I had more cloth to lay down.
After hitting this side of the board with the Shop-Vac to remove sanding dust, I wiped everything down with acetone.
Then out came the 10 ounce cloth.

I applied red dots to the edge of both pieces of this cloth, just like I had to the pieces of cloth on the other side. This would help me when the time came to drop the cloth on top of the epoxy-saturated board. The dots would serve as reference marks for keeping the cloth well-aligned. It was mid-afternoon at this point, and I knew there was not enough time in the day to apply the epoxy, so I called it quits.
The next morning, I started by uncovering the board. I always made a point to cover it at night in case in rained. Normally, I also covered the blue tarp with a white sheet to reflect the sunlight, but I knew I would be starting early the next morning, so I skipped that part.
Just as I had done on the other side, on this one I fully saturated the body of the board with epoxy thickened sightly with colloidal silica. Then, I dropped the first piece of cloth down on the board. This I managed to do by myself, but not without difficulty and not by choice. The Admiral had had to run a quick errand when I started the saturation process. She had planned to return in time to help me lay down the cloth, but she got delayed by our not-so-quick youngster, who was hanging out with some friends. I would have had a much tougher time with it, if I had not had those red dots as reference marks to help me line up the cloth on the leading edge.
The Admiral did arrive back in time to help me with the second piece of cloth. She also helped me make the necessary cuts at the bend in the board near the eyelet and in a few other areas where the cloth needed to make unusual turns. She would cut and I would apply the epoxy, with the pot in one hand and the brush in the other. After we had gotten past this nit-picky stuff, I filled up the weave of the cloth as much as possible with neat epoxy, i.e., epoxy containing no colloidal silica.
About an hour and a half later I returned and re-coated the cloth with epoxy.
I did the same thing about one and a half hours after that. This would be the final coat I would make in this part of the process. Something came up and I was not able to apply the third coat, as I had done when I was working on the port side of the board. That was okay. I would make up for this unequal treatment later.
I was pretty pleased with the patch job at the head of the board. You could see the cured epoxy-and- colloidal-silica mixture beneath the cloth in all of its whiteness. Once the time came to apply bottom paint, this patch job would forever disappear.
While it might seem that this would conclude this article on my construction of a new centerboard for my Ericson 25, there was actually a good bit of work that remained. I still needed to sand and fair the board, and I still needed (although I did not realize it at the time) to apply two layers of Xynole cloth to the trailing edge of the board, and then re-sand, and then apply bottom paint. These remaining steps are the subject of the final three parts of this article.

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