Centerboard, Construction, Part 8: Xynole for the Trailing Edge

Two layers of Xynole applied to the trailing edge
Having become uncomfortable with the fact that parts of the trailing edge of the centerboard were not fully protected by fiberglass, but were instead protected only by coats of epoxy, I finally decided that it would be worth it to try to apply some Xynole to the edge of the board, to see if it was supple enough to lap over both sides. I had ordered a couple of yards of this high-tech cloth from Defender for some other project, but I had never used it. It was my boatbuilding neighbor who had urged me to buy the Xynole, saying that it was not only highly abrasion-resistant, but also that it conformed to many angles that normal fiberglass cloth would not.
I laid it out and cut off a strip about 6 inches in length. I could tell immediately that it was much different from fiberglass cloth. It felt more like gauze than anything else. It was hard to believe this stuff could provide any sort of protection.

Then I cut another strip about 9 inches in length.
Before doing anything else, I made sure to wipe down the entire board with acetone to remove any left-over sanding residue and any residue that might prevent the epoxy from forming a good bond.
I then mixed up some neat epoxy and wet down the leading edge of the board. Next, I grabbed the smaller piece of Xynole and laid it down and then wet it down with epoxy. I was happy to discover that the Xynole gave me no problems whatsoever when I lapped it over both sides of the board.
Notice the red dots along the leading edge. I placed these on the Xynole in advance with a red Sharpie marker. These really helped me keep the Xynole well aligned. You'll recall that I used this red-dot technique earlier, when I applied the different layers of cloth to the leading edge of the board.
Once I had the first layer fully wetted-out, I grabbed the next piece of Xynole and laid it down on top of the first.
The Xynole absorbed much more epoxy than I had expected it to. This was the most I could do at this point. What I needed to do now was to go inside and pop a cold one and let this epoxy cure overnight.
Wetting-out the Xynole was the easy part. The hard part was sanding it. Now of course sanding epoxy is never easy, but when it also involves sanding Xynole cloth, as I learned, it is hard, hard, hard. I've sometimes compared, with some exaggeration, the sanding of epoxy to the sanding of concrete. When it comes to sanding Xynole, there is no kidding on my part. It really was like sanding concrete. I might as well have been trying to sand down a sidewalk.
I used 40 grit paper, and even with that I had to work it back and forth many many times before I ever began to see any progress.
You can tell from the picture below that there was still a considerable amount of the weave showing in this Xynole. This stuff definitely needed another good coating of epoxy.
But before I could apply any more epoxy, I needed to flip the board over and sand the other side.
You can see in this close-up photo below the robust qualities of this Xynole. It was rough in texture, and it was much in need of additional sanding and epoxy.

The loose ends you see in the picture below were the toughest things to sand of all this Xynole. They were not at all like loose fiberglass threads that can be easily sanded and shaped to conform to everything around them. They were like a bunch of little rebels ready to put up as much resistance as possible before surrendering.
Eventually, I was able to gain some ground against them.
And as the fight wore on I slowly began to sense that victory was on my side. It helped to apply new 40 grit pads from time to time.

Finally, I reached the point where all resistance had been neutralized, and at that point I grabbed the acetone and wiped down the board again in preparation for applying another coat of epoxy.
I then applied the first coat of epoxy.

About two hours later I came back and applied a second coat of epoxy.

I ended the day by applying a third and final coat of epoxy. Yes, it really did need this much to completely cover the last remnants of the weave.
The next day, after the epoxy had cured, I sanded this area. It was much easier now that the Xynole had been completely covered.

Then I turned the board over and sanded the epoxy that I had earlier applied to the trailing edge.

Instead of simply re-coating the trailing edge with epoxy, I coated that entire starboard side. I did this to make up for the imbalance that existed between this side and the other, where I had applied two more total coats of epoxy. You'll know what I'm saying, if you've read the previous installments of this article closely.
Later in the day, I came back and applied the final coat of epoxy to the starboard side. As you can tell, the board was looking pretty good at this point. There was no evidence at all of that Xynole on the trailing edge, except, of course, what you could see of it beneath the epoxy.
Here's what I'm talking about. The weave of the Xynole was completely filled by epoxy. I was happy that the trailing edge of the board was now fully encased in cloth and epoxy, and there was little chance of water intrusion in this formerly questionable area.
I was now prepared to say, with some satisfaction, that the glassing portion of this centerboard construction project was complete. All I needed to do at this point was to sand the board, clean it up, and then apply two coats of bottom paint to each side. These tasks are the subject of my ninth and final part of this article on how I constructed a new centerboard for my Ericson 25.

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