Friday, August 3, 2007

Bagging the port daggerboard case half

I got good news from Ian: he told me not to worry about the foam on my starboard case half butting out a bit too far, that I can just flatten it out with putty when I join the two halves and this would distribute the forces just fine. That was quite a relief, so I moved on to the port case half. This one is of course more interesting since it has the rope channel relief to contend with.

First I attached the rope channel mold to the case mold, and trimmed the foam to fit around it:

Off to the left in the picture above are the thick lengths of masking tape that were used to form the taping rebates for the starboard case half. I was able to re-use them for the port case half which saved some time.

Per the suggestion in the plans, I was originally going to use modelling clay to form the radius between the rope channel mold and the main case mold, but it turned out harder than I expected to get a nice smooth radius with the clay:

Even though this will be inside the case and never seen, I decided I could not live with it like that, and instead resorted to a good old-fashioned epoxy putty fillet:

The mold can certainly be re-used for a port half like this, and the rope channel might even pop off with the fillet intact since it is laying against the tape on the main mold.

Thursday evening, after the putty was cured I finished taping up the mold and started getting ready for the lamination\bagging procedure. Here I'm getting ready to cut the bagging film to size, taking into account the height of the mold itself:

I didn't have time to do the lamination Thursday evening, but I did pre-cut the rest of the bagging consumables.

Next, after work today I pre-cut the glass reinforcements and got things ready for the lamination and bagging. Here I'm trial-fitting the first layer of A:

When I did the starboard case half, I laminated the case side glass as it lay vertically against the mold. This is a pain in the rear, because gravity wants to pull the epoxy down onto the melamine board and it gets all over everything. For this case half I did something different: I flipped the side glass up on top of the mold, wet it out in that position, then flipped it back down. This was much easier and worked well (you need to be careful with the glass when flipping it back down, of course, since it's fragile at that point):

Here's how it looked with the first layer of uni and the extra half-section of A in place:

At first I was continually trying to get the glass to lay tightly around the rope channel mold, but it wasn't having any of it - that's why it looks so bubbly on top of the rope channel in the picture above. I gave up on it after awhile, and am leaving it up to the vacuum pressure to whip the glass into shape. However, once I got the foam placed that did help pull some slack out of the glass and push it down into the radius:

The plans don't say anything about it, but I was mildly worried about the gap between the rope channel mold and the foam. It would be almost impossible to pre-cut the foam to make a perfect fit with the wetted-out glass in place. So what I did was mix up a quick batch of putty in the middle of the lamination and filled in the gaps around the channel with it:

You can also see the second layer of uni in the picture above. Next layer was the final large piece of A glass. I laid it in place and wet it out moving from from one side to the other. When I was down to the side glass, I trimmed it to fit (I had left it too wide on purpose, since it was hard to know in advance exactly how wide it needed to be):

Now I was almost done with the laminating part of the job. All that was left was adding the extra rope channel reinforcements:

Finally it was time for peel ply, release film, breather fabric, the bag, and turn on the pump:

The seal turned out pretty good; it gets up to 25lbs and the pump only kicks on about every twenty minutes. My wife helped me fix the leaks, she's getting pretty good at it.

You might note that I didn't put peel-ply down against the mold again. This time it was intentional, I decided that I preferred the nice smooth surface left by the bare mold, since I do plan on painting the interior of my daggerboard case. After seeing how hard that Alexseal polyurethane paint cures, I'm curious to see how well it holds up to being banged on by the daggerboard someday.

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