Cabin roof fiberglass applied

With all the edges of the roof built up as described in the previous post, I gave the edges a good round over in preparation for fiberglass.  I also rounded the bottom of the cleat up in front to match the curve of the roof edge - I think that's a nice visual detail.

I cut a piece of cloth large enough to cover the entire cabin roof.  This was 50" wide cloth.

Then cut a hole in the middle for the mast trunk to poke through

And trimmed the edges to minimize the overhang there. 

I saturated the cloth with epoxy and watched the glass go clear.  I poured on the epoxy and used a 6" plastic squeegee to spread it around. 

After the epoxy cured I could trim back the ragged edges with a utility knife and then sand them with sandpaper on a wood block.

Which left things looking pretty nice.

Next I applied epoxy thickened with microballoons (tiny glass spheres) to fill the weave.  On this first coat I used the squeegee to spread it around, but on the follow-up coats I put it on with a roller, which was easier to control and gave a more consistent thickness.

Here's what it looked like after sanding.  Hard to know when this job is done.  I can still see the fiberglass cloth at this point, and that's OK as long as the surface is smooth.

It was fun to see this part of the project take shape.  This little curved cabin roof was a design feature that first caught my eye with this boat design.

Cabin roof finished (and mistakes recovered from)

With the cabin roof in place, it was now time to dress up the edges.  I could see when I positioned the roof that I would have some work to do, as things didn't line up quite right.  

First I cut and fit the doublers that go aft of B4 to see how things were lining up.  

And I believe I have made another little mistake here.  I think the cabin roof doubler should fit above the cabin side doubler, not inside it.  But I had already cut it too short to do that...  

Here you can see that I'll need to add a little material to the back end of the cabin side.

First glue-up was the cabin roof doublers on both the fore and aft edges.

And then I attached the cabin side doublers.

With the front doubler in place you can see that the cabin roof is skewed.  This looks pretty bad here, but I really can't see anything out of line just looking at the boat, so I'm not worried about this.  I did so some careful measuring of the roof panel, to see if I could blame this on a mis-cut part, but that doesn't seem to be the case. 

I think that although bulkheads B1-B4 are held with the correct spacing with an alignment jig at assembly time, I must have had some twist in there somewhere so they are not quite square with the fore-aft center line. 

So I got a bit of scrap plywood out, made one edge straight, 

and glued it on 

and after the epoxy cured I trimmed it to size and sanded it, and it looks good.  Will be invisible under the paint.

A similar pieced was needed on the aft edge of the roof

And after a bit of sanding this looks good, too.  I haven't trimmed the end here and the rear edge has not been planed or rounded over.

Next I moved on to address the back edge of the cabin sides.  Here you can see that I needed to extend the sides aft a bit. 

So I cut a piece of scrap ply to fit and installed that with epoxy.

After trimming and sanding, this looks good.  Mistakes or inaccuracies like this are easily recovered from (and that's good!).

Cabin roof installed

With the cabin sides installed and the cleats attached and beveled, the next step was to install the cabin roof.  I had been a bit apprehensive about this because of the difficulty of clamping.  

I put a couple boards across the roof and used two web straps to pull the roof to the curve of the supports.  The front strap is attached to the building jig under the hull, and the rear strap goes through the portholes and hooks into the hatch cutouts in the front face of bulkhead 4.

The straps pulled the top into the general position, but it was clear I'd have to do better to keep the top from bowing up, and to get the edges down tight to the cleat.  I decided to use screws for clamps, since it appeared to be the only option.  

To hold down the center I prepared a couple sticks and predrilled the screw holes.  For the edge of the roof I prepared a bunch of blocks to spread the pressure out.   I planed both the sticks and the blocks to the correct thickness to ensure the screws penetrated an appropriate depth. 

I applied thickened epoxy to the supports and screwed down the center of the roof, then bent the roof down with the web straps and screwed the blocks along the edge.

The blocks pulled down the edge real nice, and only one screw stripped out its hole.

 While the epoxy was curing I took the opportunity to spread the first coat of epoxy over the deck and cabin sides.

After the epoxy cured, I removed the straps and the blocks and was happy to find that nothing went 'sproing'.

I planed the edges flush with the cleats and filled the screw holes with fillet mixture. 

At the same time I filleted all the joints underneath between the roof, bulkheads, cabin beams, and sides.  Working through the bulkhead 3 hatch openings I could reach all the joints in that area also.

After the epoxy cured I scraped the nail holes flush and sanded the roof in preparation for fiberglass.  But before that is applied I will attach doublers to the front and rear edges of the roof and round over the front and back edges of the cleats.

I'm glad to have this part installed.  This boat is really starting to look like a SCAMP now.