After cracking the top not once but twice, I decided I needed to try a different clamping strategy. At first I tried pulling the top down into the upward sweep at the front of the board with just a few clamps. That concentrated the force right at the clamp, which caused the wood to crack. The cedar I'm using for the top is very straight-grained, which makes it very easy crack. After gluing the cracks back together, here I'm pulling the top down with many clamps and wedges. The sticks clamped across the board pull the center-line of the top down tight against the backbone of the frame, and the wedges then push the edges of the top down around the perimeter of the paddleboard. This was a "dry run", with no glue applied to the top yet, to be sure the everything would (maybe, hopefully) go right when I was actually gluing the top into place.
This is the real thing, glue and all. Lots of clamps, to be sure that the top is glued down tightly to the internal skeleton and around the perimeter of the board. Luckily, it went well.
Another view of clamping and wedging. Can't have too many clamps...
The sides of the board are covered with blue and green masking tape to keep any glue that squeezes out from under the top from sticking to the sides.
After the glue has set, the top needs to be trimmed flush with the sides and the curves all need to be blended together. I started with a drawknife to remove the bulk of the extra wood, then switched to a spokeshave and a plane to refine this area of the board.
The drawknife. I actually use two hands with this tool, but I needed one hand to take the photo. The same is true in the photos below where I'm using a spokeshave and a plane.
It's fun to plane nice straight-grained cedar. It planes easily, and you get long, fragrant shavings.
Once you get close to the final shaping of the board, then it's on to sanding. I started with coarse grit sandpaper, held against a block of wood, to do the bulk of the work. Running your hand over the surfaces as you shape them allows you to judge the "fairness" of the curves much better than can be done by eye alone. The board is sanded with finer and finer grits of sandpaper until the surface is smooth and free of tool marks and scratches. This is looking from the nose of the board to the tail.
Looking forward from the tail.
Now the board is ready for the fiberglass coating, which will add strength and impact resistance. As the term implies, fiberglass fabric is actually made of very fine glass fibers, woven together. In this state it's soft and pliable, and easily conforms to the shape of the board after smoothing it into place by hand.
Next the excess "glass" is trimmed off with scissors, leaving a couple inches hanging below the sides of the board. Only one side of the board will be glassed at a time.
Here Mark is applying epoxy to the bottom of his board. The goal with this step is to saturate the fabric with resin and stick it down to the wood. The epoxy we're using is very thin. It comes in two parts, resin and hardener. Once they're mixed together, you have about twenty minutes to work with it before it starts to thicken. You pour the mixed epoxy onto the board from a cup, and spread it around with a flexible plastic squeegee, working it into the fabric. If you manage to fully saturate the fabric and stick it down, it turns almost transparent. If you leave too thick a layer of epoxy, the fiberglass can float up into it, away from the wood, and it won't be nearly as strong as it could be.
The epoxy really brings out the beautiful colors of the cedar.
In this closeup of my board, you can see the texture of the fabric. Most the excess epoxy has been squeegeed away. In the middle of the board you can see that the dark area of the wood has soaked up more of the epoxy than in most of the rest of the board and looks a bit dry. That's okay. Another coat of epoxy will be applied after this coat has set up enough, smoothing over the fabric's texture.
The bottom of the board after a second coat of epoxy. Once the epoxy has set up a bit, but has not fully hardened, the excess fabric hanging down will be trimmed away. This is done by using a razor blade to cut through the epoxy and the fabric just above the green masking tape, and pulling the tape/glass/epoxy away from the board. If the epoxy were to harden up too much before you did this, it could be nearly impossible to cut through the epoxy/glass by hand. I'm not sure what one might do then...
(The white patch on the board is just the reflection of the fluorescent light from above.)
The top of the board after it's been laminated with fiberglass and a second coat of epoxy has been applied. Prior to coating, the sides of the board were masked off just like it was done when coating the bottom. You can see on the left side of the board where I've removed some of the masking tape and extra fabric.
As finished as the board looks at this stage, there's still a good bit more work to do on it. The whole board will be sanded smooth, to remove any imperfections in the epoxy, and a third coat applied. Epoxy does not hold up well when exposed to sunlight, so the third coat will be sanded smooth with very fine sandpaper, and the board will get three coats of UV resistant varnish.
It will probably be another month before the board is finished. I still have to install the fixture that holds the fin in place and a few other things. Varnishing will take a week or so, and then the varnish has to dry for two weeks before it's fully cured. After that, it'll be time to paddle!
I'll keep you posted...