Building the West Mersea Duck Punt (Episode 3)
Me as a boat builder is side-splitting!
Series by Rusty Knorr
Well, it has been a week of crappy weather and busy times with playing music and work leaving me with little time left to work on the Punt. I managed to get quite a bit done today though so here are the updates.
If you remember at the end of the last post I was preparing to do “scarf” joints on the side planks, joining two 8 foot long planks into one long 16 foot plank to make each side of the Punt. While daunting for a first timer on expensive marine plywood, it turned out to be relatively simple, although a lot of work using only hand tools. (Perhaps I see a Festool power planer in my future...) The process is just marking back from the edge a ratio of at least 8 to 1, which in my case turned out to be 48 millimeters since I am using 6mm ply. So, 48mm is close enough to 5 centimeters so I marked back on each board 5cm and then staggered them back so each edge lined up with the mark beneath it. Then it is simply a matter of cutting, sanding, grinding, routing, or planing at the angle shown and connecting the top line to the bottom front edge as you see below. The plies really give you a nice point of reference so you know where you are at with the scarf. Borrowing my friends jointer plane helped a lot but if I had to do a lot of these I think I would find a quicker way.
Of course, the next step is the glue up. I have a lot of experience with this from furniture making and it is still always stressful. I used a slow set epoxy to give me plenty of time to get things placed just where I wanted. Unfortunately, it was colder than I would have liked and I worried that the epoxy was not going to fully cure but mother nature supplied me with one warm day and so glue up happened. You have to make sure you don't clamp so hard that you starve the joint but hard enough to get things flat. a large rock, two clamps, and a 2X4 does the trick. Wax paper keeps the squeeze-out from gluing the planks to the table!
I did use packing tape along the joint so squeeze out would peel off easily but...forgot to put it on both sides of the seam. I won't make that mistake again! Still, the squeeze out is not too bad, and leads us to the next inevitable step....
Sanding. And sanding, and sanding, and sanding. Propping the joint up a bit insures I am only sanding the epoxy and not the plywood. Once the hard edge disappears, you know you are flush. When seen on edge (I wasn't able to get a decent picture) the joint is invisible. So cool!
Now it is back to using those ever so useful battens. There are several possibilities for how to hold the side panels in place while doing this but rope works for me. The side panels are cut a bit over size and the batten is clamped inside along the top (or bottom depending on how you look at it) of the frames. Then I strike a pencil line along the underside of the batten to mark the actual chine, which is the bottom edge of the boat. I guess technically the chine will be on the bottom panel but you get the idea.
Here is another view of the batten clamped in place. Hey, wait a minute! That is starting to look like a boat!!! Once the line is struck, I stacked both side panels together and using my trusty circular saw cut both at the same time to the line. A little fairing with the jointer plane and the chine is cut. Hmmmm, that little triangle area at the back is looking kinda weird...
I cut the side planks to match the angle of the bow post and beveled the post to match the angle of the planks as they come into it. And now back to that stern piece.
The stern plank is split (side splitting, get it?) and made ready to mold to the stern post, giving it that characteristic Duck Punt stern. My dozuki japanese saw leaves an almost invisible kerf, perfect for this cut.
The next step will be bevelling the stern post to match the angle that the stern planks come into it at, scarfing the bottom panels together, and then I can attach the bottom to the sides! More to come so please stay tuned, and your comments are welcome! •SCA•
I have found that a sharp scraper is much faster than sanding to clean up the scarf joints, and easier to keep from dishing out the plywood. You might want to give it a try. Works good on epoxy drips, too.
When I built my punt, I spent good money and a day's driving to get to Chesapeake Light Craft to buy several sheets of fingerjointed okume plywood. While I still needed to sand the joints, I did not need to scarf the ply by hand. I hate scarfing plywood.