The dinghy is taking shape and it is time to flip it over and cut the rabbet into the keel. The rabbet is simply a notch in the keel where the garboard, the first plank, will connect to the keel. Most leaks occur from a poorly cut rabbet that was not wide enough, allowing water to slip by the plank and get into the bilge. It is best to think of the rabbet, not as a feature in the wood, but as a surface for a gasket that will keep water at bay. If you make a really small gasket, water might get through. If you make a larger gasket, water will have a harder time getting through.
The first step is to determine what size the keel needs to be. In our case, the keel timber is 2 3/4 inches wide and I want the keel to be 1 inch wide. This means that 7/8 of an inch need to come off of each side to place the 1 inch keel in the center of the boat.
The keel was marked at 7/8 and 1 7/8 and lines were drawn the length of the keel. Following these lines, I made the first cut proud of the line with my skill saw. The deepest I can cut is 2 3/8 inches, so my cuts were precisely that depth.
A proud rabbet was cut into the side of the keel to meet with the first cuts I had made. This allowed me to remove the piece of wood from each side of the keel timber to begin the actual trimming process where I refine the keel into its desired shape.
With the wood removed, I then began cleaning everything up with a No. 4 Stanley plane. This let me carefully bring the proud cuts right to the line without any risk of going past the line. The rabbet line was drawn a full 1/2 inch higher than where it is going to end up that way I don't go past the point. I cut down to the rabbet with no bevel just to get it down to the right location.
Once at this point I set a batten on the frames and looked at the bevel it needs to lay flush against the rabbet. This work was much more tedious as each frame has a slightly different bevel. The bevels between frames was recorded based on the chine log.
The end is a sloping curve where the rabbet is beveled in such a way that all the planks will run flush along the keel and frames. The middle of the dinghy is more flat while the ends are rather extreme. The bow was very radical as the planks come down at a very sharp angle.
After the bevel was set on the keel, the rabbet plane was set using this side as the reference and the rabbet line was cut into the keel. This worked well everywhere except the forefoot where the plane didn't fit and had to be cut using a chisel.