The scantlings provide the structure to which the boat will be put together plus they help define the boats shape. The Sides took a little more thought to determine the best looking shape, while utilizing only a single sheet of plywood per side. The engine shaft length had to be taken into consideration, and it’s while thinking these over when we decided to go to a 20″ shaft length engine (as a 15″ would leave the Sides too shallow). With this in mind, the following drawings were used to sketch the boat, but they are used just for a starting point as this may change based on what we see as the build continues.
Initial Shape (note engine is not scaled properly due to cavitation plate)
Once the shape is generally know, we can define the minimum length of the ribs, minimum because we made them long as they would be trimmed to size afterwards. The ribs are made from 7/8″ x 1-1/4″ white oak and the length several inches longer than needed. The chine shape is cut out at the bottom with 3/4″ removed from the bottom (you don’t want the ribs in contact with the floor as it will catch debris). The best practice for cutting out the chine sillouette is on the table saw using a repeatable method. A counter sunk hole was drilled 3/4″ from the rib bottom for eventual chine attachment.
The boat was flipped to attach the ribs (and the eventual sides). The rib location was marked every 16″ and the line translated down the chine and to the bottom (this bottom mark is needed to find screw locations after the plywood sides are put on). The ribs were dry-fit on the chines and drilled (we through drilled it as the hole gets filled anyhow). After drilling was complete, all the ribs were permanently attached using PL Premium.
There are 2 frames on this skiff that provide some lateral stiffening, which will be essential when wrapping the plywood sides on. The construction of frame is created by combining several different components: a pair of ribs (side frame), a horizontal floor frame and a pair of knees. The frames were placed at the 4th and 7th pair of ribs (from the back).
The floor frame was the first piece to be constructed. It spans the boat’s width and the ends have a compound angle, with an angle of the rib (as viewed from behind) and the angle of the rib due to boat’s curvature (as viewed from above). This floor frame was cut long, then trimmed iteratively until perfect fit. Once fit satisfactory, the scuppers were cut so the skiff can drain rain water effectively. The knee was made to fit between the floor frame and the rib. The rib side of the knee has the same compound angle used to cut the floor frame. That floor frame and knees were assembled using Titebond II and 2″ stainless screws and then all exposededges were rounded over with a router. The assembly was then installed using Titebond II and stainless screws up from the bottom (4″ spacing).
The transom was provided a little more support by installing the transom knee and outboard stiffener plate. Again, the knee was provided a scupper.