Inner Stem, Keelson and Transom

The photo below shows my template for the inner stem. It is made from scrap plywood and is shown here in position after a bit of fine tuning. The actual inner stem can be either laminated from thin strips bent around a former or fabricated from larger pieces of timber. I have chosen the second approach because I wasn't keen on the idea of bending the laminations around the sharp radius in the stem. I will laminate the outer stem but even with its larger radius the laminations will have to be soaked or steamed before they can be bent to shape (more on that later).

Here is the fabricated inner stem with the last of the 6 pieces being glued in place. There are 2 layers each 35 mm thick with 3 pieces in each layer arranged so that none of the joints fall on top of another joint.  The finished stem will be 65 mm thick x 75 mm wide.

The transom is in place on the building jig. It is made from 2 pieces of 9 mm plywood glued together and then cut to shape. Fitting it was quite tricky because it is at an angle with its upper edge (lower edge because the boat is upsaide down) lined up with the end of the building frame. It also has to positioned vertically relative to the datum line (string line stretched horizontally above the frames, visible in the previous post). The final shape of the transom is a bit smaller than in the photo as shown by the line (click on the photo to enlarge it). The edge of the transom is bevelled to fit the planks that come down onto it at an angle.

The datum line (string) is important at the moment because everthing is positioned relative to it; the frames are vertical and therefore at right angles to it, they are all at right angles to it in the horizontal plane and are set below it by specified measurements. Once the stem, keelson and centre board case are in place the string line will be removed.

There is a rare thing in the photo, sunlight and shadow through the window of the shed! Brisbane has been very wet and dark in recent days.

Last of today's photos shows the parts of the keelson being prepared. The keelson is 30 mm x 75 mm and a bit over 4.5 metres long. It is laminated from two 15 mm thick pieces to make it easier to bend over the frames. Because I didn't have any timber long enough  the two laminations have to be scarph jointed. The photo below shows the tapered ends of the scraph joints. The 4 pieces, each 18 mm thick, are arranged stepwise on the end of the bench. Each step is 150 mm long (the length of a scarph joint should be at least 8 times the thickness of the material). Once they are accurately positioned and clamped in place the steps are planed away to form a ramp. Having made the ramp, I ran the belt sander (coarse belt) over it to scratch the planed surface up providing a key for the glue.