These are cut from one strip 5/8” x 1.5” 130” long. It is split at 18 degrees. They can be of fir or pine or cypress, the important part is that they be as clear, straight grained and free of knots as you can find. They can be wet down and set with their ends supported and a weight in the middle overnight, to make bending a bit easier. Some woods 

External:

If external these are just glued and clamped to the outside bottom edges of the sides and nailed with 7/8” bronze ring nails. They can “run wild” at the ends, and then be trimmed. The other advantage they lend is when the bottom is glued on. External chine logs form a lip that the edge of the bottom can be easily clamped to. This does alter the way the leeboard is attached, as there will need to be a spacer that the pivot bolt goes through since the board will bear against the gunwale and the chine log. (Stitch and glue, or inner chine log allows the leeboard to be bolted flat to the side.)

Internal:

          Internal chine logs are another matter, but are probably the most “boaty” steps in building Summer Breeze. You get to use a bevel gauge and feel like a real shipwright! This is because we measure and mark two angles on each end using your bevel gauge. (See diagrams.) 

First the bow end is fitted and the chine is bent and temporarily clamped to the side, until you reach the frame position line. Mark where that line falls on the chine log. Now unclamp the chine log and do the same from the stern to the frame mark. You’ll now have two marks near the middle of your chine that represent how much the piece needs to be shortened to spring fit into the boat. Using your angles from one end,  shorten the piece the amount you measured between your marks. If all went well it will pop into place if not, either shorten it or we’ll fill the gap later.

          These are glued and clamped, and nailed in place. A long board with course sand paper can be used to level off the top of the chine logs. (See illustration.)

It's time to dry fit the bottom.

Now tack the bottom back in place and trace the side lines onto the bottom.

When the fit looks good trace where the sides touch the bottom. Remove the bottom and cut outside the line with your circular saw set shallow. How close you saw to the line will depend on how you intend to remove the overhang. If you flush trim with a router it doesn't much matter. If you intend to hand plane and sand, you might want to angle your saw blade 18 degrees and stay pretty close to your line. This will give less material to remove later.