I use 7/8" x 3 1/4" pieces of maple dowl stock (Home Centers / Hardware stores)

First I drill a 1/2" recess on each end about 3/8 inch deep. I use a hand drill with the dowl piece in a vice. It's best to do this first to avoid drill chatter.

Then I drill in from each end with a 1/4" bit. You now have a channel hole through it.
Now you have a dowl with a recess and a channel through it. If you'r off a bit don't worry just ream it into a channel with the drill.

In the drill press (or by hand) you drill two 1/4" drill holes in the center that connect to the channel. You file them together making an elongated hole.

To fasten it, you snake your line in from one end and with a piece of wire with a hook on the end, grab it an pull it out the center hole. Run it through the boat and push it back into the elongated hole. Grab that with the hooked wire and pull it out the other side. Adjust your length and tie two knots that get hidden the recesses on the ends. Burn your knot ends so they stay tight.

That's basically it. I use a router and drill press and other things to enhance the craftsmanship, but you can do it all with hand drill .