I decided to make an attempt at fabricating a waterway using inexpensive basewood. No harm in trying!
It was immediately apparent that a piece of this thickness would be difficult to bend. So I began by tracing the pattern of the original waterway onto the wood. I cut the piece out (roughly) using a coping saw. Then I sprayed a bit of adhesive on the piece and stuck the original waterway on top of it. Finally, I removed most of the excess material using a sanding belt and hand sanded the remainder down to nearly exact size.
Once the piece fit in the boat, it was now apparent that the curved shape of the hull was going to require a bit of bending, but this could be improved by shaving some of the wood from the hidden corner of the waterway that will never be seen. Doing so enabled most of the piece to fit flat, though the fore end would still require some force to bend it in place. Perhaps I would have to resort to fabricating the waterway in three pieces instead of two as shown here. For now, I decided to continue the experiment.
I marked a line along the top centerline of the waterway with a sharp pencil. I placed the original waterway next to the new one and marked a line at the height of the deck. With these two lines in place, I hogged away most of the material using a sharp blade. Once it was close, I sanded the angle down until the marks just began to disappear.
This worked out pretty well on the lengths but it became a bit inexact at the front and quite easy to make a mistake. It would in fact probably be wiser to make this in three pieces using the original parts as a pattern, as the fore section might require several attempts.
I've laid out some planks next to the scratch waterway. We can see here that the first attempt was quite close, though a little more adjustment would be necessary to match the original planks (alternatively, the original planks could be sanded down to fit the waterway).
