Here I have cut out the bottom for the boat along the lines that I drew from the plans. At this point I did things a little different then Devlin called for. I used some slightly thinner wood for the bottom to make the boat lighter. I only did this because I am a fairly small lightweight guy. For most folks I would not recommend this.
The cuts on this bottom panel where done on a beveled angle. This is so that when the sides are fitted to the bottom at the appropriate angle that the surfaces will meet up nicely.