To get an overview watch the video

Some explanations:

First, sorry for my English.

I built this boat for a 2x4 contest. The rules said I can use a real 2x4 , so my 2x4 was 5cm x10cm and 8 feet (240cm) long. The rules said also I can use 10% other material, this is the reason why I covered it with this ugly plastic bag and I used duck tape so I can remove the plastic bag easily after the contest. The design was really bad and I do not recommend it. I made no plan only a little model to get an idea what it should looks like.My biggest mistake was to use a extra board for a seat. Without this seat it should be much better. The weight of this boat is 6,7kg.

Step 1: Sawing

I cut the bar in many thin stripes

The thickest was 8mm and the thinnest was 2mm

Step 2: The Back Frame

The back frame was made with half lap joints.

Step 3: The Side Bars

I cut very thin stripes, I drilled holes in a board, put wooden dowels in and glued 3 stripes together

Step 4: Put the Frame Together

I put the bars in the right position and cut them in length

I glued and screwed everything together. Later I replaced the screws with wooden dowels.

Step 5: the Crosspieces at the Bottom

The crosspieces at the bottom are simple butt joints

Step 6: the Crosspieces on the Side

For the crosspieces on the side I used two piece of paper, put each of them on a bar and sticked them together with tape. I transferred the form to a piece of wood, cut it, sand it and glued it on the frame.