Step 1:
One side of the paper is yellow and the other is red.
Prefold in half over the purple lines.

Step 6:
Make sharper folding lines

Step 5:
Repeat steps 2 to 4 in this direction.

Step 2:
This is the other side of the paper.
Fold the edges to the centerline

Step 4:
Fold the edges to the centerline and unfold the model.

Step 3:
Fold the edges to the centerline.

Step 10:
Fold over these two prefolded lines

Step 8:
Press flat, see arrows and make sharper folding lines (see purple lines).

Step 9:
Fold over these two prefolded lines

Step 7:
Fold the four edges sidewards, see arrows as example. There's 1/4 square between the lines on the right and half a square between the lines on the left.

Step 16:
Make the same folds on the other side.

Step 15:
Fold the little flap on front of the boat inwards. Use glue or tape to connect the edges, see arrow.

Step 12:
Make sharper folding lines

Step 11:
Fold over these four lines

Step 14:
Make sharper folding lines

Step 13:
Fold the two corners towards each other.

Step 18:
Fold the edge downwards (=upwards in this picture).

Step 17:
Now the model looks like this.

Step 19:
Fold both rudders inwards a little.