
Start by drawing the cabin as a fat rectangle. Don't worry about an exact measurement; just try to keep it somewhere between a square and twice as wide as it is tall.


Cut the rectangle in two horizontally.


Extend the line you just made a little ways past both sides of the rectangle. Finish the roof by connecting the ends of the line to the top corners.


Make a door to the cabin by adding a rectangle somewhere towards the middle of the bottom rectangle.


Make sweeping arcs from the bottom corners to start the bow. The ends of these lines should be even and a little bit higher than the corners they start from.


Use another set of long shallow arcs going from the ends of the arcs you just made down a little farther than the cabin is tall to finish the ship itself.


Add rolling waves at the bottom.


Tidy up the lines a bit and you've finished your ark.
