Paper Catamaran

Cut and fold a sailing catamaran for your nearest "ocean". It can carry a crew of ants, pepples, or some of your sister's favourite (miniature) dolls.

You will need a pair of scissors and an A4 80g/sqm office paper. (No sweat, the design can modified for inferiour formats.) No glue or tape is needed. ...nor batteries.

Step 1: Print or View the Drawing, Cut the Paper to Pieces.

The PDF-file provided below contains a drawing.

The drawing is a high precision machine drawing prepaired with programs used by NASA. If it is followed carefully, all parts will fit nicely together. For these reasons, it is recommended that the first one or two boats you make are built from printouts of this file.

Don't cry if you don't have a printer. The design is perfectly possible to follow just by viewing the drawing on your screen.

We start here by cutting the pieces apart along the solid lines. If you want fins, cut them out too. If not, you can leave them where they are. They can be used as a foredeck if left attached to the sail.

Step 2: Prefabricate the Easy Parts

We warm up by making the simplest parts.

The beam is folded up-down-up-down...
The slits that will accept the hulls are most easily cut when the beam is completely collapsed.

Note that the drawing shows two fins -- fixed rudders -- that can be cut out from that quarter of the paper. The pictures, however, show the original design without fins.

Since the fins will be folded into the hulls, now is the time to decide if you want them or not. For simplicity, leave out the fins the first time. (To be perfectly honest, I have not tried them out on the water, so I cannot tell if they will make any perceptible difference. The original design does not keep a straight course downwind, so it may pay off to experiment with them.)

Step 3: Fold the Hulls

The hulls are designed as a "V" section with two watertight ends.

Pay attention how the outer edges of the paper are folded inwards (inboard) and lock the tab that was was formed as a consequence of making the sloping bow.

Eh. Better yet. Don't pay attention to the above explanation. Look at the pictures and follow the fold direction information coded by the line types.

Step 4: Connecting the Hulls With the Beam Structure

Collaps the beam structure, open the hulls, and insert the hull sides into the beam slits. Carefully expand the beam again. With some magic (and friction) we now have a stable platform for our sail.

Step 5: Adding the Sail

This step is a bit tricky. You may have to sharpen your fingers in a pencil sharpener, or train a few times with A3 papers (or larger).

The lower part of the sail is slipped into the cut in the hull. The cut in the sail support structure should then lock the sail to the hull so that it cannot fall over forward.

The cut in the hull is placed so that the lower corner of the sail coincides with the (inside) of the knee of the bow. This prevents the sail from slipping forward and then out of the grip of the interlocking cuts.

Step 6: Ta-daa! Done!

Your boat should look something like this. Time to run to the park with Rover and some of those kids you should not play with.

Final note.
The drawing/file has been prepared for the length:width ratio of the A-series paper formats. A simple stretching or compression of the drawing in one of the directions will not produce a working drawing for other paper formats. The drawing can, however, be elongated, or shortened, in the mid-section of each part.

If you learn to build the boat without the use of the drawing, different paper formats will not bother you at all.