How To Build A Catamaran

The Hull

As mentioned, a catamaran has a specially designed three-part hull. It consists of two pontoons and a deck joining them.

1. The size of the pontoons are generally 6 inches long, half an inch wide and one inch tall. Make them as long and spaced as wide as your regatta rules allow.
2. Cut the pontoons from a light wood with the grain along their length. Two or three thin pieces of wood may be cut to the same shape and glued together (laminated) to produce each pontoon. If three pieces are used, weight wells can be cut in the middle piece.
3. The pontoons should be rounded like a bullet in the front and tapered in the back.
4. Most of the length of each pontoon should be full width and height.
5. If this size is used, each pontoon will displace about 1.6 square inches of water.
6. The more identical the pontoons are the better.
7. The deck size is about 3 inches long, 2.5 inches wide and an eighth inch deep.
8. Cut the deck from a light wood with the grain along its width.
9. Sand each of the three parts to shape with a medium grit sand paper (60 or 80).
10. Using wood glue, glue one pontoon along the edge of the deck. The rear of the pontoon may stick out half an inch or so for a better look.
11. Sand the edges of the deck round with a fine grit sand paper.

The Sail

1. Make the sail of rigid materials.
2. Make the floor of the sail flat so it will be easy to attach to the deck.
3. Make the wall of the sail an inch to an inch and a half deep, depending on how hard you can blow. More breath, more depth.
4. Make the roof of the sail at an angle near -20 degrees.
5. Place the sail at the very end of the deck. It is best to seal it with liquid plastic before attaching to the deck.

Point of Balance

Placement of the balance point is a key to the success of a catamaran. Too far forward and the nose will bury itself in water. Too far back or high and the boat wants to wheelie the whole race or worse yet, flip over backwards!

1. Make the weight of the boat as near the lower limit of legal weight as possible with your materials. The harder you can blow, the heavier your boat can be, but it will be slower than it would have been if it weighed less!
2. Place half of the free weight just rearward of the center of each pontoon so the nose tilts up about 5 degrees.
3. Place the weight low in each pontoon to increase sideways stability. Place it higher (but NO higher than the center of the sail) if you want less nose-down tip when you blow. You may want to experiment with this trade-off.