MANILA, Philippines—With floods expected to last a few more months in the foreshore towns around Laguna Lake, there is a need for a simple boat to ferry people and goods through flooded streets. The boat should be capable of being pulled, poled or paddled through the water. It should be light enough to be carried above obstructions or the occasional shallow water, but can still take a good-sized load.
Called PHBYC bahangka (short for pangbaha na bangka), the boat has been tested for load-bearing capacity and stability. Capable of carrying up to six people, it is practically unsinkable because of its flotation chambers. However, it should not be used in strong currents.
Easy to build for P2,500
Technically a punt (flat-bottomed boat), the bahangka is cheap and easy to build, with minimal waste of materials. It can be built using simple hand tools like a saw, hammer, plane and measuring tape at a cost of about P2,500.
The boat was designed by members of the Philippine Home Boatbuilders Yacht Club (PHBYC), the only organization of home-boat builders in the country. The PHBYC (www.pinoyboats.org) has built 18 bahangkas with the help of its sponsors, Cord Chemicals, Philippine Wood Producers Association, Polymer Products, and Designs Ligna, and distributed them to various Red Cross chapters and local governments.
Follow the instructions below to build your own PHBYC bahangka.
- 2 pieces, ¼-inch marine plywood (actually 5-mm thick) for sides of boat and flotation chamber
- 1 piece, ½-inch marine plywood (actually 10-mm thick) for the bottom
- 5 pieces, 1x1 kiln-dried tanguile or lauan for battens
- 2 pieces, 1x2x8 kiln-dried tanguile or lauan
- 1 piece, 1x2x12 kiln-dried tanguile or lauan
- 1 liter of epoxy glue, ½ kilo of ¾-inch common-wire nails, 1 gallon of epoxy or enamel paint
Cut the ¼-inch plywood using the cutting guide for the sides. (Illustration 1: Side panels cutting guide).
||Illustration 1: Side panels cutting guide (click to enlarge)
Stack 2 pieces of the 16-inch-wide plywood and 2 pieces of the 12-inch-wide plywood. Level them at the rear and bottom. Cut the front of the stacked pieces at a 45-degree angle to make the sides of the boat and the sides of the flotation chamber. Cutting all four pieces together will ensure that all parts are exactly the same.
Stack the 12-inch-wide piece against the 16-inch-wide piece which you cut for the sides and draw a line on top of the wider piece. This line will show where to put the battens (wooden pieces used to attach plywood). Draw the line on both sides of the 16-inch panel, and for both sides of the boat.
Glue and nail the 1x1 battens on all four sides of the 12-inch-wide flotation sides. Glue and nail the 1x1 battens on the bottom, front and rear sides of the 16-inch-wide side, including under the line that you drew. On the top side of the 16-inch side, glue and nail the 1x2 batten, opposite the side of the 1x1 battens.
Make sure that when you put the battens, you make mirror images. You don’t want to make both left sides of the boat. Do the same with the flotation chamber sides.
The glue should be mixed thoroughly. Mix just enough epoxy that can be used in 15 minutes. Nail the plywood to the battens approximately 6 inches apart. Only the glue will make the joints waterproof, so make sure that you apply it liberally and that all joints are filled.
Cut the bottom panel as shown from the ½-inch plywood (Illustration 2: Bottom-panel cutting guide). Draw two lines on the bottom panel, exactly 12 3/16 inches from the sides. Glue and nail the flotation sides to the bottom.
Illustration 2: Marking top of flotation chamber on boat sides
The plywood side of the flotation panels should be to the inside of the boat, with the battens facing outward. Then glue and nail the boat sides to the bottom, with the battens to the inside of the boat. (Illustration 5: Cross section and elevation of boat)
||Illustration 3: Battens on flotation sides
Fit the flotation baffle (compartment side) to the insides of the flotation tank. The baffle is added protection. In case one or several of the cells inside the tank are punctured, there are other watertight cells to keep the boat floating.
The 48-inch by 16-inch panel cut from the plywood sheet that made the side panels will be used as the rear transom (front or rear panel). Again mark a line 12 ¼ inches from the shorter sides of the panel. This will show where the flotation sides should be. Glue and nail the rear transom to the sides and flotation sides. Put additional battens for the plywood to be nailed to so as to unite the bottom with the sides and the top of the flotation.
Illustration 4: Bottom panel cutting guide(click to enlarge)
||Illustration 5: Elevations of boat
(click to enlarge)
Hand plane or sand paper
Use a hand plane or sand paper to make a 45-degree angle on the bottom panel in the front of the boat, to ensure that the front transom lies flat. The remaining 16-inch by 48-inch-piece cut from the side-panel sheet will serve as the front transom of the boat.
But since this panel is short by 6 5/8 inches, the balance will come from the plywood sheet from which the bottom is cut. Nail a 1x2x4-foot piece of wood to the inside of the boat to serve as butt block.
Finally, nail a 4-foot length of the 1X2 batten to the top of the front transom. Use epoxy liberally on the joints for water tightness.
||Illustration 6: Rear transom nailed in place
Split a 3-foot length of a 1x2 wood at a 45-degree angle to make two pieces. Use the pieces as battens to mate the bottom with the front transom. Also put battens on the top of the flotation chamber.
Paint the inside of the flotation chamber to protect the wood, except for the battens on which the cover of the flotation chamber will be nailed. Once the paint is dry, cover the flotation tank with the two pieces of 12-inch by 92-inch plywood.
||Illustration 7-Front transom nailed in place
Color of choice
Paint the boat in the color of your choice. Use either epoxy primer or flat wall enamel for the first coat. The top coat can be epoxy enamel or quick dry enamel.
The PHBYC can train volunteers on how to build the boats, so that the volunteers can then assist neighbors in building more boats for their community. Write firstname.lastname@example.org for more information.