Build a Fishing Canoe

First sit back and watch the full process so you can get an idea :)

Boatbuilding is a skill that needs a lot of practice and experience, but with this video and the following how-to steps, you might actually be able to build your own! ⛵️

Let's see!

For this boat, we took an example and measurement of an existing traditional fishing canoe and made designs for moulds to fabricate the required parts.

Although we could design very differently (potentially more efficiently) with plastic, we decided to stick as much as possible to the original design, as this enables boatbuilders to use their traditional building approach and helps to teach and maintain their boatbuilding heritage.

For efficient use of materials, our moulds were designed with multi-use in mind (so the L-shape rib can be used as an L-shape bracket to reinforce different parts in a bigger dhow, or a “Muli” mould was long enough to serve for the canoe as well as the slightly bigger Taxi dhow). Note, that this also resulted in heavier parts than necessarily required.

The custom moulds were designed in CAD and the drawings (you can find them in the download files) were sent to the be plasma cut out of 4mm steel sheets.

The sides of the moulds were designed with alignment steps, to make assembly easier (due to an unclean cutting of the plasma cutter this resulted in a lot of manual post-processing work and unclean edges though).

The rest was fabricated in-house: Assembling, bending, welding, drilling and bolting. To avoid swelling of the mould under pressure, reinforcement brackets were added to the sides.

NOTE: For future welding jobs, we would cut the sides of the metal parts straight (without alignment steps), unless we are 100% sure about the quality of the cutting. This simplifies the process and even allows us to fabricate completely in-house, making the process more affordable at the same time.

To extrude / inject into these parts you will need quite a fast and powerful Extruder, as they have quite a big volume. We are using an industrial extruder, but an Extruder Pro ([filtered] Design) could also work (to be tested!).

With our extruder, we filled the parts in about 10-15min with 15-20kg of plastic. As we noticed a lot of shrinkage and air pockets in the material, we adjusted the process and continued injecting plastic for 1-2 more minutes once the plastic came out the relief holes (indicating that the mould was full) to achieve more compression.

We used 100% HDPE for our parts.

LEARNING: Make sure to check the quality of your parts to know if you need to adjust anything in the process. The weight is a good indication for the likeliness of airpocket inside.

Time to prepare all your materials and tools for boat building. This is what you'll need:

Plastic material:

• Custom parts for the L-ribs, V-rib and front/back "muli"
• Lumber for the base, hull and interior (ideally min. 3m long) You don't have to choose exactly the same sizes - have a look what you have available that can be strong enough

Fixings: screws and bolts, corking cotton

Tools:

• standard working tools: saws, chisels, drill, screwdrivers, ruler, square
• traditional dhow/boat making tools (see image)
• heat gun (or welding gun) / melting machine

Space: Use a flat space with smooth floor to make it easy to collect the plastic dust / particles.

First very important step is to level your keel ("Utako") as all your next steps will be based and relying this straightness and level.

Material used:

• Keel Plank (9x2", 16ft long)
• Base logs (5x5")

Levelling tools: Spirit Level and Hose pipe

Process:

• divide the keel length into 5 and put a log at every fifth
• place the keel and make sure all is level
• fix the keel to the base with nails (or pegs) on both sides
• mark the center line on your keel, to align all coming parts to your center

Note: Plastic planks can sometimes have a bend or twist. You can help bring them on one level by adding weight.

Materials used: Mulis (2x) and temporary supporting poles ("Mabunda")

Process:

• mark the center line on the front and back side of your muli
• if your muli is a bit warped, shape it on both long sides, so that its straight and symmetric
• cut a ribbet according to the size of your planks
• choose the angles for your Mulis to sit on the keel (we chose 45° in the front, and 70° in the back)
• cut the base of your muli according to the needed angle
• mark the shape of the Mulis on your keel and chisel it out (about 1/2" deep) and join them
• support the Mulis by adding Mabundas on the sides and the end
• use your Kabiru (plumb bob) to ensure your Mulis are straight and aligned to the center
• to fix the mulis in place, drill a hole through Muli and keel and join with a nut an bolt

Note: We used silicone between the surfaces and cotton around the bolt to seal the joint.

The Bitana is a bracket reinforcement to hold the Muli to the Keel.

Materials:

• L-shape rib pieces (2x)

Process:

• shape the Rib piece to fit the angle of the Muli to the keel
• make it tapered so the planks can go alongside
• drill and bolt it to the Muli and the Keel

Do this on the front and the back side.

You can choose different widths depending on how you want to use the boat. To be able to transport people comfortably, we chose the width to be a quarter of the length. It helps to choose the width according to the planks you have available.

Materials:

• "Mapande" (wooden poles)
• thin and long easily bending piece of wood/plastic for temporary "kinara" (top plank of the hull)

Process:

• attach Mapande at the widest point of the dhow
• create the rough shape with thin planks
• use a rope (or ruler/tape measure) to confirm equal width between both sides
• put rest of Mapande in place on the remaining base beams
• fixate your temporary "kinara" on the Mapande to keep the shape
• secure the position with "Mitindikani" - horizontal poles to keep the distance

Materials:

• L-shape ribs (14x)

Process:

• place your ribs in place (in pairs) with equal distances to each other (we chose a distance of 12" between the pairs)
• if the parts vary in weight, make sure you distribute them so the weight is balanced (front/back, left/right)
• now cut the longer pieces according to the shape
• use a square to make sure the ribs sit in a right angle to the keel
• if there is warping/uneven sides of your pieces, use a shoka or saw to make them sit alongside nicely
• bolt the ribs to the keel
• place mitindikani (crossing poles) to keep the ribs in place

Materials

• V-shape ribs "Farkumu" (2x)

• The V-shape beam sits on the Bitana. To join them, make a lap joint between Bitana and Farkumu.

• Join them with a bolt through the keel

THIS STEP TAKES A LOT OF TIME TO MAKE THE HULL FIT WELL.

Material: 9x1,5" x 10pcs

Start with Kinara (top plank)

• mark and cut the bevel according to Muli
• place plank in place and clamp it (we use our local technique "kisongo")
• if necessary, adjust the ribs, so they are aligned nicely
• fix in place with screws
• take the second piece, repeat fitting and cut a Z-joint to join the pieces Do this on both sides, so the Kinara is all around the top.

Materials: 9x1.5" planks (6pcs)

• finish the other rows with the same process
• in contrast to top plank (kinara), you can use a bevel joint between the planks instead of Z-joint -alternate the position of your joints as otherwise it creates a week point where all the joints are

MAKE SURE ALL PLANKS ARE FITTED TIGHTLY, SO THERE IS AS LITTLE GAP AS POSSIBLE. (you can use a saw in between to cut of uneven corners)

Next step is to lock everything well in place with side strips and crossing beams

Material:

• Tampisi: 2x3" planks (4pcs)
• Fundo la mongoti (crossing beam for the mast): 9x2"
• Fundo la nyuma (back crossing beam): 9x1.5"

Process:

• we cut a step into the ribs to make the tampisi and firari sit flush on the sides
• place the tampisi onto the step and fix in place with screws
• place a the "fundo la mongoti" on top of the tampisi at 1/3 of the keel from the front
• place "fundo la nyuma" on top of the tampisi in the back (where desired)
• make lap joints between Tampisi + Fundos and bolt them together

Staha is to reinforce the Muli to Kinara (and to provide sitting area and storage)

Used materials:

• 9x1,5" plank
• 2x4" plank

Process: FRONT STAHA

• cut the top of the muli so its extending the line of the top plank
• place a 2x4" beam to support in a right angle to the center line as support
• cut planks to cover the front triangle of the boat

BACK STAHA

• we simply fitted 2 planks to make a sitting base (and left a hole as it can be useful to fix ropes etc.)

Firari and Dufani are the top to finish off the top edges and reinforce the structure once more.

Materials: Dufani (5x1", 4pcs), Firari (2.5x1", 4pcs)

Process Firari:

• position the Firari at the top of the mataruma (and shave them so the Dufani can sit levelled)
• try to keep the distance between tampisi and firari parallel
• join the planks with a bevel joint and screw them in place

Process Dufani:

• start by cutting the angle in the front so it attaches well into the front/back corner
• for bending the plank, go "pole pole" (slowly slowly): clamp the first foot (30cm) and screw it in place, then bend the plank, screw the next foot, etc. until it is completely bent
• do the same from the other end and meet in the center with a bevel joint

Time to turn your dhow upside down to finish the base!

Important! Don't forget to create a water channel on both sides for the water to pass through. (see photo)

Cut your planks according to the shape of your base, and make sure to fit them with as little as gap as possible.

Screw them onto the ribs. Base is done :)

Now last step remaining is to finish and seal the dhow, so no water can enter inside.

• shave the excess corners of the planks to smoothen the surface of the hull
• we used the traditional corking with cotton and hit it inbetween the gaps of the planks with the "chembeo"
• to finalise, we topped up the kalafati with melted plastic with a heat gun to seal it completely (it's like plastic welding)
• with the plastic welding we also sealed the screws and other gaps

NOTE: The plastic welding was done very low-tech and is to be tested! We hope to test a proper plastic welding tool soon for the sealing of the hull and will share the results :)

Big moment! When you're done with the hull and first round of sealing, it's time to test:

• turn the boat around
• launch it in the water (or fill it with water)
• observe where the water is passing through gaps to find any leakage
• finalise the sealing on those points

Alright, you're basically done!

You can now decide how you want to power your boat: With a motor, paddles, or a sail?

We are sailors, so we obviously put a sail, with a rudder. (The mast and boom are traditional ones out of wood) Additional bonus if you use a sail: Make it an eye catcher and use the opportunity to create awareness ✨

Now go out there, inspire others, tell them the story (and to join the fight against plastic pollution), and enjoy!

If you get to this point or it inspires you to do something similar, please let us know, we'd be so happy (you can tag us on social media with @​​​​​​​theflipflopi)

Oh, and always have something with you to bale out water - even if no water is coming in from the bottom, it might be coming in with the waves :)