In the last step, we joined the tube pieces to the floor, and in this step we’re going to join the tube pieces to each other.
Our first task is to cut narrow strips of heat-sealable fabric that will form the seams between the tube pieces. Your kit will include one or two pieces of fabric large enough to cut these strips from (if you ordered extra fabric, the seam fabric may be added on to that piece, so check the length). Avoid cutting the strips much longer than necessary, as that will waste fabric that could be used for other things.
Here are the lengths of 2 cm (0.8 inch) wide strips of heat-sealable fabric required for bonding tube pieces together (includes at least 5 cm/2″ extra length):
- Seam between pieces #1 & 2: 90 cm (35.5″) (two required)
- Seam between pieces #2 & 3: 95 cm (37.5″) (two required)
- Seam between pieces #3 & 4: 95 cm (37.5″) (two required)
- Seam between pieces #4 & 5: 100 cm (39.5″) (two required)
- Front center seam* (between pieces 1-Left & 1-Right): 110 cm (43.5″)
- Rear center seam* (between pieces 5-Left & 5-Right): 60 cm (23.5″) + 115 cm (45″) to meet at pointed tip, or a single 175 cm (69″) piece
*Do not seal the front and rear center seams yet.
These narrow strips of fabric should be 2-2.5 cm wide – any wider than that and you may have trouble avoiding wrinkles in your seams. For the demo packraft, I cut strips 22.5 mm wide. This width provides enough overlap for a very strong seam, without being so wide that wrinkles will form as the fabric is curved in multiple directions.
When your narrow strips are ready, lay out your packraft with the TPU (shiny) side of the floor facing up (TPU side of the tube pieces facing down). Fold the end of one of your narrow strips so a 1 cm tab is created, with the TPU on the outside of the fold.
Center the folded end of the strip between the tube pieces and the floor, with the fold halfway between the outer edge of the floor piece and the corners of the tube pieces. The TPU side of the long strip should be facing up, touching the TPU side of the tube pieces, and the 1 cm fold should be facing down, in contact with the floor piece.
Use your heat-sealing iron to bond the tube pieces to the end of the strip and to the floor around it. Remember to apply pressure to create a good bond. Then flip the packraft over to seal the 1 cm fold to the floor. We will come back to this area later, so don’t worry about the small pocket that has formed at the corner of the floor.
Now that the narrow strip is on top of the tube pieces, cover a bowl in parchment paper and place it under the fabric so you have a raised, curved surface to seal over. This will help you create a wrinkle-free seam. Hold the tube pieces together and bond the strip to them with your iron, being careful to keep the strip centered over the seam as you work your way along, a few cm at a time.
Check the Tips & Tricks topic in the Forum if you are having trouble holding the fabric in place as you work.
Important: as you work your way along the seam, keep the finished portion hanging as straight as possible away from you (aligned with the part you are sealing) to prevent biasing the curve towards one side of the seam. If you allow the sealed part of the seam to curl consistently to one side, the corners of the tube pieces will not line up properly when your reach the end of the seam even though the sides are the same length. Watch this video for an explanation:
Note: Some people prefer to tape the seam first before heat sealing it. This takes longer, but allows them to make sure everything is lined up correctly before a permanent seal is made, and may make possible to seal the seam on a flat surface.
When you’re nearing the end, leave the last few cm unsealed, as we will finish the end in a later step. For now, you can flip everything over and run your iron over the seam from the other side, just to make sure you’ve got a good seal.
When that’s done, you can seal the other seams following the same procedure, but leave the front and back center seams unsealed for now.
Questions? Please post a comment below.