The average adult human can expel a maximum of less than 4 litres of air per breath and a packraft has a volume of over 300 litres, so to inflate a packraft by mouth would take over 75 maximum-capacity breaths (realistically it’s a lot more than that). Trying to inflate a packraft in this way is an unpleasant and time-consuming task that leads to dizziness and tingling fingers – I tried it once and after gave up after half an hour, when my packraft was only partially inflated.
Luckily, there is a lightweight solution to this problem: the inflation bag. The inflation bag allows you to scoop a large volume of air into the bag, twist the top closed, and then squeeze it to force the air through a nozzle into the packraft.
Packraft inflation bag kit parts:
- Small piece of black silicone rubber tubing (roughly 5 cm/2″ long and 7/8″ in diameter)
- Small piece of black 1000D TPU coated nylon fabric, approximately 10 cm (4″) square
- Approximately 2 x 0.5 m of TPU coated 40D ripstop nylon fabric (in the color of your choice)
- Heat sealing iron
- Silicone coated baking paper (i.e. parchment paper – available at your local grocery store)
- Polyurethane glue, such as Aquaseal
- Small wood block or thick book
- Heat-resistant work surface
- Plastic coat hanger (optional)
Putting the pieces together:
Cut the small square of black 1000D fabric into a circle roughly 8-10 cm (3-4″) in diameter:
Find the center of the circle by folding it in half twice. Mark it:
Cut slits in the center of the 1000D circle in a starburst pattern (radiating out from the center), just wide enough so you can slide the short length of black silicone tubing through the 1000D:
Fold the 40D fabric in half and mark a spot near the center of the fold. Then cut a 2-3 cm (1″) hole at the marked spot:
Align the hole in the 40D fabric with the starburst hole in the 1000D circle and heat seal the two together (you may find it easiest to place a wooden block covered in parchment paper under the 1000D circle):
Note: if you heat seal the 1000D for too long you could melt through to the TPU on the far side – practice on a scrap first.)
Fold the 40D fabric in half and align the edges. Heat seal the edges together in a strip 1-2 cm (0.5″) wide. Do the same on the other side to form a sack with three sides closed (one fold and two heat sealed edges):
Optional: Cut two ~15 cm (6″) lengths of plastic rod from a plastic coat hanger or other cheap plastic object. These will make convenient handles for your inflation bag, but are not necessary if you want to save a few grams.
Fold approximately 3-5 cm (1-2″) of the unfinished end of the sack inward around the optional plastic rod and center the plastic rod between the two edges of the sack. Heat seal the fold around the plastic rod or, if you are not adding plastic rods, simply heat seal the fold to provide a finished edge to your inflation bag. Flip the bag over and do the same on the other side.
Roughen one end of the black silicone tube with sandpaper and then coat it with Aquaseal and force it through the starburst hole in the 1000D fabric, just far enough that the triangles of 1000D fabric (formed by the starburst cut) are fully in contact with the silicone tube. Set it aside and allow the glue to cure.
Note: If you prefer to have the TPU-coated side of the fabric facing out (i.e. TPU on the outside of the bag), turn the bag inside out before inserting the silicone tube.
Using the inflation bag:
- Open the two-way (deflation) valve on your packraft’s Boston valve (the larger of the two openings)
- Press the silicone tubing into the valve with a clockwise twisting motion
- Holding the inflation bag by the open end with two hands, scoop air into the bag
- Quickly close the bag and twist the top so air cannot escape
- Squeeze the air-filled bag between your arms and body to force air through the valve into the packraft
- Repeat steps 3-5 until the packraft is fully inflated
- Holding a finger over the inflation bag to prevent air from escaping, remove the inflation bag from the Boston valve by pulling and twisting the black tube counter-clockwise. As the tubing comes out of the valve, quickly place a finger over the valve opening to prevent air from escaping
- Screw the Boston valve closed
- Unscrew the cap on the Boston valve’s one-way valve
- Top up the air pressure in the packraft using your mouth until it is firm
- Screw the cap back on the Boston valve
Note: Inflating your packraft entirely through the one-way check valve is possible, but airflow is somewhat restricted by the check valve, so it takes longer than the above method, even though some air is lost to backflow when using the above method.
Questions? Leave a comment below!