Punctures, Leaks, & Repairs

If you’re paddling an ultra-lightweight inflatable in any but the most ideal conditions, it’s almost inevitable that your packraft will develop a leak at some point. Fortunately, that is not a big problem, because small leaks and even large tears are easy to repair.

Contrary to common sense, a leaky packraft is nothing to be afraid of. The volume of air inside the tubes is large, and holes in the fabric are typically small, so it takes a long time to lose so much air you can’t stay afloat. With your Boston valve or top-up valve positioned correctly, you can even top up the air pressure with a few breaths while you are out on the water, and even with a 1 cm (~1/2 inch) puncture in your packraft, air escapes slowly enough that you can paddle to shore long before losing buoyancy. I have paddled around a lake for an hour with two people in my packraft while it was leaking air from a small hole because I was too lazy to fix it before going out… my passenger didn’t even notice.

Because air pressure is distributed evenly inside a packraft and it is inflated to a relatively low pressure, the fabric tends to deform around the objects it impacts instead of ripping open, making lightweight fabrics much more puncture-resistant than intuition would suggest. Punctures are only likely to occur in moving-water situations where momentum shoves you and your packraft against a sharp object with a great deal of force. Aside from avoiding sharp objects, the best way to prevent this sort of puncture is to use an inflatable seat, add padding under your heels, and store hard gear on the deck instead of on the floor. This allows the fabric to bounce, stretch, fold, and flow around obstacles instead of being pinched between a rock and a hard place.

When you are a long distance from shore, such as island-hopping or crossing a fjord or large lake, there are no sharp objects nearby and you are moving relatively slowly, so there is no need to worry about puncturing your packraft there unless you stop to practise juggling knives or do something equally foolish.

With all of that said, it is a good idea to keep your packraft airtight, if for no other reason than it will feel more rigid and responsive on the water when fully inflated. So how do you fix a leak?

Fixing Leaks

The first step is to figure out where the leak is. Large punctures will be easy to find, but most leaks are small and can take more effort to locate. Much like fixing a punctured bicycle tube, the easiest way to find the hole is to inflate the packraft and squeeze it with your hands while rotating it around your head as you listen for the hiss of escaping air. If the environment is too loud or the leak is so small that you can’t hear it, spread some soapy water over the fabric and soap bubbles will form wherever air is escaping. In the field, if you don’t have any camp soap, you can use plain water – soap just makes the bubbles more obvious. Once you have located the leak, rinse off the soap and wipe the fabric dry.

DIY Packraft
Soap + water applied to the packraft to locate a leak – bubbles form where air escapes.

For field repairs, the best patch material I have found is adhesive tape designed for permanently sealing insulation vapour barrier plastic sheeting in building construction. This tape is made of strong plastic film with a very sticky waterproof adhesive on one side. It bonds very well to TPU coated fabric, but can be peeled off without leaving much or any residue. It is available in building supply stores, but it is sold under different names in different countries – here in Canada, Tuck Tape is common; in the USA, you will find Tyvek Tape at any Lowes or Home Depot; in Finland, Kerabit Air/Vapour Barrier Tape is available; and so on. The outdoor repair tape available in the DIY Packraft shop is made by Tuck Tape and is a clear, colorless version that can be applied at temperatures down to -10 degrees C.

If you are unsure what kind of tape to purchase, leave a comment below and I will help you find the right tape in your country; alternatively, if you know what brands of vapour barrier tape are sold in your country, leave a comment below to help others find it. Note: avoid using duct tape – the adhesive is not waterproof.

In the field, simply slap a piece of insulation tape over the hole in your packraft, reinflate it, and carry on. This tape works so well you can keep paddling for months without a “permanent” fix.

Back at home, peel off the tape, make sure the fabric is clean and dry, and plug in your heat-sealing iron. Cut a piece of your heat sealable fabric large enough to cover the hole with at least 1 cm (~1/2 inch) overlap, and round off the corners with scissors. If you’ve built your packraft with the TPU on the outside of the tubes, simply place the patch over the hole, place a piece of parchment paper over the patch, and seal it in place with your iron (being careful not to apply so much heat you activate the TPU on the other side of the tube).

If you’ve built your packraft with the TPU on the inside, you may need to enlarge the hole before rolling up the patch and sliding it inside the tube and then sealing it in place from the outside. Alternatively, you can pass the patch through the inflation valve into your partially inflated packraft and manipulate it into place (this is not too difficult if you backlight your packraft with a lamp or the sun so you can see the patch through the fabric). Seal the patch in place with your iron, being careful not to iron past the edge of the patch.

If you have a leak where multiple pieces of fabric join together and there is no way to form a TPU-to-TPU bond around the hole, you may have to affix your patch with glue such as AquaSeal.

4 thoughts on “Punctures, Leaks, & Repairs

  1. Hi Matt,

    Thanks for great pages! I might try to build a packraft. I have not worked with TPU before so here is one theoretial question about repairs…

    (“If you have a leak where multiple pieces of fabric join together and there is no way to form a TPU to TPU bond around the hole, you may have to affix your patch with glue such as Aqua Seal.”)

    Let’s think I have situation as described above. Would it be possible to bond TPU film (for example link below) on non-TPU outer side and put patch over it? Or would TPU film be useful for something else?

    http://www.extremtextil.de/catalog/TPU-film-clear-transparent-0-3mm-thick-340g-sqm::2804.html?language=en

    1. Hi Tom,

      I have not found a good use for TPU film without a fabric backing… I have tried bonding TPU film to fabric and it does not form a strong bond, so in that situation you would still have to use some glue.

      Cheers,

      Matt

  2. If a leak is from a seam that wasn’t completely sealed in the construction process can you just heat it up and seal it again with your heat sealing iron, or is there a reason to go automatically to using AquaSeal?

    1. Hi Quincy,

      Yep, heat sealing should always be the first choice. If you accidentally sealed a fold into the seam, or if there’s some other reason why you can’t iron it airtight (like if it’s in a spot where you can’t get a complete TPU-to-TPU bond around the leak), then would I use Aquaseal.

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