What are sponsons?
Sponsons are the air tubes inside the kayak skin. They are made from urethane and the seams are RF welded. Urethane is an extremely tough, yet light material. The sponsons slide through chambers sewn to the inside of the kayak skin, on each side. Sponsons provide stability, and also tension to the skin.
Pre-caution: If the kayak is not being paddled, but is in the sun during the heat of the day, release some of the air from the sponsons. Air in the sponsons will expand and could potentially rupture the sponson.
Repairing and / or replacing sponsons.
The sponsons can be repaired or replaced, by removing the sponson from the chamber inside the skin. Turn the skin inside out. The sponson chamber is open at either end, and the sponsons are simply tied into place. Untie the sponson, and attach a long piece of string or rope to each end of the sponson. Remove one side of the sponson by pulling it through the center opening of the chamber, where you access the sponson hose, pulling your rope through the chamber. Repeat with the other side.
To patch a sponson: Use Aquaseal (a urethane adhesive) along with the accelerant, Cotol to shorten the cure/dry time. Follow the mixing instructions on the package. The Aquaseal adhesive is very slippery. Apply weight to the area being patched, ie: bag of sand, rock, book, to hold the area while curing. When it is time to replace the sponson, pull the sponson back through the chamber with the rope that has been fed through the sponson chamber. Inflate the sponson slightly to be sure the sponson lies flat and has not twisted. Re-tie the ends of the sponson to the chamber with a piece of string or rope. This will limit the chances of the sponson shifting within the chamber.
If the sponson valve has broken, replacement valves are available. Cut the old valve off. The adhesive to re-attach is the same AquaSeal and Cotol. Because the adhesive is quite slippery, when you have the new valve in place, use masking tape to hold the valve while the adhesive cures.
If you leave your kayak sitting in the sun, always release air from the sponson. The heat will cause the air to expand and could possibly rupture the sponson.
At one time, the sponsons were made from an opaque unsupported urethane. These could be very susceptible to over expanding. Since early 2000, we have been using a supported urethane fabric which has proven to be much stronger and very robust, and less likely to rupture.
But don’t take the chance!