My 7-year old Helios has a leak on the starboard side, bottom-back (between rower & stern) at the black-oval patch which is over a seam. Can I repair this?
The material is a sythetic rubber called Nitrylon, similar to Hypalon. For the leak you are describing, and it could be either water or air at that point on the boat, I would use a bead of AquaSeal along the edge of the patch that is leaking.
AquaSeal, by McNett Corp., is a clear urethane adhesive sealant. It has the consistency of caulking and needs to air dry overnight. Clean up the area first with alcohol or acetone, let the solvent dry, then lay out the repair dead flat and place a thin bead of AquaSeal along the suspect edge.
The best way to detect the specific air leak section is to use really soapy water and look for bubbles.
To detect the specifics of a water leak, dry the outside of the kayak and fill the interior with some water. You should be able to see where it leaks out from below.
AquaSeal can be purchased from us, but also most dive shops carry this material.