- Tue Jan 21, 2020 10:55 pm
I recently bought a blue Cobra Navigator that had 2 5" long cracks with holes along both sides of the front of the seat area. I got it to see if I could repair it. Spoiler alert repair successful! The cracks as seen below were on either side and looked like the previous owner attempted a botched repair using a 5 gal bucket and a soldering iron. I worked in plastics for a few years and have a decent base knowlege of their properties. I repaired the cracks with a torch and filling/layering feedstock of HDPE I got from plastic cups. The problem IMO with the soldering iron method is that often only one surface heats up sufficiently to bond material. Both need to melt to properly bond. The issue with repairs in general are that plastic thermo sets. This means it becoms very brittle. Same as metal needs to be annealed after quenching plastic is annealed after thermoforming in factories. We can't really do this process for plastic at home. So to combat flexing in an area with brittle welds I layered plastic welds thickly and then formed some strips of 1/8" aluminum to match the contours and riveted them above and below the weld. That way they recieve the majority of the stress instead of the weld. I also added a piece of bike inner tube between the aluminum and the yak as a seal. If anyone wants the Yak it's for sale will be in the classified section. $300 but I'm flexible.
Oh and HDPE that they make these dang things out of is a low surface energy plastic and can't be glued to with any product. If they made them out of ABS or another plastic we could glue and solvent weld them and repairs would actually be simple and effective... but they don't so here we are.
I repaired my prowler 15 over a year ago and it's still holding up great.