Now that our runner bodies are finished we wanted to add a carbon fibre skin for added strength and looks. My cousin Les and I have never used carbon fibre before so this was going to be a learning experience (which sometimes looked like a circus). We've started 4 runners to date and each time the process of getting the cloth to adhere everywhere is getting better and better.
For our first few tries we decided to use Mighty Stor Extra Large Vacuum bags. These bags are commercially available and used to compress clothing and bedding for storage or travel. We coated the inside of the bag with furniture wax to release the plastic. The runner is given a thick coat of epoxy. We wrapped the cloth all the way around and used wood slats covered in wax paper to push the cloth up under the bottom edge. More epoxy is brushed on to thoroughly soak the cloth. We slid everything into the bag, sealed it up and used the central vac. to pull as much air out as possible. Since the runners are not perfectly rectilinear the cloth, soaking in epoxy, did not get pushed onto all the surfaces cleanly.
When we upgraded to a proper vacuum pump the results were much better. We could fire up the pump every hour or so to make up for leakage. Since a runner is not a rectangle it was still difficult to deal with the slack cloth created by the trapezoidal shape. Getting the cloth to fully wrap around the bottom edge up to the steel also proved to be a headache.
We decided that this could work better if we ignore the bottom edge and just glass the sides and top. The small lips at the bottom could be epoxied later with some carbon added to make the epoxy black.
In this photo you can just make out that the pivot hole is over-bored and then remade using an epoxy graphite mixture. The hole is reformed around a heavily waxed 3/8 bolt mounted in a custom made jig to hold the bolt in the correct position relative to the top edge of the runner.
The runners still need finer sandpaper and finish work. This one was used once and seemed to run just fine. While using another set the front of the boat went through the ice and hit bottom in 3 feet of water at full throttle! The boat was fine! The steering push rod and steering runner chock were both bent out of shape. The runner itself did not come apart or even bend but suffered a deep gouge on one side, probably where the steering push rod ran into it.
We formed a little dam around the pivot hole and overfilled it. Instead of being left with a concavity after the epoxy sets and shrinks it will be proud and can be sanded level.
