I purchased an Old Town Discovery 169 that had spot where the polyethylene had cracked and was repaired with an unknown filling material. The material was no longer sealing the hole, which allowed water to get in and delaminate the polyethylene. I have removed the patch material and area of separated coating, but am not sure what to use to fill in the area prior to installing a skid plate to cover and protect the whole area. Any suggestions on what I could use that is both effective and somewhat inexpensive? Has anyone used or heard of Gemini Patch N Protect (http://geminimaterials.com/patch-n-protect)?
no never heard of it. But how did the canoe crack? Was the canoe handled poorly or stored out in the snow during winter? Reason why I’m asking is because if it hull is in bad condition and degrading, it may not be worth fixing. Any idea how old it is?
It happens This is a so-called “triple dump” polyethylene boat with solid strata of poly on the inside and outside, and foam poly at the core. If one of the solid layers is breached, the adjacent solid poly can and will progressively separate from the foam core.
I have heard of a variety of filling agents used on Royalex canoes eroded into the foam, but that material is ABS, a plastic to which a variety of adhesives solidly bond much more easily than polyethylene.
I have done repairs of this type on Discovery canoes using G Flex epoxy made by West Systems. I don’t know if you will consider it relatively inexpensive, but if the area you need to repair is not too expensive you can probably fill and cover the exposed foam core with one kit like this:
In addition to 4 oz of resin and 4 oz of hardener, this kit contains colloidal silica powder which you can use to thicken the epoxy, mixing/application spatulas and mixing cups. You will also need an inexpensive propane torch which you can acquire at the hardware store if necessary as well as some denatured alcohol, sandpaper, and masking tape.
Make sure you remove any solid poly that has already separated. It sounds as if you have done this. Bevel the edges of the solid poly where it remains attached. Wash out the foam core with dilute soapy water and a scrub brush unless it is very clean, then rinse well. Clean area with alcohol and get the foam core as dry as possible.
In order to achieve a bond you will need to pretreat the poly by passing the tip of a propane torch flame over the hull surface. The directions that come with the G Flex instruct you how to do this in some detail. You may want to mask around your repair area with tape to keep things neat.
You can then mix up small batches of epoxy and stir in silica powder to thicken it to a mayonnaise consistency. Apply this to the foam core and allow it to settle in. Wafting a heat gun or hair drier over the applied epoxy will reduce its viscosity and allow it to permeate the open cells of the foam better.
You will likely need to make multiple applications of thickened epoxy to fill in the void and reconstruct the missing outer layer of solid poly. The thickened epoxy can be used much like wood putty by slightly overfilling the defect, then sanding it fair and flush with the adjacent hull. If you are not going to apply an abrasion plate, spray paint the repair to protect the epoxy from UV exposure.
You can also use G Flex and fiberglass cloth to make better abrasion plates more cheaply than you can by buying a commercial kit but that might be a subject for another thread.