Blue hole. 17b-0024

Hi all. I just bought a fixer upper. Got it for $100.
I have a ton of experience fixing the mono hill boats of all kinds. Have worked with west system and fibreglass gelcote etc.
I have read the forum and see some information but need to know more before I start the repairs that I need to do. It has a large crack, fully Broken, from the top down about a foot on the starboard side halfway from the bow and has some other small areas that need some tlc since it was beached on more than a sand beach if you know what I mean lol.
In any case I am trying to learn what the base is so I can use the correct resins.
I am thinking of using west system standard. 105 but have seen the writings of the other west product and would like to know if either would be suitable for this canoe material? I was going to use kevlar,

On the The top rim on the port side is wood and has a large crack as well. What kind of wood is this and what is the best way to fix it? I can get some wood and cut it the same way and steam bend it if necessary.

All comments are appreciated

The hull is made of Royalex. Royalex is/was a multi-laminate, thermo-formed material and its manufacture was discontinued several years ago. The structural component of Royalex is ABS (acrylonitrile butadiene styrene) with a layer of vinyl bonded to the ABS on the inside and outside of the hull. The ABS component has a thin, solid inner and outer lamina, with a “foam core” between them. When the formed Royalex sheet was heated to a specific temperature for a specific time in a large oven, the inner ABS component expanded to produce the foam core. The added thickness that the core provides adds rigidity and allows the overall density of the material to be less than that of water, so Royalex boats typically do not require any flotation tanks to assure positive buoyancy.

I would strongly advise you not to use a conventional epoxy like West Systems 105 resin + hardener. In years past, conventional epoxies were often used for repair of Royalex boats. Some were durable but I have seen other such repairs flake off years later in one big piece. The bond strength, especially to shear stress, of conventional epoxy to ABS/vinyl is not that good.

Fortunately, there is now a much better alternative, G Flex epoxy, which is also made by West Systems. It is more expensive but is far and away the best choice for doing fabric repairs on Royalex boats. It can be mixed one to one, resin to hardener, by eye without the need for metering pumps and can be mixed up in very small batches if needed. It also bonds very well to wood, and I almost always now use it for repair of wood deck plates, seat frames, gunwales, yokes, and thwarts rather than waterproof wood glue,

When bonding G Flex to Royalex, it is preferable when feasible to first remove the outer vinyl layer to allow bonding directly to the ABS rather than the vinyl, although G Flex will bond to vinyl well. Bonding directly to the ABS eliminates the chance of the vinyl layer later delaminating from the ABS substrate taking the repair along with it. On relatively flat surfaces, the vinyl can often be removed by carefully shaving it off with a sharp wood chisel. You can also remove it by sanding, but it takes a good bit of elbow grease. The bond strength of G Flex to ABS is enhanced if you pretreat the surface of the ABS before the first application of epoxy by oxidizing the surface just before epoxy application. Flame oxidation can be done using an inexpensive propane torch that you can buy at any hardware store and there are detailed instructions on how to do this in the instructions that come with G Flex, which are also posted on the West Systems website. If you flame oxidize you must be very careful around any areas of exposed foam core, as the material can easily be overheated causing deformation or melting.

For wetting out and bonding fabrics you want to use unthickened G Flex epoxy. The viscosity of the mixed epoxy will vary with ambient temperature, but it will definitely be more viscous than 105/205-206 or similar epoxies. You can warm the hull surface and the mixed epoxy a bit with a heat gun or hair drier to reduce viscosity if you need to. Because of the viscosity of G Flex, I would not try to wet out multiple layers of fabric at one time. For a mulit-laminate repair, apply one layer. Another layer can be applied over the first while the epoxy on the first layer is still green. I would also recommend using simple weave fabrics no heavier than 5 or 6 ounces per square yard to ensure that the fabric gets thoroughly wet out.

For bonding cracks, I would thicken the epoxy a bit by adding colloidal silica powder (cab-o-sil). First bevel the crack edges to about 45 degrees by guttering out the cracks from each side. You can back up the crack on one side using clear plastic packing tape to contain the epoxy and keep the hull edges in alignment. You can also splint the hull at the broken gunwale if need be with some scrap wood and spring or c clamps. Fill in the cracks from one side at a time and you will probably require multiple applications of epoxy to completely fill the cracks, because the resin will settle slowly down into the interstices of the foam core. Overfill the cracks if necessary because you can easily sand the epoxy fair and flush once it is cured.

Once you have the cracks glued together on the inside and out and the surface sanded smooth, you can lay on your cloth. An aramid fabric like Kevlar is great for the interior. I would not recommend it for exterior repairs. Aramid fibers are actually not very strong in compression, and on the exterior portion of the hull, impacts to the exterior of the hull will result in compressive forces being applied to the hulls external surface. Also, aramid fibers tend to “fuzz up” when abraded. This makes aramid much harder to feather smooth at the edges of patches, and the patch will be prone to get fuzzy if the area is subjected to abrasion in use. I would use 6 ounce per square yard plain weave fiberglass. Common E fiberglass is OK but S fiberglass is significantly stronger and more abrasion resistant.

By the “top rim on the port side is wood” I assume you are talking about the gunwale. If you have a clean crack through either the inwale or the outwale, you may be able to simply glue it back together using G Flex. If the gunwale is more extensively damaged or wood is missing, you can repair either the inwale, the outwale, or both with a splicing segment. The wood is almost certainly ash. You can buy a splicing segment of ash like this if your outwales are radiused:

These segments are usually a bit oversized relative to most gunwales so you can sand them down to match. You can splice in a segment to replace a portion of inwale or outwale using simple scarf joints at either end of the segment. This pdf file on wood gunwale replacement from Mad River Canoe has a section describing gunwale repair using splicing segments that might help:

Thank you so much for the response. I will post back my results in efforts to help anyone else. :slight_smile: