Post by idea on May 16, 2021 14:35:55 GMT -5
This is to share the build for home design 13ft canoe/pirogue, lightweight - 19.5kg final weight.
Beam - 800mm
Depth at midship - 350mm
Depth at bow - 500mm
Length - 3950mm
Rocker - 80mm
Designed to be used with an outrigger for fishing with an electric outboard (johnson weedless 3Hp bottom end, ebay 2kW electric motor).
This was a variation on stich and glue, using Mycel 1/8in thick rigid foam core to make the hull template and then overlaying fabric. Hull width and depth were chosen to match the 50in fabric width to minimise the fabric waste.
The laminate schedule was;
inside - x2 innegra / carbon - 170gsm, 0/90deg
core - 1/8in Mycel polyurethane foam
outside - x1 innegra / carbon - 170gms, 0deg
outside - 80gsm unidirectional carbon tow, 45deg
outside - 170gsm innegra / carbon - 170gsm, 90deg
outside (bottom) - x1 kevlar - 170gsm
More build photos here - canoe gallery
The foam core was cut by templating with a CNC router to mark the pieces then glued after placing in the wooden frame work form. Glued using polyurethane adhesive and then a wide filet of microsphere filled epoxy added to the inside joints.
The fabric was laid up inside this mold and once cured, the outside chines were carved to give nice bilge and bow radii. The gunnel edge foam was cut back by 50mm and added strips of the hybrid fabric to bring the thickness back up; for a strong edge for the gunnels. And avoid crushing the foam when clamping the gunnels.
I added the diagonal tows to make up for the 0-90 layers of fabric, I was going to use the tow to make up the edge, but it was not enough, so this was a better use for it.
The layer of kevlar on the bottom is sacrificial. After the last layer on the outside I applied some compaction pressure using stretchy bagging film (no vacuum) by pulling and clamping at the edge. This worked to a certain extent and the very slow (60min working time) thin epoxy meant that alot of excess drained out of the fabric.
I ended up using double the calculated epoxy volume at 3gal, due to not bagging the laminate. With an infusion system this design could be very light.
Gunnels are bald cypress, cut from a plank, and held in place with counter sunk screws and stainless rivnuts. I welded up brackets for the ends from stainless steel which give a good strong point for tying down and as a tow point.
Overall i am pleased with this build, being the first time laminating at this scale. The very slow epoxy really helped give flexibility when having to work out on the fly how the fabric panels should be be cut when it was clear my initial plan was not the best idea (full size pieces).
After testing, the plan for the seats has changed, and they will be much lower than in the picture at the top to allow the boat to be used without the outrigger. Inside will then be painted to protect the epoxy from the UV.
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