How to build a seakayak /PART 2
second part of our tutorial on how to build a seakayak Bette 500 HV, using plywood and epoxy resin , with the so called “stitch and glue” system
cut the paper templates, mark them on plywood, and join plywood sheets
required tools: pencil, adhesive tape, pencil, knife and spare blades, plastic film
time required:
- templates’ cut : 5 hours
- lofting parts on plywood : 6 hours
- joining plywood panels with bevel joint : 2 hours
cutting the paper templates
it’s a quite tiring operation, but it’s necessary to have the maximum precision in marking and cutting the panels that will make the kayak’s hull.
Basically I unrolled the CAD print ( a 5 m paper roll) on the floor and cut the shapes with a sharp knife, slowly and with a good precision staying on the printed lines; if your garage has a poor light source (as mine) an headlamp may be useful; use always sharp blades
just one more advice: if you have kneepads, use them !
Lofting the parts on plywood sheets
-place the two sheets side by side on the short sides, block them somehow on the ground (anyway, it’s not that easy to move a six square meters panel…)
-start marking shapes from the bottom panels with a pencil , stay as much as you can near tha sheet border, 1cm is fine, and try to avoid too much gap among panels, even here one cm or two as minimum distance is ok,
note: it’is seriously raccomandable to have all the joinings on the same side of the plywood sheets, to reach this result you to mark one hull panel, and turn the template to the other face to mark the other one (panels are coupled since the hull is simmetrical, we have two bottom panels, two knee panels and two side panels)
how to mark: basically take the template, unroll it on the plywood sheets , pay attention that it is carefully unrolled and perfectly leaning on the plywood with no wrinkles , block it with small pieces of adhesive tape (one each 20 cm is fine) going from stern to bow, and mark the shape with a pencil, make some practice till you do a steady dark grey marking, not a thin trembling line
at the end of this stage we have marked the six (5 meters long) hull panels and the two lower small strips of the deck ; we’ll mark other parts on the third plywood sheet and on the clippings of these two
joining plywood sheets
things now start to become sticky !!! litterally….
I choose an easy-to-do bevel joint which consists in a small plywood rectangular patch that joins the two panels , glued with thickened epoxy resin. We have marked the panels so that we’ll do the joint on the same face of plywood sheets and they’ll result inside the kayak hull ;
some tricks:
- we’ll join the sheets only on the marked parts
- taper the sides of rectangular patches so the we can laminate glass fabric over them smootly and easily
- place a large board on the floor, wrap with a thin plastic film (food film is ok) and place plywood joint on it, to avoid gluing plywood sheets on the floor (yes, epoxy adheres perfectly to floors !!!)
- additional trick: place the plastic film wrapped board underneath plywood BEFORE marking the parts
use epoxy resin thickened with silica and cellulose fiber (first mix very well epoxy resin and its hardener, and then add silica, about 1:1 in volume, and then adjust density with cellulose fibers, or at least this is my own recipe… )
press the joints for one minute, then clean the resin that squeezes out of joints, then press the joints agian and keep them pressed for 6-8 hours; to do this you may use anything enough heavy and a small wooden board (as always, wrap the wood in plastic food film to avoid accidental gluing) to keep an even pressure
at the end of this process we have a huge 6 meters long 1,5 wide plywood board
on the next episode we’ll cut the hull panels’ and start to join them to let the kayak’s hull take shape
see you soon !