The stitch and glue boat building method will require long planks that most plywood dimensions in length are not meeting. Joining two pieces of ply to form the plank is therefore needed.

Scarf Join

 

The difficulty consists in being able to scarf each mating plank at an angle that would provide enough gluing surface area. The rule is to allow at least 1:8 proportion between ply thickness and scarf length. In my case, I use 6 mm ply and the scarf is 5 cm wide.

scarf join

Care is needed when gluing the two planks in order to maintain alignment. I am drawing a line along the two planks with a pencil before starting to cut the scarf and use that later on when gluing to ensure alignment.

PIC_0069

In my first boat building project I was reluctant to use the scarf join as I considered it too hard for a newbie but it really isn’t. Here is what you need to do:

  1. draw the alignment line
  2. Make sure you allow for length of scarf joint when marking out (5 cm in this case)
  3. align the 2 mating pieces, one on top of the other
  4. use a block plane to cut the scarf. Ensure alignment of the ply lines
  5. use 60 grit sandpaper for finishing
  6. wet the surface areas with epoxy, apply thickened epoxy and fasten tight

TIP: cellophane will not stick to the epoxy after it cures. You can use cellophane to protect table, etc… I used plastic bags in the past but they are too soft and you risk to not be able to remove it in the end. If cellophane is not available use strong, thick plastic bag or similar.

See this short clip on scarf joins

wooden boat stitch and glue selway fisher kingfisher 14

Scarf joints can also be made quite easy with a router, positioning it at the right angle and improvising a sledge to let it move over the cutting surface.

 

Some use a belt sander to avoid the planing but this involves lots of dust!

 

Butt Strap

Joining planks for boat building using the Butt Strap is fast and easy.

butt strap

Attention is needed when gluing the planks as the but will always need to be on the inside of the boat, therefore requiring 2 mating joints (port and starboard)

butt strap

  1. cut out the but strap for each join. 12 cm wide but keep 3 cm away from the edges as you will need this space later for stitching and filleting the seams.
  2. position the 2 planks one next to the other, apply the but strap
  3. wet the surface areas with epoxy, apply thickened epoxy and fasten tight

TIP: cellophane will not stick to the epoxy after it cures. You can use cellophane to protect table, etc… I used plastic bags in the past but they are too soft and you risk to not be able to remove it in the end. if cellophane is not available use strong, thick plastic bag or similar.