The building jig for the scow consists of the following parts:

• Two longitudinals of 73x46 (3"x2") softwood. These two parts are important for alignment of the parts of the boat, so try to select really straight stock to save yourself work. If straight wood is not available, you will need to strike a chalk line along the longitudinals and align everything to the chalk mark.
  
• Two transverses of 46x46 (2"x2") softwood. These are bolted to the longitudinals by 150 (6") coachbolts at positions that are not very critical.
  
• Various uprights, to support bulkheads, of 46x22 (2"x1") softwood. These are screwed to the longitudinals.

You might want to cross-brace the longitudinals to each other to stop the jig from 'lozenging' when you turn it over.

There are various little 'tweaks' that should/can be made:

• Add some little patches of ply to the four centre uprights to support the mid seat/tank bulkheads at the right height.
  
• You might want to use some temporary ply brackets to hold the bow and stern transoms in place until the sides are joined to them.
  
• The ends of the two transverses support the side panels while they are being fitted. The top of the transverses will need to be cut away until they are 81mm below the top of the longitudinals if you are using exact-cut side panels, or by more if you have left some excess material on the top of the side panels to trim off later (as I recommend).

Use only mechanical fastenings (screws, bolts, etc) to assemble the jig, and in particular no glue, so that it can be dismantled inside the boat without damaging it.