Constructing a Jig

The plan sheet for a jig or strongback only came with the kit plans. It wasn't immediately clear to me what lengths and sizes of timber I should buy so I had to sit down and decipher. I also happened to get to this stage right at the nationwide timber shortage, haha. Several trips to Bunnings, the biggest hardware store chain, proved to be futile since the shelves were empty. I was also cautioned against buying timber from Bunnings due to its supposed inferior quality i.e. difficult to find relatively straight long sections of timber. So I sourced a more local timber supplier, Naturewood in Capalaba and drove there to place the order face to face, equipped with a spreadsheet of printed out sections and a copy of the jig plan sheet just in case.

I explained to the gentlemen that I'm building a boat and I need timber for the strongback. They looked at me somewhat incredulously until I whipped out my printed sheets. Lucky they had suitable timber sections in stock and were able to deliver them the next day. I ordered 140x45 for the base and 70x35 for the posts. I also bought 75mm screws, metal corner brackets, nails, a cheap sheet of plywood for the gussets and builders wedges.

Then I set to work with a circular saw, first marking and cutting the base timber sections to length and roughly aligning them on the ground. The unevenness of the floor in the shed became painfully obvious and the builders' wedges were really helpful. I used the corner brackets as a temporary way to fix the sections, but I would say that isn't necessary at all. Once I had the base level on the floor, square and all the cross braces fixed in their positions, I installed corner gussets to really fix the base.

Then it was time to cut the post sections which is straightforward as all heights are given on the plan sheet. It's more fiddly to fix them to the base. An extra pair of hands is really helpful at this stage. Since I approached this on my own, I clamped a spirit level to each post while I screwed it to the base so that it was plumb. Later I had to make some corrections as it turned out I was cross-eyed while doing this and some of my posts weren't plumb. Posts needed extra support with cross braces and here I think the jig needs more than what's shown on the plan. For example, there are no cross braces for frames A, D and E and they definitely need extra support. Frame A needs cross braces to prevent side to side movement, and frames D and E benefit from braces to reduce fore & aft movement. The angled posts for frame S will also need extra support. It may not be immediately apparent that they're needed but I think anyone would find out once they start installing stringers that tend to pull the frames out of alignment.

Once I had the jig constructed I had to place it in a final position on the floor. Initially, I placed it too close to the wall and I'm glad I moved it to give myself more space to work around the boat. Of course, because the floor is so uneven I had to re-check levelness and readjust all the wedges and little blocks of plywood and timber to prop it up.