Setting Up the Construction Jig
Boatbuilder Greg Rössel and host Rich Hilsinger join forces to explain the steps involved in correctly and accurately setting up station molds—regardless of whether you are building right-side-up or upside-down. This is the big moment in which the abstract two-dimensional world of lofting turns into three dimensions. And this is where, if a bit of care has been taken, thoroughness in lofting begins to pay big dividends.
To build a hull upside down, we begin with a ladder-frame strongback on which we set up the molds. We then proceed to lay down the construction grid—the centerline and the station locations. Starting with the ’midship mold and working toward each end, we align the molds to their index marks, and then plumb, square, brace, and fasten them. Before setting the backbone in place, we install the transom jig that was drawn on the lofting board. We then check our work by wrapping a light batten around the setup from the stem rabbet to the transom.
To build right-side up, we first set up the keel on a decent foundation, so its position matches that on the lofting. As we did with the upside-down method, we then establish the centerline, lay out the station spacing, and erect the molds so they are plumb. Once we have all the molds fastened and braced in place, we’ll check the setup for fairness.