Professional Tips for Lofting the 3 Most Common Elements
By Morten Olesen © 2012, All Rights Reserved
Building your own boat could be the culmination of a lifelong dream, or an impulsive project if you're the avid woodworker. In either case, the amount of learning that goes into following a boat design and crafting the panels can look daunting.
Lofting, in particular, is a drafting technique that takes a keen eye for shape, a good head for mathematics, and confidence in your woodworking talent. Don't fret… becoming a lofter is easier than you think once you master the 3 most common elements. Plus, learning this new skill will open up a world of design options for your building projects.
Assembling your lofting tools in advance will help you go through the steps with more ease. Most of the materials are common household tools, like a pencil (ink from a pen may soak into the wood grain), measuring tape and carpenter squares. You’ll also want to buy some lumber filler to construct your curves and arcs.
Reading the Boat Plans
Each of your boat plans is based on a set of drawing files. You’ll see top-down and profile perspectives, dimension of the elements like offsets, diagonals and buttock lines; assembly details and more. If you purchased 3D boat plans, you'll also have the added advantage of being able to slice, dice and rotate the plans via computer to see every possible angle.
Curves in panels can be challenging if you're a new lofter, but like all elements of the boat plans, are based in scale numbers. Take a close look at the panel plates; on some boat plans the dimensions are depicted in both U.S. standard and metric units. Be careful not to mix the dimensions as you make your cuts!
Curve panel lofting begins with a grid, drawn with vertical lines using a carpenter’s square. Once you’ve finished marking your grid on the plywood, it will resemble a football field. Set out the dimensions of the panels, marking with a pencil along the long edge of the plywood.
With that done, make the curvature of the panel. One of the most recommended ways is to hammer in small nails at the cross-points, then fit the lumber fillets to the nails. Hold the fillet in place with some extra nails or weights. Repeat the procedure on the other side of the panel, then use your circular or saber saw to cut the curve out of the panel.
You may find lofting symmetrical elements, such as the nesting, easier than the curved panels. A file based on symmetrical pieces will show each piece as part of the overall boat plans. Some symmetrical elements have dimensions set from the centerline, which makes the centerline part of the symmetry line.
A carpenter’s square will be your tool to set the centerline on the plywood. You’ll mark the dimensions on the wood from the horizontal distances. Afterward, you can draw the out-line of the element by connecting the points you marked with straight lines. Finally, you’ll draw the inside of the element, starting with the vertical sideline
Your boat plans will include perpendicular elements that are relatively easy to configure. Create a straight line (12 inches long, for example). Then, with your measuring tape, make a mark approximately perpendicular to your line, in this case about 16 inches from the first line.
From the other end of your first line, mark 20 inches in the direction of the mark you made from the first end of the first line. Mark the distance where it crosses the first mark, and you will have a triangular-looking figure. Where the points cross, the lines are perpendicular.
While you hear a lot of talk about the challenges lofting presents, once you've learned the right way to do it, you'll more quickly and confidently.