Lofting Low

 

Everything should be made as simple as possible.

But not simpler.

Albert Einstein

Lofting Low

Being naturally lazy, I've spent an inordinate amount of mental energy on making boat-building easier. Over the years, whole swathes of the process have been successfully dumbed-down toward small enough bites for Anke and me to chew. Economical in time, space, money and materials.

One such swathe is is the process of lofting a vessel. 

'Lofting' is laying down the lines which define the shape of the vessel and some its components. All the individual lines need to agree with each other, meaning extensive cross-referencing and nudgings until they do. This is a finicky process, involving patience, focus and good spatial visualization.

Generally, this is done full-size or at some large fraction thereof. The resulting vessel is 3D (three-dimensional), but the lofting is generally laid down in 2D... done on a flat expanse called the lofting floor. Often, it was located in a loft under the roof of the building shed... hence the name.

Still with me?

Okay, let's take a survey of things we need:

• A lofting space - This is generally in addition to the construction space and preferably stays available throughout the build. The lofting floor should be out-of-the-way, amply sized, smooth, sheltered and hopefully warm.
  
  
• Esoteric skills - Lofting isn't rocket science, but neither is it run-of-the-mill. We need to understand the specification of points and lines as they relate to the plans, the techniques for laying them down, fairing, correcting and coordinating and further techniques for taking them up again to apply to our growing vessel and its parts.
  
  
• Special tools - The more complex the lofting, the more tools we will need. Splines, ducks, tacks, pencils (of various colors?), spiling (taking the pattern of a curved or otherwise complex shape) plus related tools... and so on.
  
  
• Time - A fair amount of it, especially if this is our first rodeo. Especially if the vessel's shape is complex. Especially if the loft itself must be built.

I can't count the number of times I've bemoaned this list, only to have someone tell me how simple and easy it all is. Only problem is that I've done it and it isn't.

Let's see what can be done to ease our way...

Simple Vessels in Sheet Materials

The first step is to simplify the problem.

Sheet materials generally lie flat or follow a section-of-cylinder or section-of-cone. Vessels built from them are a subset of shapes which - as a class - are generally much easier to loft and build.

NOTE: Sheet materials may also be tortured into compound curves but that ain't entirely simple, neither!

Simple vessels with fewer and simpler curves are easier to loft and build. In this post and lead image, I attempt a rough hierarchy of vessel shape complexity.

Lofting Space

Clearly, if we can take the loft out of lofting, we're ahead of the game.

Phil Bolger with Dynamite Payson popularized Instant Boats in their book(s) of the same name. A key feature is that the lines are laid down (lofted) directly on flat panels (e.g., bottoms, sides, decks and components) before bending into shape. Such lines are said to be expanded.

Following this practice, one eliminates the separate lofting floor. Time and potential errors are saved as most lines are directly cut to shape the panels (no transfer from loft to materials).

In our (flat and rockered bottom) builds, we've taken to building the bottom first, in sections which are finished, flipped and joined. While still flat, we use this structure as a building platform for bulkheads, sides and other components. Once ready, we assemble the structure building upwards from the bottom. This saves flipping a vessel that has been built inverted.

Esoteric Skills

By this point, the 3D shape of the vessel has been chosen and designed for low complexity. Required skills are accordingly much reduced. 

Spatial visualization is far less taxed. Cross-references are minimal and straight-forward. Curves are simple and simply faired. Corrections are mostly limited to point control (vs the correction and coordination of interrelated lines).

Design can go a long way toward easing or eliminating spiling. Box-Barge/Scows, for example are self-rectifying (if the edges meet, they pull themselves into square). Their parallel sides and dead-flat bottom sections mean 'house-carpentry' for most of the hull (no spiling at all!).

In TriloBoats, the use of whole and simple fractions of sheets mean laying out and cutting are held to the minimum, with attendant reductions in waste.

Special Tools

While a few special tools will likely be necessary in any hull shape more complex than the simple box, simplifying holds them to a handful.

In particular, simple curves allow stiffer splines that are generally three point curves (two control points - one toward each end - plus one somewhere in the middle. Unlike the more sophisticated tools for fairing complex curves, simple weights over a sharp corner suffice (of a plank, say, or paperback book).

Design can often help here, too - employing simple rectangles and arcs of a circle - to eliminate splines and rolling bevels.

Time

Everything discussed here has saved time. Time, time, time, time.

Lofting space comes 'free' with the vessel being built. This is (infra)structure right at hand (no round-trip to the loft, looking for a clue).

Simpler lines are laid down once with straight edge, simple spline and radius, and rarely 'taken up'. Cuts are made directly along these lines. Spiling is reduced.

At the extreme end (box-barge/scows) much time is saved in layout, cutting and squaring up the hull. Spiling, most bevels and all rolling bevels are reduced or eliminated.

Bolger never liked the term instant boat, but we can sure edge closer!

*****

Nothing I've written here is in disparagement of lofting or the complex end of vessel space. I love those Curvy Dogs! I respect those who lavish their skill, time, energy and passion in every aspect of their construction.

But like I said, I'm lazy. What's more...

I'd rather be sailing!