Building a Cardboard Boat

Well, I haven't lost my mind. I've actually come to my senses. The idea is to design a boat in corrugated cardboard.  It couldn't be simpler. Boat designers spend a lot of time of time planning how to build a boat. They draft or they make models, both very time consuming. I know, I've been there.

Boat design, even for the smallest craft, is actually quite complicated. One of the problems deals with a drafting term called "true view." A boat hull is generally made from plywood which is bent or curved. This creates a twofold challenge: first, how to draw a curvalinear three dimensional object on flat paper. The second problem is how to determine what all of those curved components look like when they laid out on flat plywood in the shop.

Granted, there is computer software that does all this, but it is not cheap. On the other hand, one can make a scale model, but sometimes it is difficult to work these components up to full scale. A quarter inch can mean a lot when putting together plywood, but numbers that small are not always seen in the scale model.

The cardboard model is, of course, exactly the same size as the intended boat: no need for special software, no need to scale up from small to large. Along the way, I learned a lot about drafting out a boat (called lofting in the nautical business), bending and unbending, and fitting everything together as well. It only took a few hours to do. Along the way, I made a lot of small changes that will greatly improve the performance of this boat.

I begin by drafting the two bilge panels and cutting them  out.  The curves are drawn with  a spline  made from  half  inch mahogany

I tape them together along the center  line which has been cut  along a  gentle curve.

Then the panels are unfolded. Note that the stem is raised about 7 inches above the  work  table.  This  is a desirable hull feature in hull design called the rocker.  I know from experience that seven inches will keep the stem above the waves.

Next I add a stem, stern, and side strakes. The strakes are about  10 1/2 inches high.  Experience tells me this is about right. Too high and they catch the wind ( windage) too low and the boat could be swamped in rough water.  A temporary cardboard bulkhead is places in the center to support the hull shape.

The model still has a way to go. You may notice that I wrote out a couple notes on some of the components. I intend to do more cutting and trimming. 

When finished, this will be the dinghy that my summer class will build. I will transfer the work onto luan templates which they can copy.  See you then!