update-2/10/2017- added a half hull model file suitable for printing or CNC

I was cruising around on Thingiverse and noticed the STEAM challenges, particularly #makeitfloat. After just a few minutes reading about the contest, I knew exactly what I was going to design and print and how to integrate the STEAM requirements!

I love the romance of wooden sailboats. They are a wonderful marriage of art and science. Each one crafted by a maker's hands, its design influenced by the scientific interaction of wind, wood, and water. It's so cool that a mathematically and aesthetically beautiful shape are the same thing!

There is a small sailboat I have always wanted to build for myself. The Herreshoff 12 1/2-footer, designed by "The Wizard of Bristol" N.G Herreshoff and first built in 1914. Over time, this boat has assumed archetype status in the field of small wooden sailboat designs. It inspired Joel White, a modern naval designer, to develop a version with a retractable centerboard, the Haven 12 1/2. Mr. White's willingness to combine historic and modern design inspired a new generation of 12 1/2 makers to build them using modern techniques and materials, while staying true to Herreshoff's charming daysailer lines. Thanks to inspiration from the #makeitfloat challenge, I decided to put a Maker's twist on history using modern desktop 3D design and printing methods.

Working from found images only, I began reconstructing the Mini-me version of the Haven in my 3d design software. Not surprisingly, I had to revise parts and design details to accommodate the size, printability, and purpose for which my design was intended, a sort-a-scale model, not a sailboat for 4 adults. Once the virtual model was complete, I added in the Makerbot logo as a finishing touch, swapped the fraction for a decimal, and christened this vessel, Maker 12.5 in tribute to its heritage. A bit of old, a splash of new, and a sprinkle of Makerdust!

In addition, there is a nautical science aspect using coinage that can be demonstrated with this model using the 12 1/2 foot load waterline length (LWL) measurement that gives the craft half its name. I have split this model at the LWL to make the line obvious and for ease of printing. With that in mind.... PREPARE FOR SCIENCE!

The waterline is often indicated by a stripe or color change down the broad side of the hull. It serves as a visual reference to the trim of the boat in the water. A naval architect computes the weight of the boat and its gear, passengers, and cargo and integrates that information into the hull design to generate the LWL line. Although a waterline can be any line where the hull intersects the water, the LWL is a special line that indicates where the boat will float before it starts to use up its reserve buoyancy. It can also show if the boat has its weight distributed properly fore (to the front) and aft (to the rear) as well as port (left facing forward) and starboard (right facing forward).

As the boat sinks in, the hull displaces the water according to the volume of its hull below the waterline. The term displacement, in this instance, refers to the weight of the water shoved out of the way by the hull. By changing the amount and distribution of the weight around the inside of the boat, we can compare the waterline at sea level with the LWL line on the hull to help make decisions about how the boat is loaded.

Now that you know some nautical history and science, your challenge is to print this little boaty beauty and find the answer to this question: How many quarters does it take to ballast this design at the LWL as designed by the naval architect?

I theorized that it would not take much weight, but I was concerned that it might not float at all! Nonetheless, I started filling the sink for testing. I did have some small hurdles to deal with that did not become evident until testing. The main issue was knowing that due to the sparse infill, this design was not watertight and would gradually flood with water, affecting the test. I solved that issue by applying a thin layer of plastic wrap over the hull. The second was that the model was biased toward one side due to the angle of the sail rig, so I had to compensate by offsetting the ballast to the side. Once those problems were worked out, I started loading quarters and arranging them to find the answer to my question for the #makeitfloat challenge.

So, how did it turn out? Check the pictures above for the results. I had already tinted the hull, so I used a thin layer of plastic wrap on it to keep the color from bleeding while it was in the water. The first test result pic shows the Maker 12.5 with the quarters in place and the second shows the results at the waterline when ballasted.

More info is on the instructions page. I also wrote an article for 3dprint.com about the process, giving Thingiverse a shout out. http://3dprint.com/81733/3d-printed-dailboat/