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/

Instructions

So, are you ready to think about printing and putting one together? YAY!

First, I want to let you know that this is not a simple print and it is not going to just pop together like building blocks. You will need some patience and willingness to pay attention to fit and detail. Your printer will need to be in a very good state of tune for this one as well. Even then, you will need to do some fine filing and sanding. Don't worry, if you built models or Legos, it won't be too bad. You should only need light cleanup passes, not aggressive removal. Also, be prepared to look up some nautical terms to help you identify the parts.

I designed this for a filament printer with a 250 x 200 mm bed that can print between .15 and .25 mm thick layers. If you take a close look at the sail rig STL files, you will see tiny details that are likely to be too small for your filament printer to fully resolve. I knew these details would not make it through the slicer at these slice thicknesses, but I did know there would be enough to give a helping hand for assembly. You will find handy bevels for aligning and pockets for holding things in place well enough for you to apply some tape and get the superglue on them. Due to the nature of this design, it will probably not print well at a smaller scale when using a filament printer, but you could make it bigger!

Speaking of the STL files, there are a lot of them, but they are organized as single items and groups. For instance, you can print all the stand parts at once or just a leg. You can print all the "wooden" sail rigging or just one part. There are split mainsail files for most printers and a full mainsail file for a very large printer. There is even a full "assembled" STL model to help you figure out where things go and how, but do NOT use the full model to attempt a complete print, the parts are not properly oriented for printing or connected to each other! Other than the complete model file, the other STL files should drop onto your build plate pre-oriented for filament printing.

Here is a list of the parts and print settings I used (layer height, fill, shells):

•Hull top: .25mm, 30% fill, 2 shells with supports enabled. - This print will want to lift a bit, so make sure it is well attached to the print bed. The mount hole for the jib club should be reamed as needed. The mast step hole should be trimmed to fit the mast if needed.

•Hull bottom: .25mm, 30%, 3 shells -This definitely will try to lift at the edges, even pulling up tape, so watch for it.

•Centerboard: .15mm, 30%, 2 shells -May need light filing to fit the pockets in the hull bottom

•Boom, tiller, mast, gaff, jib club: .15mm, 50%, 2 shells -Look out for print flanging at layer one. These parts have angled pockets to hold the sails. The jib club mount will need some rounding with a file to fit its hole.

•Stand(all): .25mm, 30%, 2 shells -May need light filing to fit parts together.

•Sails(all): .15mm, 100%, 3 shells with a single layer raft and supports enabled - Most of this print involves support rather than sail, so I used a raft to guarantee the supports would adhere. The sail edges should all have a slight bevel on the edges to help them fit, but you will probably have to file them a bit more. Make sure you have supports set for easy removal, but even if you do, you may have to struggle a bit to remove them near the flat corners. It helps to place the sail side down on your workbench and pry away the supports with a putty knife. The support side of the sail is probably going to need a light sanding to remove nibs. It is bit of work, but it will be worth it! (note: Wish I had a dual extruder for printing dissolvable supports!)

Options (as in photos):

•All parts printed in natural color (warm tone) translucent PLA. I took advantage of how the lines of the boat, translucent filament, slicing and printed texture could interact and enhance the forms, especially when lit from behind.

•Red Sharpie wide chisel-tip marker for M logo and lower hull. I did one iteration of the lower hull in solid red filament, which was nice, but the red over translucent is gorgeous.

•BR103 Potato Brown Shinhanart Touch chisel-tip marker for "wooden" parts. Again, the part layout takes advantage of the printing process, giving a sense of wood grain when tinted.

Supplies: Hobby knife, superglue and accelerator, 220ish grit sandpaper, a 6" fine tooth flat file, blue painter's tape

YMMV for all of these depending on your hardware, software, supplies on hand, and personal 3D printing experience.

Printing and assembly:

1. Start with the smallest parts and work your way up. Depending on your settings, some of these parts can take a while to print, up to several hours for the large parts. The interlocking parts have .20mm clearances designed in to help assembly, so test fit before filing too much.

Trim, test fit, and color all parts before final assembly. Use multiple, light applications of marker to prevent color bleeding.2. Start assembly with the jib. Insert the jib club into the nose of the hull so it is a friction fit and orient it as in the model. Slip the jib into the groove on the jib club. Use tape to secure the sail to the jib club and use a piece to help orient it towards the mast. Then apply a few drops of superglue to tack it in place. Remove the tape and apply more glue. Ideally, the jib assembly will be self supporting and removable.3. Now that you have done the jib, you will use a similar technique on the mainsail. It will be a nine-handed job, but you should be able to tape it up using the helper grooves and start tacking it together. Go slow, be patient, it can be done! After the mainsail assembly is complete, the rest will be a piece of cake. You should not need to glue the mainsail assembly to the hull, allowing it to be removed if needed.4. Attach the hull halves together, making sure your edges are aligned. Make sure your mating edges are not flanged. Once united, it should produce a smooth hull surface.5. Glue in the tiller and centerboard, making sure to keep them oriented correctly.6. Assemble the stand with no glue, using tape as needed. Then, place the completed boat on the stand temporarily to make sure all the parts are aligned and tack glue the stand together. Remove the boat and finish gluing the stand. You are all done!7. Try the #makeitfloat challenge if you like. By removing or changing the angle of sail assemblies, you can influence the amount and placement of the ballast.

PS- When you place this model on a flat surface without the bottom half of the hull and stand attached, it looks as if it was floating in the water. It is very cool looking and I am going to be making more of this iteration to give as gifts!